此人博客挺好的，推荐一个！

一个基于Java Socket协议之上文件传输的完整示例，基于TCP通信完成。

除了基于TCP的二进制文件传输，还演示了JAVA Swing的一些编程技巧，Demo程序

实现主要功能有以下几点：

1.      基于Java Socket的二进制文件传输(包括图片，二进制文件，各种文档work，

         PDF)

2.      SwingWorker集合JProgressBar显示实时传输/接受完成的百分比

3.      其它一些Swing多线程编程技巧

首先来看一下整个Dome的Class之间的关系图：

下面按照上图来详细解释各个类的功能与代码实现：

服务器端：

FileTransferServer类的功能首先是在端口9999创建一个服务器套接字并

开始监听连接。相关代码如下：

 

private void startServer(int port) {
    try {
        serverSocket = new ServerSocket(port);
        System.out.println("Server started at port :" + port);
        while(true) {
            Socket client = serverSocket.accept(); // blocked & waiting for income socket
            System.out.println("Just connected to " + client.getRemoteSocketAddress());
            FileReceiveTask task = new FileReceiveTask(client);
            bar.setValue(0); // reset it now
            task.addPropertyChangeListener(new PropertyChangeListener() {
                public void propertyChange(PropertyChangeEvent evt) {
                    if ("progress".equals(evt.getPropertyName())) {
                        bar.setValue((Integer) evt.getNewValue());
                    }
                }
            });

            task.execute();
        }

    } catch (IOException e) {
        e.printStackTrace();
    }
}

关于PropertyChangeListener, Java提供了一个非常有力的工具类来

 

监控任意Bean Model的数据改变，程序通过添加该监听器实现对

SwingWorker的progress属性值改变的事件捕获，然后更新JProgressBar

实例对象，实现了UI的刷新。FileTransferServer类的完整源代码如下：

 

package com.gloomyfish.socket.tutorial.filetransfer;

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JProgressBar;

public class FileTransferServer extends JFrame implements ActionListener {
    /**
     *
     */
    public final static String START_SVR = "Start";
    public final static String SHUT_DOWN_SVR = "Shut Down";
    public final static String END_FLAG = "EOF";
    private static final long serialVersionUID = 1L;
    private ServerSocket serverSocket;
    private JButton startBtn;
    private JProgressBar bar;
    public FileTransferServer() {
        super("File Server");
        initComponent();
        setupListener();
    }

    private void setupListener() {
        startBtn.addActionListener(this);
    }

    private void initComponent() {
        startBtn = new JButton(START_SVR);
        JPanel progressPanel = new JPanel();
        progressPanel.setLayout(new BoxLayout(progressPanel, BoxLayout.Y_AXIS));
        bar = new JProgressBar();
        bar.setMinimum(0);
        bar.setMaximum(100);
        progressPanel.add(bar);
        getContentPane().setLayout(new BorderLayout());
        JPanel btnPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
        btnPanel.add(startBtn);
        getContentPane().add(btnPanel, BorderLayout.SOUTH);
        getContentPane().add(progressPanel, BorderLayout.CENTER);
    }

    private void startServer(int port) {
        try {
            serverSocket = new ServerSocket(port);
            System.out.println("Server started at port :" + port);
            while(true) {
                Socket client = serverSocket.accept(); // blocked & waiting for income socket
                System.out.println("Just connected to " + client.getRemoteSocketAddress());
                FileReceiveTask task = new FileReceiveTask(client);
                bar.setValue(0); // reset it now
                task.addPropertyChangeListener(new PropertyChangeListener() {
                    public void propertyChange(PropertyChangeEvent evt) {
                        if ("progress".equals(evt.getPropertyName())) {
                            bar.setValue((Integer) evt.getNewValue());
                        }
                    }
                });

                task.execute();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void showSuccess() {
        bar.setValue(100);
        JOptionPane.showMessageDialog(this, "file received successfully!");
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if(START_SVR.equals(e.getActionCommand())) {
            Thread startThread = new Thread(new Runnable() {
                public void run() {
                    startServer(9999);
                }
            });
            startThread.start();
            startBtn.setEnabled(false);
        } else if(SHUT_DOWN_SVR.equals(e.getActionCommand())) {

        } else {
            // do nothing...
        }
    }

    public static void main(String[] args) {
        FileTransferServer server = new FileTransferServer();
        server.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        server.setSize(400, 400);
        server.setResizable(false);
        server.setVisible(true);
    }
}

FileReceiveTask是服务器端的文件接受类：

 

首先从建立的TCP流中得到文件名与文件大小，然后开始接受文件内容字节

并写入创建的文件对象流中，最后验证文件大小与写入的字节流是否相等

最后发送一条消息到文件发送方，告诉对方文件传输完成，可以关闭TCP流。

该类的完整源代码如下：

 

package com.gloomyfish.socket.tutorial.filetransfer;

import java.io.BufferedOutputStream;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.net.Socket;

import javax.swing.SwingWorker;

public class FileReceiveTask extends SwingWorker<Integer, Object> {
    private Socket _mSocket;
    public FileReceiveTask(Socket client) {
        this._mSocket = client;
    }

