Java Socket实战之七 使用Socket通信传输文件

本文地址：http://blog.csdn.net/kongxx/article/details/7319410

Java Socket实战之一 单线程通信

Java Socket实战之二 多线程通信

Java Socket实战之三 传输对象

Java Socket实战之四 传输压缩对象

Java Socket实战之五 使用加密协议传输对象

Java Socket实战之六 使用NIO包实现Socket通信

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会发一个文件。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。