gjb2048/FreeSpace.java

## FreeSpace.java
/*
 * FreeSpace JNI class.
 * © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
 *
 * Defines the native functions to use and loads the resulting 'libfreespace.so' for Java to use at runtime.
 *
 * Start here.
 * So with this file operating above the package folder:
 * javac miniwebserver/FreeSpace.java to generate the .class file for FreeSpaceMiniWebServer.
 * javah miniwebserver.FreeSpace to generate the miniwebserver_FreeSpace.h file with the function declarations to implement.
 * Then look at the instructions in miniwebserver_FreeSpace.c.
 *
 * Useful websites:
 * http://jonisalonen.com/2012/calling-c-from-java-is-easy/
 * http://www.steveolyo.com/JNI/JNI.html
 */
package miniwebserver;

/**
 * @author G J Barnard
 */
public class FreeSpace
{
    // Load the C dynamic 'so' library which will contain the implemented 'C' functions....
    static
    {
        System.loadLibrary("freespace");
    }

    // C functions - can be implemented in C++....
    public static native String getFreeSpace(String device);
}

## FreeSpaceMiniWebServer.java
/*
 * Free Space Mini web server.
 * © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
 */
package miniwebserver;

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.NetworkInterface;
import java.net.URI;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Date;
import java.util.Enumeration;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.zip.GZIPOutputStream;

/**
 * @author G J Barnard
 */
public class FreeSpaceMiniWebServer implements HttpHandler
{
    private MimeTypeFactory mimeTypeFactory = new MimeTypeFactory();
    public static final int BUFFER_MAX = 65536 - 40;  // Max packet size less TCP/IP headers etc.  Use WireShark (http://www.wireshark.org/) to see what I mean.
    private static String userdir = System.getProperty("user.dir");
    private static String MWS_TITLE = "FreeSpaceMiniWebServer";

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        Thread.setDefaultUncaughtExceptionHandler(new FreeSpaceMiniWebServer.freeSpaceMiniWebServerExceptionHandler());
        FreeSpaceMiniWebServer us = new FreeSpaceMiniWebServer();
    }

    /**
     * Constructor
     */
    public FreeSpaceMiniWebServer()
    {
        System.out.println("Free Space Mini Web Server");
        System.out.println("User directory is: " + userdir);
        createServer();
    }

    /**
     * Destructor.
     * @param exitCode The exit code.
     */
    public static void destruct(int exitCode)
    {
        System.exit(exitCode);
    }

    /**
     * Should execute in response to a Ctrl-C etc.
     */
    protected static class freeSpaceMiniWebServerExceptionHandler implements Thread.UncaughtExceptionHandler
    {
        @Override
        public void uncaughtException(Thread t,
                Throwable e)
        {
            System.out.println("Free Space Mini Web Server Java VM Exception: " + e.getMessage() + " from " + t.getName());
            System.out.println("Need to quit!");

            destruct(-1);
        }
    }

    /**
     * Create the web server on the given port serving the specified context.
     */
    private void createServer()
    {
        int httpPort = 8084;
        InetSocketAddress address = new InetSocketAddress(httpPort);
        try
        {
            HttpServer theServer = HttpServer.create(address, 0);

            theServer.createContext("/", this);
            createThreads(theServer);  // Try without to see the difference of not having multiple threads to serve the requests.
            theServer.start();

            String hostname = InetAddress.getLocalHost().getHostName();
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            if (interfaces != null)
            {
                while (interfaces.hasMoreElements())
                {
                    NetworkInterface ni = interfaces.nextElement();
                    Enumeration<InetAddress> interfaceAddresses = ni.getInetAddresses();
                    while (interfaceAddresses.hasMoreElements())
                    {
                        InetAddress interfaceAddress = interfaceAddresses.nextElement();
                        System.out.println("Accepting requests on " + hostname + ", interface " + ni.getDisplayName() + " - " + interfaceAddress.getHostAddress() + ":" + httpPort);
                    }
                }
            }
            else
            {
                System.out.println("Free Space Mini Web Server - No known network interfaces.");
            }
        }
        catch (IOException e)
        {
            e.printStackTrace(System.err);
        }
    }

    /**
     * Setup the thread and queue creation classes.
     *
     * @param theServer The server that will receive with the requests.
     */
    private void createThreads(HttpServer theServer)
    {
        int corePoolSize = 20;
        int maximumPoolSize = 40;
        long keepAliveTime = 10;
        TimeUnit unit = TimeUnit.SECONDS;
        int workQueueCapacity = 40;
        int threadPriority = Thread.NORM_PRIORITY;

        System.out.println(MWS_TITLE + ":createThreads - Creating thread factory with a thread priority of: " + threadPriority);
        MiniWebServerThreadFactory threadFactory = new MiniWebServerThreadFactory(threadPriority);

        System.out.println(MWS_TITLE + ":createThreads - Creating thread pool executor with:");
        System.out.println("Core Pool Size     : " + corePoolSize);
        System.out.println("Maximum Pool Size  : " + maximumPoolSize);
        System.out.println("Keep Alive Time    : " + keepAliveTime + " seconds.");
        System.out.println("Work Queue Capacity: " + workQueueCapacity);

        MiniWebServerThreadPoolExecutor threadExecutor =
                new MiniWebServerThreadPoolExecutor(
                corePoolSize,
                maximumPoolSize,
                keepAliveTime,
                unit,
                workQueueCapacity,
                threadFactory);

        theServer.setExecutor(threadExecutor);
    }

    /**
     * Handle the HTTP request.
     *
     * @param request Request to process.
     * @throws IOException If error.
     */
    @Override
    public void handle(HttpExchange request) throws IOException
    {
        long handleTimeNS = System.nanoTime();
        long handleTimeMS = System.currentTimeMillis();
        processRequest(request);
        handleTimeNS = System.nanoTime() - handleTimeNS;
        handleTimeMS = System.currentTimeMillis() - handleTimeMS;
        System.out.println(request.getRequestURI().toString() + " took " + handleTimeNS + "ns or " + handleTimeMS + "ms.");
    }

    /**
     * Process the HTTP request.
     * @param request The request.
     */
    private void processRequest(HttpExchange request)
    {
        // TODO: Process specific URL's, GET and POST requests.

