Java基于TCP方式的二进制文件传输

2019-11-26 14:40:34

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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)：