Socket实战之七 使用Socket通信传输文件

http://blog.csdn.net/kongxx/article/details/7319410
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。

[java] view plaincopyprint?
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
[java] view plaincopyprint?
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