        URI dUrl = request.getRequestURI();
        String rawPath = dUrl.getRawPath();

        if (rawPath.length() > 1)
        {
            sendFile(request, rawPath);
        }
        else if (rawPath.charAt(0) == '/')
        {
            sendIndex(request);
        }
        else
        {
            // Bogus request...
            Headers responseHeaders = request.getResponseHeaders();
            responseHeaders.set("Date", new Date().toString());
            responseHeaders.set("Server", MWS_TITLE);

            try
            {
                request.sendResponseHeaders(HttpURLConnection.HTTP_BAD_REQUEST, 0);
            }
            catch (IOException ex)
            {
                System.err.println(MWS_TITLE + ":processRequest - Bad request.");
                ex.printStackTrace(System.err);
            }
            request.close();
        }
    }

    /**
     * Send the 'index' file which is actually just the context of '/'.
     * @param request
     */
    private void sendIndex(HttpExchange request)
    {
        System.out.println(MWS_TITLE + ":sendIndex - " + request.getRequestURI().toString());

        Headers responseHeaders = request.getResponseHeaders();

        responseHeaders.set("Content-type", mimeTypeFactory.HTML.getType());
        responseHeaders.set("Date", new Date().toString());
        responseHeaders.set("Server", MWS_TITLE);

        try
        {
            String contents = "<html><head><link rel=\"stylesheet\" type=\"text/css\" href=\"fsmws.css\"><title>Free Space Mini Web Server</title></head><body><h1>" + FreeSpace.getFreeSpace("/") + "</h1></body></html>";
            request.sendResponseHeaders(HttpURLConnection.HTTP_OK, contents.length());
            try (OutputStream os = request.getResponseBody())
            {
                os.write(contents.getBytes());
                os.flush();
            }
            request.close();
        }
        catch (Exception e)
        {
            e.printStackTrace(System.err);
        }
    }

    /**
     * Send the given file to the web browser with the correct MIME type. Looks in the users directory for the file.
     *
     * @param request The request this is for.
     * @param file The file to send.
     */
    private void sendFile(HttpExchange request, String file)
    {
        String fullname = userdir + file;
        System.out.println(MWS_TITLE + ":sendFile - " + request.getRequestURI().toString() + " - " + fullname);

        File theFile = new File(fullname);

        if (theFile.exists())
        {
            MimeType theType = mimeTypeFactory.guessContentTypeFromName(file);

            byte[] fileContents = getFile(theFile);
            if (fileContents != null)
            {
                Headers responseHeaders = request.getResponseHeaders();
                responseHeaders.set("Date", new Date().toString());
                responseHeaders.set("Server", MWS_TITLE);

                responseHeaders.set("Content-type", theType.getType());
                if (theType.isBinary())
                {
                    try
                    {
                        // Info on http://elliotth.blogspot.com/2009/03/using-comsunnethttpserver.html
                        responseHeaders.set("Content-Encoding", "gzip");
                        request.sendResponseHeaders(HttpURLConnection.HTTP_OK, 0);  // Don't know how large the compressed file will be.
                        try (GZIPOutputStream gos = new GZIPOutputStream(request.getResponseBody(), BUFFER_MAX))
                        {
                            gos.write(fileContents);
                            gos.finish();
                        }
                        catch (Exception ex)
                        {
                            System.err.println(MWS_TITLE + ":sendFile - Binary file: " + file);
                            ex.printStackTrace(System.err);
                        }
                    }
                    catch (IOException ex)
                    {
                        System.err.println(MWS_TITLE + ":sendFile - Binary file: " + file);
                        ex.printStackTrace(System.err);
                    }
                }
                else
                {
                    try
                    {
                        request.sendResponseHeaders(HttpURLConnection.HTTP_OK, fileContents.length);
                        try (OutputStream os = request.getResponseBody())
                        {
                            os.write(fileContents);
                            os.flush();
                        }
                        catch (Exception ex)
                        {
                            System.err.println(MWS_TITLE + ":sendFile - Text file: " + file);
                            ex.printStackTrace(System.err);
                        }
                    }
                    catch (IOException ex)
                    {
                        System.err.println(MWS_TITLE + ":sendFile - Text file: " + file);
                        ex.printStackTrace(System.err);
                    }
                }

                request.close();
            }
            else
            {
                // File has no content...
                try
                {
                    // File does not exist.
                    request.sendResponseHeaders(HttpURLConnection.HTTP_NO_CONTENT, 0);
                    request.close();
                }
                catch (IOException ex)
                {
                    System.err.println(MWS_TITLE + ":sendFile - Sending response headers for file: " + file);
                    ex.printStackTrace(System.err);
                }

                System.err.println(MWS_TITLE + ":sendFile - File '" + file + "' has no content.");
            }
        }
        else
        {
            // Code above has not got the file...
            try
            {
                // File does not exist.
                request.sendResponseHeaders(HttpURLConnection.HTTP_NOT_FOUND, 0);
                request.close();
            }
            catch (IOException ex)
            {
                System.err.println(MWS_TITLE + ":sendFile - Sending response headers for file: " + file);
                ex.printStackTrace(System.err);
            }

            System.err.println(MWS_TITLE + ":sendFile - File '" + file + "' not sent.");
        }
    }

