WebServer.java

WebServer.java

import java.io.*;
import java.net.*;
import java.util.ArrayList;

class WebServer {
    // this is the port the web server listens on
    private static final int PORT_NUMBER = 8080;

    // main entry point for the application
    public static void main(String args[]) {
        try {
            // open socket
            ServerSocket serverSocket = new ServerSocket(PORT_NUMBER);

            // start listener thread
            Thread listener = new Thread(new SocketListener(serverSocket));
            listener.start();

            // message explaining how to connect
            System.out.println("To connect to this server via a web browser, try \"http://127.0.0.1:8080/{url to retrieve}\"");

            // wait until finished
            System.out.println("Press enter to shutdown the web server...");

            // kill listener thread
            listener.interrupt();

        } catch (Exception e) {
            System.err.println("WebServer::main - " + e.toString());
        }
    }
}

class SocketListener implements Runnable {
    private ServerSocket serverSocket;

    public SocketListener(ServerSocket serverSocket) {
        this.serverSocket = serverSocket;
    }

    // this thread listens for connections, launches a seperate socket connection
    //  thread to interact with them
    public void run() {
        while (true) {
            try {
                Socket clientSocket = serverSocket.accept();
                Thread connection = new Thread(new SocketConnection(clientSocket));
                connection.start();
                Thread.yield();
            } catch (IOException e) {
                if (!this.serverSocket.isClosed()) {
                    System.err.println("SocketListener::run - " + e.toString());
                }
            }
        }
    }
}

class HttpRequest {
    private String method;
    private String path;

    public HttpRequest() {
    }

    public String getMethod() {
        return method;
    }

    public void setMethod(String method) {
        this.method = method;
    }

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }
}

class SocketConnection implements Runnable {
    private final String HTTP_LINE_BREAK = "\r\n";

    private Socket clientSocket;

    public SocketConnection(Socket clientSocket) {
        this.clientSocket = clientSocket;
    }

    // one of these threads is spawned and used to talk to each connection
    public void run() {
        try {
            BufferedReader request = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
            PrintWriter response = new PrintWriter(this.clientSocket.getOutputStream(), true);
            this.handleConnection(request, response);
        } catch (Exception e) {
            System.err.println("SocketConnection::run - " + e.toString());
        }
    }

    // TODO: implement your HTTP protocol for this server within this method
    private void handleConnection(BufferedReader reader, PrintWriter response) throws IOException {
        try {
            /*
             *
             * TODO: implement your web server here
             *
             * Tasks:
             * ------
             * 1.) Figure out how to parse the HTTP reader header
             * 2.) Figure out how to open files
             * 3.) Figure out how to create an HTTP responseHtml header
             * 4.) Figure out how to return resources (i.e. files)
             *
             */
            // EXAMPLE: code prints the web reader
            HttpRequest request = this.readHTTPHeader(reader, new HttpRequest());
            ArrayList<String> folders = new ArrayList<>();
            folders.add("add");
            folders.add("helloworld");
            folders.add("subdirectory");
            // Start sending our reply, using the HTTP 1.1 protocol
            response.print("HTTP/1.1 200 \r\n"); // Version & status code
            response.print("Content-Type: text/html; charset=utf-8\r\n"); // The type of data
            response.print("Connection: close\r\n"); // Will close stream
            response.print("\r\n"); // End of headers

            if (folders.contains(request.getPath().replaceFirst("/", ""))) {
                if (request.getPath().replace("/", "").equals("subdirectory")) {
                    response.print(responseDirectory(null));
                } else response.println(this.responseHtmlFile(request.getPath()));
            } else if (request.getPath().contains("subdirectory")) {
                response.print(responseDirectory(request.getPath().replace("/subdirectory/", "")));
            } else {
                StringBuilder builder = new StringBuilder();
                builder.append("<a href=\"/add\">add</a><br>");
                builder.append("<a href=\"/helloworld\">helloworld</a><br>");
                builder.append("<a href=\"/subdirectory\">subdirectory</a><br>");
                response.print(builder.toString());
            }
            response.close();
            reader.close();
        } finally {
            // close the socket, no keep alives
            this.clientSocket.close();
        }
    }

    private String responseDirectory(String sub) throws IOException {
        if (sub == null) {
            StringBuilder builder = new StringBuilder();
            String dir = System.getProperty("user.dir") + "/" + "webroot" + "/subdirectory";

            File directory = new File(dir);
            //get all the files from a directory
            File[] fList = directory.listFiles();
            for (File file : fList) {
                if (file.isFile()) {
                    builder.append("<a href=\"/subdirectory/" + file.getName() + "\">" + file.getName() + "</a><br>");
                }
            }
            return builder.toString();
        }

        return responseHtml(System.getProperty("user.dir") + "/" + "webroot" + "/subdirectory/" + sub);
    }

    private String responseHtmlFile(String path) throws IOException {
        String dir = System.getProperty("user.dir") + "/" + "webroot" + "/" + path + "/" + "index.html";
        return responseHtml(dir);
    }

    private String responseHtml(String dir) throws IOException {

        FileReader fr = new FileReader(dir);
        BufferedReader br = new BufferedReader(fr);

        String sCurrentLine;
        StringBuilder content = new StringBuilder();
        try {
            while ((sCurrentLine = br.readLine()) != null) {
                content.append(sCurrentLine);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            br.close();
            fr.close();
        }
        return content.toString();
    }

    private HttpRequest readHTTPHeader(BufferedReader reader, HttpRequest request) {
        String message = "";
        String line = "";
        int read = 0;
        while ((line != null) && (!line.equals(this.HTTP_LINE_BREAK))) {
            line = this.readHTTPHeaderLine(reader);
            if (read == 0) {
                String[] data = line.split(" ");
                request.setMethod(data[0]);
                request.setPath(data[1]);
            }
            message += line;
            read++;
        }
        return request;
    }

    private String readHTTPHeaderLine(BufferedReader reader) {
        String line = "";
        try {
            line = reader.readLine() + this.HTTP_LINE_BREAK;
        } catch (IOException e) {
            System.err.println("SocketConnection::readHTTPHeaderLine: " + e.toString());
            line = "";
        }
        return line;
    }
}