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！
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