    /**
     * Gets the given file from the operating system.
     *
     * @param theFile The file to get.
     * @return The file as a byte array.
     */
    private byte[] getFile(File theFile)
    {
        byte[] buffer = null;

        FileInputStream fis = null;
        try
        {
            fis = new FileInputStream(theFile);
            FileChannel fc = fis.getChannel();
            long len = theFile.length();
            int byteReadCount = 0;
            ByteBuffer byteBuffer = ByteBuffer.allocate((int) len);

            int bytesRead = 0;
            while ((bytesRead != -1) && (byteReadCount < len))
            {
                bytesRead = fc.read(byteBuffer);
                byteReadCount += bytesRead; // Cope with 0 return when have reached end of text file and cannot get -1 byte as buffer is full.
            }
            buffer = byteBuffer.array();
        }
        catch (FileNotFoundException ex)
        {
            ex.printStackTrace(System.err);
        }
        catch (IOException ex)
        {
            ex.printStackTrace(System.err);
        }
        catch (Exception ex)
        {
            ex.printStackTrace(System.err);
        }
        finally
        {
            if (fis != null)
            {
                try
                {
                    fis.close();
                }
                catch (IOException ex)
                {
                    ex.printStackTrace(System.err);
                }
            }
        }

        return buffer;
    }

    /**
     * Factory to create the threads to serve the requests.
     */
    private class MiniWebServerThreadFactory implements ThreadFactory
    {
        private ThreadGroup miniWebServerThreadGroup = new ThreadGroup("Free Space Mini Web Server Thread Group");
        private int threadPriority = Thread.NORM_PRIORITY;
        private int threadCount = 0;

        /**
         * Constructor
         *
         * @param threadPriority The priority all threads are created with.
         */
        public MiniWebServerThreadFactory(int threadPriority)
        {
            this.threadPriority = threadPriority;
        }

        /**
         * Creates a new thread.
         *
         * @param r The runnable task the thread is created for.
         * @return A new thread.
         */
        @Override
        public Thread newThread(Runnable r)
        {
            Thread theThread = new Thread(miniWebServerThreadGroup, r, "FSMWS HTTP Server Thread-" + ++threadCount);

            theThread.setPriority(threadPriority);

            return theThread;
        }

        /**
         * Gets the thread group that all leader board threads belong to.
         *
         * @return The thread group.
         */
        public ThreadGroup getLeaderBoardThreadGroup()
        {
            return miniWebServerThreadGroup;
        }

        /**
         * Gets all the current threads.
         *
         * @return The threads.
         */
        public Thread[] getThreads()
        {
            Thread[] theThreads = new Thread[miniWebServerThreadGroup.activeCount()];

            int threads = miniWebServerThreadGroup.enumerate(theThreads);

            System.out.println(MWS_TITLE + "ThreadFactory:getThreads - " + threads + " active threads returned.");

            return theThreads;
        }

        /**
         * Sets the thread priority for all new threads.
         *
         * @param threadPriority The thread priority.
         */
        public void setThreadPriority(int threadPriority)
        {
            // TODO: Set thread priority of all existing threads too.
            this.threadPriority = threadPriority;
        }
    }

    /**
     * Executor to manage what thread will serve an incoming request.
     */
    private class MiniWebServerThreadPoolExecutor extends ThreadPoolExecutor
    {
        /**
         * See http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.html#ThreadPoolExecutor(int,
         * int, long, java.util.concurrent.TimeUnit, java.util.concurrent.BlockingQueue, java.util.concurrent.ThreadFactory)
         *
         * @param corePoolSize
         * @param maximumPoolSize
         * @param keepAliveTime
         * @param unit
         * @param workQueueCapacity
         * @param threadFactory
         */
        public MiniWebServerThreadPoolExecutor(
                int corePoolSize,
                int maximumPoolSize,
                long keepAliveTime,
                TimeUnit unit,
                int workQueueCapacity,
                ThreadFactory threadFactory)
        {
            super(corePoolSize,
                    maximumPoolSize,
                    keepAliveTime,
                    unit,
                    new MiniWebServerBlockingQueue<Runnable>(workQueueCapacity),
                    threadFactory);
        }
    }

    @SuppressWarnings("hiding")
    private class MiniWebServerBlockingQueue<Runnable>
            extends LinkedBlockingQueue<Runnable>
    {
        private static final long serialVersionUID = -3943671634425379250L;

        /**
         * Constructor
         *
         * @param capacity Capacity of the queue.
         */
        public MiniWebServerBlockingQueue(int capacity)
        {
            super(capacity);
        }
    }

    /**
     * Class to store and determine MIME types - RFC2616 Section 19.4.
     */
    private class MimeType
    {
        private boolean isBinary;
        private String type;
        public static final String HTML_STR = "text/html";
        public static final String JSON_STR = "application/json";
        public static final String TEXT_STR = "text/plain";

        /**
         * Constructor
         *
         * @param isBinary States if we are a binary type.
         * @param type The type we are.
         */
        public MimeType(boolean isBinary, String type)
        {
            this.isBinary = isBinary;
            this.type = type;
        }

        /**
         * States if we are a binary type.
         *
         * @return true or false.
         */
        public boolean isBinary()
        {
            return isBinary;
        }

        /**
         * States the MIME type.
         *
         * @return The type.
         */
        public String getType()
        {
            return type;
        }
    }

    /**
     * Factory to create MimeType's.
     */
    private class MimeTypeFactory
    {
        public MimeType HTML = new MimeType(false, MimeType.HTML_STR);
        public MimeType JSON = new MimeType(false, MimeType.JSON_STR);
        public MimeType TEXT = new MimeType(false, MimeType.TEXT_STR);

