Java使用Socket通信传输文件的方法示例

本文实例讲述了Java使用Socket通信传输文件的方法。分享给大家供大家参考，具体如下：

前面几篇文章介绍了使用Java的Socket编程和NIO包在Socket中的应用，这篇文章说说怎样利用Socket编程来实现简单的文件传输。

这里由于前面一片文章介绍了NIO在Socket中的应用，所以这里在读写文件的时候也继续使用NIO包，所以代码看起来会比直接使用流的方式稍微复杂一点点。

下面的示例演示了客户端向服务器端发送一个文件，服务器作为响应给客户端回发一个文件。这里准备两个文件E:/test/server_send.log和E:/test/client.send.log文件，在测试完毕后在客户端和服务器相同目录下会多出两个文件E:/test/server_receive.log和E:/test/client.receive.log文件。

下面首先来看看Server类，主要关注其中的sendFile和receiveFile方法。

package com.googlecode.garbagecan.test.socket.nio;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;
public class MyServer4 {
 private final static Logger logger = Logger.getLogger(MyServer4.class.getName());
 public static void main(String[] args) {
   Selector selector = null;
   ServerSocketChannel serverSocketChannel = null;
   try {
     // Selector for incoming time requests
     selector = Selector.open();
     // Create a new server socket and set to non blocking mode
     serverSocketChannel = ServerSocketChannel.open();
     serverSocketChannel.configureBlocking(false);
     // Bind the server socket to the local host and port
     serverSocketChannel.socket().setReuseAddress(true);
     serverSocketChannel.socket().bind(new InetSocketAddress(10000));
     // Register accepts on the server socket with the selector. This
     // step tells the selector that the socket wants to be put on the
     // ready list when accept operations occur, so allowing multiplexed
     // non-blocking I/O to take place.
     serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
     // Here's where everything happens. The select method will
     // return when any operations registered above have occurred, the
     // thread has been interrupted, etc.
     while (selector.select() > 0) {
       // Someone is ready for I/O, get the ready keys
       Iterator<SelectionKey> it = selector.selectedKeys().iterator();
       // Walk through the ready keys collection and process date requests.
       while (it.hasNext()) {
         SelectionKey readyKey = it.next();
         it.remove();
         // The key indexes into the selector so you
         // can retrieve the socket that's ready for I/O
         doit((ServerSocketChannel) readyKey.channel());
       }
     }
   } catch (ClosedChannelException ex) {
     logger.log(Level.SEVERE, null, ex);
   } catch (IOException ex) {
     logger.log(Level.SEVERE, null, ex);
   } finally {
     try {
       selector.close();
     } catch(Exception ex) {}
     try {
       serverSocketChannel.close();
     } catch(Exception ex) {}
   }
 }
 private static void doit(final ServerSocketChannel serverSocketChannel) throws IOException {
   SocketChannel socketChannel = null;
   try {
     socketChannel = serverSocketChannel.accept();
     receiveFile(socketChannel, new File("E:/test/server_receive.log"));
     sendFile(socketChannel, new File("E:/test/server_send.log"));
   } finally {
     try {
       socketChannel.close();
     } catch(Exception ex) {}
   }
 }
 private static void receiveFile(SocketChannel socketChannel, File file) throws IOException {
   FileOutputStream fos = null;
   FileChannel channel = null;
   try {
     fos = new FileOutputStream(file);
     channel = fos.getChannel();
     ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
     int size = 0;
     while ((size = socketChannel.read(buffer)) != -1) {
       buffer.flip();
       if (size > 0) {
         buffer.limit(size);
         channel.write(buffer);
         buffer.clear();
       }
     }
   } finally {
     try {
       channel.close();
     } catch(Exception ex) {}
     try {
       fos.close();
     } catch(Exception ex) {}
   }
 }
 private static void sendFile(SocketChannel socketChannel, File file) throws IOException {
   FileInputStream fis = null;
   FileChannel channel = null;
   try {
     fis = new FileInputStream(file);
     channel = fis.getChannel();
     ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
     int size = 0;
     while ((size = channel.read(buffer)) != -1) {
       buffer.rewind();
       buffer.limit(size);
       socketChannel.write(buffer);
       buffer.clear();
     }
     socketChannel.socket().shutdownOutput();
   } finally {
     try {
       channel.close();
     } catch(Exception ex) {}
     try {
       fis.close();
     } catch(Exception ex) {}
   }
 }
}

下面是Client程序代码，也主要关注sendFile和receiveFile方法

package com.googlecode.garbagecan.test.socket.nio;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SocketChannel;
import java.util.logging.Level;
import java.util.logging.Logger;
public class MyClient4 {
 private final static Logger logger = Logger.getLogger(MyClient4.class.getName());
 public static void main(String[] args) throws Exception {
   new Thread(new MyRunnable()).start();
 }
 private static final class MyRunnable implements Runnable {
   public void run() {
     SocketChannel socketChannel = null;
     try {
       socketChannel = SocketChannel.open();
       SocketAddress socketAddress = new InetSocketAddress("localhost", 10000);
       socketChannel.connect(socketAddress);
       sendFile(socketChannel, new File("E:/test/client_send.log"));
       receiveFile(socketChannel, new File("E:/test/client_receive.log"));
     } catch (Exception ex) {
       logger.log(Level.SEVERE, null, ex);
     } finally {
       try {
         socketChannel.close();
       } catch(Exception ex) {}
     }
   }
   private void sendFile(SocketChannel socketChannel, File file) throws IOException {
     FileInputStream fis = null;
     FileChannel channel = null;
     try {
       fis = new FileInputStream(file);
       channel = fis.getChannel();
       ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
       int size = 0;
       while ((size = channel.read(buffer)) != -1) {
         buffer.rewind();
         buffer.limit(size);
         socketChannel.write(buffer);
         buffer.clear();
       }
       socketChannel.socket().shutdownOutput();
     } finally {
       try {
         channel.close();
       } catch(Exception ex) {}
       try {
         fis.close();
       } catch(Exception ex) {}
     }
   }
   private void receiveFile(SocketChannel socketChannel, File file) throws IOException {
     FileOutputStream fos = null;
     FileChannel channel = null;
     try {
       fos = new FileOutputStream(file);
       channel = fos.getChannel();
       ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
       int size = 0;
       while ((size = socketChannel.read(buffer)) != -1) {
         buffer.flip();
         if (size > 0) {
           buffer.limit(size);
           channel.write(buffer);
           buffer.clear();
         }
       }
     } finally {
       try {
         channel.close();
       } catch(Exception ex) {}
       try {
         fos.close();
       } catch(Exception ex) {}
     }
   }
 }
}

首先运行MyServer4类启动监听，然后运行MyClient4类来向服务器发送文件以及接受服务器响应文件。运行完后，分别检查服务器和客户端接收到的文件。

希望本文所述对大家java程序设计有所帮助。