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 {

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。

*/

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 {

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

*/

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

if(i

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)：

以上就是本文的全部内容，希望对大家的学习有所帮助。