        /**
         * Try to guess the content type from the filename.
         *
         * @param name Name of the file to guess.
         * @return Guessed MIME type text.
         */
        public MimeType guessContentTypeFromName(String name)
        {
            if (name.endsWith(".html") || name.endsWith(".htm"))
            {
                return new MimeType(false, MimeType.HTML_STR);
            }
            else if (name.endsWith(".txt") || name.endsWith(".java"))
            {
                return new MimeType(false, "text/plain");
            }
            else if (name.endsWith(".gif"))
            {
                return new MimeType(true, "image/gif");
            }
            else if (name.endsWith(".class"))
            {
                return new MimeType(true, "application/octet-stream");
            }
            else if (name.endsWith(".jpg") || name.endsWith(".jpeg"))
            {
                return new MimeType(true, "image/jpeg");
            }
            else if (name.endsWith(".js"))
            {
                return new MimeType(false, "text/javascript; charset=UTF-8");
            }
            else if (name.endsWith(".css"))
            {
                return new MimeType(false, "text/css");
            }
            else if (name.endsWith(".png"))
            {
                return new MimeType(true, "image/png");
            }
            else if (name.endsWith(".otf"))
            {
                //return new MimeType(true, "vnd.oasis.opendocument.formula-template"); // http://www.iana.org/assignments/media-types/application/vnd.oasis.opendocument.formula-template
                return new MimeType(true, "font/opentype");  // Chrome 'no winge' with this.
            }
            else if (name.endsWith(".ico"))
            {
                return new MimeType(true, "image/vnd.microsoft.icon");
            }
            else if (name.endsWith(".swf"))
            {
                return new MimeType(true, "application/x-shockwave-flash");
            }
            else
            {
                return new MimeType(false, MimeType.HTML_STR);
            }
        }
    }
}

## fsmws.css
/*
 * FreeSpace JNI C implementation.
 * © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
 */
@charset "UTF-8";

body {
    font-family: sans-serif;
    background-color: lightgoldenrodyellow;
    text-align: center;
}

## miniwebserver_FreeSpace.c
/*
 * FreeSpace JNI C implementation.
 * © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
 *
 * When running standalone, pass in filepath, i.e. '/'.
 *
 * Using Java7 on user account 'demo' with a sub folder of 'Java' so adjust the following as required.
 * Include the JNI headers etc.: export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-armhf
 * Compile to object file: gcc -fPIC -c miniwebserver_FreeSpace.c -I $JAVA_HOME/include
 * Compile to library: gcc miniwebserver_FreeSpace.o -shared -o libfreespace.so -Wl,-soname,freespace
 * Compile the Java class that uses FreeSpace which loads libfreespace.so: javac miniwebserver/FreeSpaceMiniWebServer.java
 * Tell the system where to find the libfreespace.so dynamic library: export LD_LIBRARY_PATH=/home/demo/Java
 * Run the program: java miniwebserver/FreeSpaceMiniWebServer
 */

#include "miniwebserver_FreeSpace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/vfs.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <stdlib.h>

int calcfreespace(const char *device);
char* displaydetails();
char* displayfreespace();
int exitcode;
char result[1024];
char hostname[128];
struct stat sbuf;
struct statfs buf;
char* thedevice;
extern char* ctime();

main(argc, argv)
int argc;
char **argv;
{
    if (argc != 2) {
        fprintf(stderr, "usage: us filesys-name\n");
        exitcode = 1;
    }
    else if (calcfreespace(argv[1]) == 0)
    {
        printf(displaydetails());
        printf("\n");
        printf(displayfreespace());
        printf("\n");
    }
    else
    {
        printf(result);
        printf("\n");
    }

    exit(exitcode);
}

int calcfreespace(const char *device)
{
    if (stat(device, &sbuf) < 0) {
        sprintf(result, "stat error");
        exitcode = 2;
    } else {
        if (statfs(device, &buf) < 0) {
            sprintf(result, "statfs error, errno is: %d", errno);
            exitcode = 2;
        } else {
            hostname[127] = '\0';
            gethostname(&hostname, 127);

            exitcode = 0;
            thedevice = device;
        }
    }

    return exitcode;
}

char* displaydetails()
{
    if (exitcode == 0)
    {
        sprintf(result, "%s:\tblocks %u\tfree blocks %u\tblock size %u\tavailable space %u\tfree inodes %u", thedevice, buf.f_blocks, buf.f_bfree, sbuf.st_blksize, buf.f_bavail, buf.f_ffree);
    }

    return result;
}

char* displayfreespace()
{
    unsigned long freebytes;

    if (exitcode == 0)
    {
        long timevalue;
        time(&timevalue);

        freebytes = buf.f_bavail * sbuf.st_blksize;
        sprintf(result, "Available space on %s %lu bytes %luK %fMB %fGB at %s on %s", thedevice, freebytes, (freebytes) / 1024, ((freebytes) / 1024.0) / 1024.0, (((freebytes) / 1024.0) / 1024.0) / 1024.0, ctime(&timevalue), hostname);
    }

    return result;
}

JNIEXPORT jstring JNICALL Java_miniwebserver_FreeSpace_getFreeSpace
  (JNIEnv *env, jclass cls, jstring device)
{
    if (calcfreespace((*env)->GetStringUTFChars(env, device, 0)) == 0)
    {
        return (*env)->NewStringUTF(env, displayfreespace());
    }
    else
    {
        return (*env)->NewStringUTF(env, result);
    }
}
	/*
	* FreeSpace JNI class.
	* © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
	*
	* Defines the native functions to use and loads the resulting 'libfreespace.so' for Java to use at runtime.
	*
	* Start here.
	* So with this file operating above the package folder:
	* javac miniwebserver/FreeSpace.java to generate the .class file for FreeSpaceMiniWebServer.
	* javah miniwebserver.FreeSpace to generate the miniwebserver_FreeSpace.h file with the function declarations to implement.
	* Then look at the instructions in miniwebserver_FreeSpace.c.
	*
	* Useful websites:
	* http://jonisalonen.com/2012/calling-c-from-java-is-easy/
	* http://www.steveolyo.com/JNI/JNI.html
	*/
	package miniwebserver;

