ファイルをダウンロードさせるだけのHttpd

Httpd.java

import java.io.File;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;

import com.sun.net.httpserver.HttpServer;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpContext;

public class Httpd {
    public static class FileDownloadHandler implements HttpHandler {
	
	private File basedir;
	
	public FileDownloadHandler(File basedir) throws IOException {
	    if (!basedir.isDirectory()) {
		throw new IOException(basedir.getPath() + " is not directory");
	    }
	    this.basedir = basedir;
	}
	
	public void handle(HttpExchange exchange) {
	    String context = exchange.getHttpContext().getPath();
	    String request = exchange.getRequestURI().getPath();
	    String path = request.substring(context.length(), request.length());

	    try {
		File file = new File(basedir, path);
		if (file.isFile() && file.canRead()) {
		    exchange.getResponseHeaders().add("Content-Type", "application/octet-stream");
		    exchange.sendResponseHeaders(200, file.length());
		    OutputStream os = exchange.getResponseBody();
		    InputStream is = new FileInputStream(file);
		    int b;
		    while ((b = is.read()) != -1) {
			os.write(b);
		    }
		    os.close();
		    is.close();
		}
		else {
		    String message = new StringBuilder()
			.append("<h1>404 Not Found</h1>")
			.append(exchange.getRequestURI() + " - そんなファイルない．")
			.toString();
		    exchange.getResponseHeaders().add("Content-Type", "text/html");
		    exchange.sendResponseHeaders(404, message.getBytes().length);
		    OutputStream os = exchange.getResponseBody();
		    os.write(message.getBytes());
		    os.close();
		}
	    } catch (IOException e) {
		e.printStackTrace();
	    }
	}
    }
    
    public static void main(String[] args) throws Exception {
	InetSocketAddress addr = new InetSocketAddress(8080);
	HttpServer server = HttpServer.create(addr, 0);
	System.err.println("[HTTPD] Started on " + addr);
	server.createContext("/", new FileDownloadHandler(new File("/tmp/hoge")));
	server.start();
    }
}