    @Override
    protected Integer doInBackground() throws Exception {
        // get file meta information
        DataInputStream input = new DataInputStream(_mSocket.getInputStream());
        String fileName = input.readUTF();
        int fileLength = (int)input.readLong(); // number of total bytes
        File file = new File("C:\\Users\\fish\\Downloads" + File.separator + fileName);
        BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(file));
        System.out.println("Received File Name = " + fileName);
        System.out.println("Received File size = " + fileLength/1024 + "KB");

        // start to receive the content of the file and write them
        byte[] content = new byte[2048];
        int offset = 0;
        int numReadBytes = 0;
        while(offset < fileLength && (numReadBytes = input.read(content)) > 0) {
            output.write(content, 0, numReadBytes);
            float precent = 100.0f * ((float)offset)/((float)fileLength);
            setProgress((int)precent);
            offset += numReadBytes;
        }
        System.out.println("numReadBytes = " + numReadBytes);
        if(offset < fileLength) {
            numReadBytes = input.read(content);
            System.out.println("numReadBytes = " + numReadBytes);
            System.out.println("File content error at server side");
        } else {
            System.out.println("File Receive Task has done correctly");
        }
        setProgress(100);

        // tell client to close the socket now, we already receive the file successfully!!
        BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(_mSocket.getOutputStream()));
        bufferedWriter.write("DONE\r\n");
        bufferedWriter.flush();

        // close the file and socket
        output.close();
        _mSocket.close();
        return 100;
    }

}

客户端：

 

FileTransferClient是客户端UI类，用来实现到服务端的连接，然后选择

要传输的文件(图片，PDF，Word文档等各种二进制文件)。如果没有

输入服务器信息，会弹出提示要求输入。端口已经指定为：9999

【send File】按钮会打开文件选择框，用户选择要传输文件以后，创建

FileTransferTask线程，并开始执行文件传送。客户端UI代码如下：

 

package com.gloomyfish.socket.tutorial.filetransfer;

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.net.InetSocketAddress;
import java.net.SocketAddress;

import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JTextField;
/**
 * 我一般写英文注释，偶尔我也会写中文注释，只是觉得写英文
 * 注释跟代码比较统一，无他。
 *
 * @Date 2012-11-30
 * @author fish
 *
 */
public class FileTransferClient extends JFrame implements ActionListener {
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    public final static String SEND_CMD = "Send File";
    public final static int MINIMUM = 0;
    public final static int MAXIMUM = 100;
    // public final static String CONNECT_CMD = "Connect";
    private JButton sendFileBtn;
    private JTextField serverField;
    private JTextField portField;
    private JProgressBar bar;

    public FileTransferClient() {
        super("File Transfer Client");
        initComponents();
    }

    private void initComponents() {
        getContentPane().setLayout(new BorderLayout());
        JPanel progressPanel = new JPanel();
        progressPanel.setLayout(new BoxLayout(progressPanel, BoxLayout.Y_AXIS));
        bar = new JProgressBar();
        progressPanel.add(bar);
        bar.setMinimum(MINIMUM);
        bar.setMaximum(MAXIMUM);
        JPanel serverSettingPanel = new JPanel();
        serverSettingPanel.setLayout(new GridLayout(2,2,5,5));
        serverSettingPanel.setBorder(BorderFactory.createTitledBorder("Server Setting"));
        serverField = new JTextField();
        portField = new JTextField();
        serverSettingPanel.add(new JLabel("Server IP/Host:"));
        serverSettingPanel.add(serverField);
        serverSettingPanel.add(new JLabel("Server Port:"));
        serverSettingPanel.add(portField);

        sendFileBtn = new JButton(SEND_CMD);
        JPanel btnPanel = new JPanel();
        btnPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
        btnPanel.add(sendFileBtn);
        getContentPane().add(serverSettingPanel, BorderLayout.NORTH);
        getContentPane().add(btnPanel, BorderLayout.SOUTH);
        getContentPane().add(progressPanel, BorderLayout.CENTER);
        sendFileBtn.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        if(command.equals(SEND_CMD)) {
            if(checkNull()) {
                JOptionPane.showMessageDialog(this, "Please enter server host and port in order to set up the connection!");
                return;
            }
            JFileChooser chooser = new JFileChooser();
            int status = chooser.showOpenDialog(null);
            if (status == JFileChooser.APPROVE_OPTION) {
                File f = chooser.getSelectedFile();
                SocketAddress address = new InetSocketAddress(getServer(), getPort());
                FileTransferTask task = new FileTransferTask(f, address, this);
                bar.setValue(0);
                task.addPropertyChangeListener(new PropertyChangeListener() {
                    public void propertyChange(PropertyChangeEvent evt) {
                        if ("progress".equals(evt.getPropertyName())) {
                            bar.setValue((Integer) evt.getNewValue());
                        }
                    }
                });
                task.execute(); // 异步task执行
            }
        } else {
            // do nothing
        }
    }