	/**
	* @author G J Barnard
	*/
	public class FreeSpace
	{
	// Load the C dynamic 'so' library which will contain the implemented 'C' functions....
	static
	{
	System.loadLibrary("freespace");
	}

	// C functions - can be implemented in C++....
	public static native String getFreeSpace(String device);
	}
	/*
	* Free Space Mini web server.
	* © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
	*/
	package miniwebserver;

	import com.sun.net.httpserver.Headers;
	import com.sun.net.httpserver.HttpExchange;
	import com.sun.net.httpserver.HttpHandler;
	import com.sun.net.httpserver.HttpServer;
	import java.io.File;
	import java.io.FileInputStream;
	import java.io.FileNotFoundException;
	import java.io.IOException;
	import java.io.OutputStream;
	import java.net.HttpURLConnection;
	import java.net.InetAddress;
	import java.net.InetSocketAddress;
	import java.net.NetworkInterface;
	import java.net.URI;
	import java.nio.ByteBuffer;
	import java.nio.channels.FileChannel;
	import java.util.Date;
	import java.util.Enumeration;
	import java.util.concurrent.LinkedBlockingQueue;
	import java.util.concurrent.ThreadFactory;
	import java.util.concurrent.ThreadPoolExecutor;
	import java.util.concurrent.TimeUnit;
	import java.util.zip.GZIPOutputStream;

	/**
	* @author G J Barnard
	*/
	public class FreeSpaceMiniWebServer implements HttpHandler
	{
	private MimeTypeFactory mimeTypeFactory = new MimeTypeFactory();
	public static final int BUFFER_MAX = 65536 - 40; // Max packet size less TCP/IP headers etc. Use WireShark (http://www.wireshark.org/) to see what I mean.
	private static String userdir = System.getProperty("user.dir");
	private static String MWS_TITLE = "FreeSpaceMiniWebServer";

	/**
	* @param args the command line arguments
	*/
	public static void main(String[] args)
	{
	Thread.setDefaultUncaughtExceptionHandler(new FreeSpaceMiniWebServer.freeSpaceMiniWebServerExceptionHandler());
	FreeSpaceMiniWebServer us = new FreeSpaceMiniWebServer();
	}

	/**
	* Constructor
	*/
	public FreeSpaceMiniWebServer()
	{
	System.out.println("Free Space Mini Web Server");
	System.out.println("User directory is: " + userdir);
	createServer();
	}

	/**
	* Destructor.
	* @param exitCode The exit code.
	*/
	public static void destruct(int exitCode)
	{
	System.exit(exitCode);
	}

	/**
	* Should execute in response to a Ctrl-C etc.
	*/
	protected static class freeSpaceMiniWebServerExceptionHandler implements Thread.UncaughtExceptionHandler
	{
	@Override
	public void uncaughtException(Thread t,
	Throwable e)
	{
	System.out.println("Free Space Mini Web Server Java VM Exception: " + e.getMessage() + " from " + t.getName());
	System.out.println("Need to quit!");

	destruct(-1);
	}
	}

	/**
	* Create the web server on the given port serving the specified context.
	*/
	private void createServer()
	{
	int httpPort = 8084;
	InetSocketAddress address = new InetSocketAddress(httpPort);
	try
	{
	HttpServer theServer = HttpServer.create(address, 0);

	theServer.createContext("/", this);
	createThreads(theServer); // Try without to see the difference of not having multiple threads to serve the requests.
	theServer.start();

	String hostname = InetAddress.getLocalHost().getHostName();
	Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
	if (interfaces != null)
	{
	while (interfaces.hasMoreElements())
	{
	NetworkInterface ni = interfaces.nextElement();
	Enumeration<InetAddress> interfaceAddresses = ni.getInetAddresses();
	while (interfaceAddresses.hasMoreElements())
	{
	InetAddress interfaceAddress = interfaceAddresses.nextElement();
	System.out.println("Accepting requests on " + hostname + ", interface " + ni.getDisplayName() + " - " + interfaceAddress.getHostAddress() + ":" + httpPort);
	}
	}
	}
	else
	{
	System.out.println("Free Space Mini Web Server - No known network interfaces.");
	}
	}
	catch (IOException e)
	{
	e.printStackTrace(System.err);
	}
	}

	/**
	* Setup the thread and queue creation classes.
	*
	* @param theServer The server that will receive with the requests.
	*/
	private void createThreads(HttpServer theServer)
	{
	int corePoolSize = 20;
	int maximumPoolSize = 40;
	long keepAliveTime = 10;
	TimeUnit unit = TimeUnit.SECONDS;
	int workQueueCapacity = 40;
	int threadPriority = Thread.NORM_PRIORITY;

	System.out.println(MWS_TITLE + ":createThreads - Creating thread factory with a thread priority of: " + threadPriority);
	MiniWebServerThreadFactory threadFactory = new MiniWebServerThreadFactory(threadPriority);

	System.out.println(MWS_TITLE + ":createThreads - Creating thread pool executor with:");
	System.out.println("Core Pool Size : " + corePoolSize);
	System.out.println("Maximum Pool Size : " + maximumPoolSize);
	System.out.println("Keep Alive Time : " + keepAliveTime + " seconds.");
	System.out.println("Work Queue Capacity: " + workQueueCapacity);

	MiniWebServerThreadPoolExecutor threadExecutor =
	new MiniWebServerThreadPoolExecutor(
	corePoolSize,
	maximumPoolSize,
	keepAliveTime,
	unit,
	workQueueCapacity,
	threadFactory);

	theServer.setExecutor(threadExecutor);
	}

	/**
	* Handle the HTTP request.
	*
	* @param request Request to process.
	* @throws IOException If error.
	*/
	@Override
	public void handle(HttpExchange request) throws IOException
	{
	long handleTimeNS = System.nanoTime();
	long handleTimeMS = System.currentTimeMillis();
	processRequest(request);
	handleTimeNS = System.nanoTime() - handleTimeNS;
	handleTimeMS = System.currentTimeMillis() - handleTimeMS;
	System.out.println(request.getRequestURI().toString() + " took " + handleTimeNS + "ns or " + handleTimeMS + "ms.");
	}

	/**
	* Process the HTTP request.
	* @param request The request.
	*/
	private void processRequest(HttpExchange request)
	{
	// TODO: Process specific URL's, GET and POST requests.

