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。