Java基于TCP方式的二进制文件传输

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 * 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。
*/
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
*/
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)：