	URI dUrl = request.getRequestURI();
	String rawPath = dUrl.getRawPath();

	if (rawPath.length() > 1)
	{
	sendFile(request, rawPath);
	}
	else if (rawPath.charAt(0) == '/')
	{
	sendIndex(request);
	}
	else
	{
	// Bogus request...
	Headers responseHeaders = request.getResponseHeaders();
	responseHeaders.set("Date", new Date().toString());
	responseHeaders.set("Server", MWS_TITLE);

	try
	{
	request.sendResponseHeaders(HttpURLConnection.HTTP_BAD_REQUEST, 0);
	}
	catch (IOException ex)
	{
	System.err.println(MWS_TITLE + ":processRequest - Bad request.");
	ex.printStackTrace(System.err);
	}
	request.close();
	}
	}

	/**
	* Send the 'index' file which is actually just the context of '/'.
	* @param request
	*/
	private void sendIndex(HttpExchange request)
	{
	System.out.println(MWS_TITLE + ":sendIndex - " + request.getRequestURI().toString());

	Headers responseHeaders = request.getResponseHeaders();

	responseHeaders.set("Content-type", mimeTypeFactory.HTML.getType());
	responseHeaders.set("Date", new Date().toString());
	responseHeaders.set("Server", MWS_TITLE);

	try
	{
	String contents = "<html><head><link rel=\"stylesheet\" type=\"text/css\" href=\"fsmws.css\"><title>Free Space Mini Web Server</title></head><body><h1>" + FreeSpace.getFreeSpace("/") + "</h1></body></html>";
	request.sendResponseHeaders(HttpURLConnection.HTTP_OK, contents.length());
	try (OutputStream os = request.getResponseBody())
	{
	os.write(contents.getBytes());
	os.flush();
	}
	request.close();
	}
	catch (Exception e)
	{
	e.printStackTrace(System.err);
	}
	}

	/**
	* Send the given file to the web browser with the correct MIME type. Looks in the users directory for the file.
	*
	* @param request The request this is for.
	* @param file The file to send.
	*/
	private void sendFile(HttpExchange request, String file)
	{
	String fullname = userdir + file;
	System.out.println(MWS_TITLE + ":sendFile - " + request.getRequestURI().toString() + " - " + fullname);

	File theFile = new File(fullname);

	if (theFile.exists())
	{
	MimeType theType = mimeTypeFactory.guessContentTypeFromName(file);

	byte[] fileContents = getFile(theFile);
	if (fileContents != null)
	{
	Headers responseHeaders = request.getResponseHeaders();
	responseHeaders.set("Date", new Date().toString());
	responseHeaders.set("Server", MWS_TITLE);

	responseHeaders.set("Content-type", theType.getType());
	if (theType.isBinary())
	{
	try
	{
	// Info on http://elliotth.blogspot.com/2009/03/using-comsunnethttpserver.html
	responseHeaders.set("Content-Encoding", "gzip");
	request.sendResponseHeaders(HttpURLConnection.HTTP_OK, 0); // Don't know how large the compressed file will be.
	try (GZIPOutputStream gos = new GZIPOutputStream(request.getResponseBody(), BUFFER_MAX))
	{
	gos.write(fileContents);
	gos.finish();
	}
	catch (Exception ex)
	{
	System.err.println(MWS_TITLE + ":sendFile - Binary file: " + file);
	ex.printStackTrace(System.err);
	}
	}
	catch (IOException ex)
	{
	System.err.println(MWS_TITLE + ":sendFile - Binary file: " + file);
	ex.printStackTrace(System.err);
	}
	}
	else
	{
	try
	{
	request.sendResponseHeaders(HttpURLConnection.HTTP_OK, fileContents.length);
	try (OutputStream os = request.getResponseBody())
	{
	os.write(fileContents);
	os.flush();
	}
	catch (Exception ex)
	{
	System.err.println(MWS_TITLE + ":sendFile - Text file: " + file);
	ex.printStackTrace(System.err);
	}
	}
	catch (IOException ex)
	{
	System.err.println(MWS_TITLE + ":sendFile - Text file: " + file);
	ex.printStackTrace(System.err);
	}
	}

	request.close();
	}
	else
	{
	// File has no content...
	try
	{
	// File does not exist.
	request.sendResponseHeaders(HttpURLConnection.HTTP_NO_CONTENT, 0);
	request.close();
	}
	catch (IOException ex)
	{
	System.err.println(MWS_TITLE + ":sendFile - Sending response headers for file: " + file);
	ex.printStackTrace(System.err);
	}

	System.err.println(MWS_TITLE + ":sendFile - File '" + file + "' has no content.");
	}
	}
	else
	{
	// Code above has not got the file...
	try
	{
	// File does not exist.
	request.sendResponseHeaders(HttpURLConnection.HTTP_NOT_FOUND, 0);
	request.close();
	}
	catch (IOException ex)
	{
	System.err.println(MWS_TITLE + ":sendFile - Sending response headers for file: " + file);
	ex.printStackTrace(System.err);
	}