    public void showSuccess() {
        bar.setValue(100);
        JOptionPane.showMessageDialog(this, "file send successfully!");
    }

    public String getServer() {
        return serverField.getText().trim();
    }

    public int getPort() {
        return Integer.parseInt(portField.getText().trim());
    }
    /**
     * make sure the UI already have some correct input information here!!!
     * @return
     */
    private boolean checkNull() {
        String serverName = serverField.getText();
        String port = portField.getText();
        if(serverName == null || serverName.length() == 0 || port == null || port.length() == 0) {
            return true;
        }

        try {
            Integer.parseInt(port); // try to parse it as server port number , validation code.
        } catch(NumberFormatException ne) {
            ne.printStackTrace();
            return true;
        }
        return false;
    }

    public static void main(String[] args) {
        FileTransferClient client = new FileTransferClient();
        client.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        client.setSize(400, 400);
        client.setResizable(false);
        // client.pack();
        client.setVisible(true);
    }

}

FileTransferTask实现的功能主要有：

 

1. 发送文件meta信息到接受方(文件名与文件大小)

2. 读取文件内容字节写入Socket字节流中，发送到接受方

3. 从Socket字节流中读取对方接受完成通知信息，调用弹出文件传输成功信息

该类完全源代码如下：

 

package com.gloomyfish.socket.tutorial.filetransfer;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;
import java.net.SocketAddress;

import javax.swing.SwingWorker;

public class FileTransferTask extends SwingWorker<Integer, Object> {
    private File selectedFile;
    private Socket mSocket;
    private SocketAddress address;
    private FileTransferClient parent;

    public FileTransferTask(File file, SocketAddress address, FileTransferClient owner /*, JProgressBar progress*/) {
        this.address = address;
        this.selectedFile = file;
        mSocket = new Socket();
        this.parent = owner;
    }

    @Override
    protected Integer doInBackground() throws Exception {
        // Get the size of the file
        long length = selectedFile.length();
        if (length > Integer.MAX_VALUE) {
            throw new IOException("Could not completely read file " + selectedFile.getName() + " as it is too long (" + length + " bytes, max supported " + Integer.MAX_VALUE + ")");
        }

        mSocket.connect(address);

        // Create the byte array to hold the file data
        mSocket.setSoLinger(true, 60);
        DataOutputStream dout = new DataOutputStream(mSocket.getOutputStream());
        // now we start to send the file meta info.
        dout.writeUTF(selectedFile.getName());
        dout.writeLong(length);
        dout.flush();
        // end comment
        FileDataPackage pData = new FileDataPackage();
        DataInputStream is = new DataInputStream(new FileInputStream(selectedFile));
        byte[] bytes = new byte[2048];

        // Read in the bytes
        int offset = 0;
        int numRead = 0;
        int fsize = (int)length;
        while (offset < fsize && (numRead=is.read(bytes, 0, bytes.length)) >= 0) {
            pData.setData(bytes, numRead);
            dout.write(pData.getPackageData(), 0, pData.getPackageData().length);
            dout.flush();
            offset += numRead;
            float precent = 100.0f * ((float)offset)/((float)fsize);
            setProgress((int)precent);
        }
        System.out.println("total send bytes = " + offset);
        // Ensure all the bytes have been read in
        if (offset < fsize) {
            throw new IOException("Could not completely transfer file " + selectedFile.getName());
        }
        mSocket.shutdownOutput();

        // receive the file transfer successfully message from connection

        BufferedInputStream streamReader = new BufferedInputStream(mSocket.getInputStream());
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(streamReader));
        String doneMsg = bufferedReader.readLine();
        if("DONE".equals(doneMsg)) {
            parent.showSuccess();
        }
        // Close the file input stream
        setProgress(100);
        // dout.close();
        mSocket.close();
        is.close();
        System.out.println("close it now......");
        return 100;
    }
}

数据包类如下，不解释！

 

 

package com.gloomyfish.socket.tutorial.filetransfer;
/**
 * this is very simple file transfer protocol over TCP socket
 * @date 2012-12-01
 * @author zhigang jia
 *
 */
public class FileDataPackage {

    private int dataLength; // 数据包中数据长度，两个字节
    private byte[] databuff; // 数据包中数据，meici最大不超过2048字节

    public final static byte[] EOF = new byte[]{       'E', 'O','F'};

    public FileDataPackage() {
        dataLength = 0;
        databuff = new byte[2048];
    }

    public byte[] getPackageData() {
        byte[] pData = new byte[dataLength];
        // end comment
        System.arraycopy(databuff, 0, pData, 0, dataLength);
        return pData;
    }

    public void setData(byte[] data, int bsize) {
        dataLength = bsize;
        for(int i=0; i<databuff.length; i++) {
            if(i<bsize) {
                databuff[i] = data[i];
            } else {
                databuff[i] = ' ';
            }
        }
    }
}

每次发送的最大字节数为2048个字节。程序最终运行效果如下(win7 + JDK6u30)：

 

觉得不错，请顶一下啊，谢谢！