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。
 */
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)：

以上就是本文的全部内容，希望对大家的学习有所帮助。