	System.err.println(MWS_TITLE + ":sendFile - File '" + file + "' not sent.");
	}
	}

	/**
	* Gets the given file from the operating system.
	*
	* @param theFile The file to get.
	* @return The file as a byte array.
	*/
	private byte[] getFile(File theFile)
	{
	byte[] buffer = null;

	FileInputStream fis = null;
	try
	{
	fis = new FileInputStream(theFile);
	FileChannel fc = fis.getChannel();
	long len = theFile.length();
	int byteReadCount = 0;
	ByteBuffer byteBuffer = ByteBuffer.allocate((int) len);

	int bytesRead = 0;
	while ((bytesRead != -1) && (byteReadCount < len))
	{
	bytesRead = fc.read(byteBuffer);
	byteReadCount += bytesRead; // Cope with 0 return when have reached end of text file and cannot get -1 byte as buffer is full.
	}
	buffer = byteBuffer.array();
	}
	catch (FileNotFoundException ex)
	{
	ex.printStackTrace(System.err);
	}
	catch (IOException ex)
	{
	ex.printStackTrace(System.err);
	}
	catch (Exception ex)
	{
	ex.printStackTrace(System.err);
	}
	finally
	{
	if (fis != null)
	{
	try
	{
	fis.close();
	}
	catch (IOException ex)
	{
	ex.printStackTrace(System.err);
	}
	}
	}

	return buffer;
	}

	/**
	* Factory to create the threads to serve the requests.
	*/
	private class MiniWebServerThreadFactory implements ThreadFactory
	{
	private ThreadGroup miniWebServerThreadGroup = new ThreadGroup("Free Space Mini Web Server Thread Group");
	private int threadPriority = Thread.NORM_PRIORITY;
	private int threadCount = 0;

	/**
	* Constructor
	*
	* @param threadPriority The priority all threads are created with.
	*/
	public MiniWebServerThreadFactory(int threadPriority)
	{
	this.threadPriority = threadPriority;
	}

	/**
	* Creates a new thread.
	*
	* @param r The runnable task the thread is created for.
	* @return A new thread.
	*/
	@Override
	public Thread newThread(Runnable r)
	{
	Thread theThread = new Thread(miniWebServerThreadGroup, r, "FSMWS HTTP Server Thread-" + ++threadCount);

	theThread.setPriority(threadPriority);

	return theThread;
	}

	/**
	* Gets the thread group that all leader board threads belong to.
	*
	* @return The thread group.
	*/
	public ThreadGroup getLeaderBoardThreadGroup()
	{
	return miniWebServerThreadGroup;
	}

	/**
	* Gets all the current threads.
	*
	* @return The threads.
	*/
	public Thread[] getThreads()
	{
	Thread[] theThreads = new Thread[miniWebServerThreadGroup.activeCount()];

	int threads = miniWebServerThreadGroup.enumerate(theThreads);

	System.out.println(MWS_TITLE + "ThreadFactory:getThreads - " + threads + " active threads returned.");

	return theThreads;
	}

	/**
	* Sets the thread priority for all new threads.
	*
	* @param threadPriority The thread priority.
	*/
	public void setThreadPriority(int threadPriority)
	{
	// TODO: Set thread priority of all existing threads too.
	this.threadPriority = threadPriority;
	}
	}

	/**
	* Executor to manage what thread will serve an incoming request.
	*/
	private class MiniWebServerThreadPoolExecutor extends ThreadPoolExecutor
	{
	/**
	* See http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.html#ThreadPoolExecutor(int,
	* int, long, java.util.concurrent.TimeUnit, java.util.concurrent.BlockingQueue, java.util.concurrent.ThreadFactory)
	*
	* @param corePoolSize
	* @param maximumPoolSize
	* @param keepAliveTime
	* @param unit
	* @param workQueueCapacity
	* @param threadFactory
	*/
	public MiniWebServerThreadPoolExecutor(
	int corePoolSize,
	int maximumPoolSize,
	long keepAliveTime,
	TimeUnit unit,
	int workQueueCapacity,
	ThreadFactory threadFactory)
	{
	super(corePoolSize,
	maximumPoolSize,
	keepAliveTime,
	unit,
	new MiniWebServerBlockingQueue<Runnable>(workQueueCapacity),
	threadFactory);
	}
	}

	@SuppressWarnings("hiding")
	private class MiniWebServerBlockingQueue<Runnable>
	extends LinkedBlockingQueue<Runnable>
	{
	private static final long serialVersionUID = -3943671634425379250L;

	/**
	* Constructor
	*
	* @param capacity Capacity of the queue.
	*/
	public MiniWebServerBlockingQueue(int capacity)
	{
	super(capacity);
	}
	}

	/**
	* Class to store and determine MIME types - RFC2616 Section 19.4.
	*/
	private class MimeType
	{
	private boolean isBinary;
	private String type;
	public static final String HTML_STR = "text/html";
	public static final String JSON_STR = "application/json";
	public static final String TEXT_STR = "text/plain";

	/**
	* Constructor
	*
	* @param isBinary States if we are a binary type.
	* @param type The type we are.
	*/
	public MimeType(boolean isBinary, String type)
	{
	this.isBinary = isBinary;
	this.type = type;
	}

	/**
	* States if we are a binary type.
	*
	* @return true or false.
	*/
	public boolean isBinary()
	{
	return isBinary;
	}

	/**
	* States the MIME type.
	*
	* @return The type.
	*/
	public String getType()
	{
	return type;
	}
	}

	/**
	* Factory to create MimeType's.
	*/
	private class MimeTypeFactory
	{
	public MimeType HTML = new MimeType(false, MimeType.HTML_STR);
	public MimeType JSON = new MimeType(false, MimeType.JSON_STR);
	public MimeType TEXT = new MimeType(false, MimeType.TEXT_STR);

	/**
	* Try to guess the content type from the filename.
	*
	* @param name Name of the file to guess.
	* @return Guessed MIME type text.
	*/
	public MimeType guessContentTypeFromName(String name)
	{
	if (name.endsWith(".html") \|\| name.endsWith(".htm"))
	{
	return new MimeType(false, MimeType.HTML_STR);
	}
	else if (name.endsWith(".txt") \|\| name.endsWith(".java"))
	{
	return new MimeType(false, "text/plain");
	}
	else if (name.endsWith(".gif"))
	{
	return new MimeType(true, "image/gif");
	}
	else if (name.endsWith(".class"))
	{
	return new MimeType(true, "application/octet-stream");
	}
	else if (name.endsWith(".jpg") \|\| name.endsWith(".jpeg"))
	{
	return new MimeType(true, "image/jpeg");
	}
	else if (name.endsWith(".js"))
	{
	return new MimeType(false, "text/javascript; charset=UTF-8");
	}
	else if (name.endsWith(".css"))
	{
	return new MimeType(false, "text/css");
	}
	else if (name.endsWith(".png"))
	{
	return new MimeType(true, "image/png");
	}
	else if (name.endsWith(".otf"))
	{
	//return new MimeType(true, "vnd.oasis.opendocument.formula-template"); // http://www.iana.org/assignments/media-types/application/vnd.oasis.opendocument.formula-template
	return new MimeType(true, "font/opentype"); // Chrome 'no winge' with this.
	}
	else if (name.endsWith(".ico"))
	{
	return new MimeType(true, "image/vnd.microsoft.icon");
	}
	else if (name.endsWith(".swf"))
	{
	return new MimeType(true, "application/x-shockwave-flash");
	}
	else
	{
	return new MimeType(false, MimeType.HTML_STR);
	}
	}
	}
	}
	/*
	* FreeSpace JNI C implementation.
	* © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
	*/
	@charset "UTF-8";

	body {
	font-family: sans-serif;
	background-color: lightgoldenrodyellow;
	text-align: center;
	}
	/*
	* FreeSpace JNI C implementation.
	* © G J Barnard 2013 - Attribution-NonCommercial-ShareAlike 3.0 Unported - http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_GB.
	*
	* When running standalone, pass in filepath, i.e. '/'.
	*
	* Using Java7 on user account 'demo' with a sub folder of 'Java' so adjust the following as required.
	* Include the JNI headers etc.: export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-armhf
	* Compile to object file: gcc -fPIC -c miniwebserver_FreeSpace.c -I $JAVA_HOME/include
	* Compile to library: gcc miniwebserver_FreeSpace.o -shared -o libfreespace.so -Wl,-soname,freespace
	* Compile the Java class that uses FreeSpace which loads libfreespace.so: javac miniwebserver/FreeSpaceMiniWebServer.java
	* Tell the system where to find the libfreespace.so dynamic library: export LD_LIBRARY_PATH=/home/demo/Java
	* Run the program: java miniwebserver/FreeSpaceMiniWebServer
	*/

	#include "miniwebserver_FreeSpace.h"
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/vfs.h>
	#include <stdio.h>
	#include <errno.h>
	#include <time.h>
	#include <stdlib.h>

	int calcfreespace(const char *device);
	char* displaydetails();
	char* displayfreespace();
	int exitcode;
	char result[1024];
	char hostname[128];
	struct stat sbuf;
	struct statfs buf;
	char* thedevice;
	extern char* ctime();

	main(argc, argv)
	int argc;
	char **argv;
	{
	if (argc != 2) {
	fprintf(stderr, "usage: us filesys-name\n");
	exitcode = 1;
	}
	else if (calcfreespace(argv[1]) == 0)
	{
	printf(displaydetails());
	printf("\n");
	printf(displayfreespace());
	printf("\n");
	}
	else
	{
	printf(result);
	printf("\n");
	}

	exit(exitcode);
	}

	int calcfreespace(const char *device)
	{
	if (stat(device, &sbuf) < 0) {
	sprintf(result, "stat error");
	exitcode = 2;
	} else {
	if (statfs(device, &buf) < 0) {
	sprintf(result, "statfs error, errno is: %d", errno);
	exitcode = 2;
	} else {
	hostname[127] = '\0';
	gethostname(&hostname, 127);

	exitcode = 0;
	thedevice = device;
	}
	}

	return exitcode;
	}

	char* displaydetails()
	{
	if (exitcode == 0)
	{
	sprintf(result, "%s:\tblocks %u\tfree blocks %u\tblock size %u\tavailable space %u\tfree inodes %u", thedevice, buf.f_blocks, buf.f_bfree, sbuf.st_blksize, buf.f_bavail, buf.f_ffree);
	}

	return result;
	}

	char* displayfreespace()
	{
	unsigned long freebytes;

	if (exitcode == 0)
	{
	long timevalue;
	time(&timevalue);

	freebytes = buf.f_bavail * sbuf.st_blksize;
	sprintf(result, "Available space on %s %lu bytes %luK %fMB %fGB at %s on %s", thedevice, freebytes, (freebytes) / 1024, ((freebytes) / 1024.0) / 1024.0, (((freebytes) / 1024.0) / 1024.0) / 1024.0, ctime(&timevalue), hostname);
	}

	return result;
	}

	JNIEXPORT jstring JNICALL Java_miniwebserver_FreeSpace_getFreeSpace
	(JNIEnv *env, jclass cls, jstring device)
	{
	if (calcfreespace((*env)->GetStringUTFChars(env, device, 0)) == 0)
	{
	return (*env)->NewStringUTF(env, displayfreespace());
	}
	else
	{
	return (*env)->NewStringUTF(env, result);
	}
	}