Java NIO Demo

Java NIO Demo 在读Amoeba源码的时候，里面采用java NIO进行通信管理，以前也了解过一些关于这方面的知识但是都不太系统，最近两天抽时间对这块进行一下扫盲。我主要参考以下两篇文章，个人认为这两篇文章还是不错的入门级文章，讲的比较通俗易懂。
1.http://www.ibm.com/developerworks/cn/education/java/j-nio/section11.html
比较系统的讲述了Channel（通道）、Buffer（缓冲区）、position，limit，capacity in buffer等；其示例代码在：
http://code.google.com/p/astudy/source/browse/trunk/applications/astudy/nio/MultiPortEcho.java?spec=svn141&r=141下

2.http://tutorials.jenkov.com/java-nio/index.html
这个站点也是一个不错的入门级别介绍，虽然是e文，但讲解的比较细致。

3.我的demo
这个小例子，模拟了一个echo服务，客户端向echo服务器发送一段信息，echo收到信息后，返回给客户端，然后，连接关闭。代码如下：

/***************************************/

客户端代码：

package com.zxl.channel;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.SelectionKey;

import java.nio.channels.Selector;

import java.nio.channels.SocketChannel;

import java.nio.charset.Charset;

import java.util.Set;

public class EchoClient {

/**

* @param args

* @throws IOException

public static void main(String[] args) throws IOException {

SocketChannel channel = SocketChannel.open();

channel.configureBlocking(false);

InetSocketAddress s = new InetSocketAddress("localhost",2000);

channel.connect(s);

Selector selector = Selector.open();

channel.register(selector, SelectionKey.OP_CONNECT|SelectionKey.OP_READ);

Charset charset=Charset.forName("GBK");

boolean isFinished = false;

while(!isFinished){

int num = selector.select();

if(num>0){

Set<SelectionKey> keys = selector.selectedKeys();

for(SelectionKey k:keys){

if(k.isConnectable()){

SocketChannel sc = (SocketChannel) k.channel();

sc.configureBlocking(false);

sc.finishConnect();

sc.register(selector, SelectionKey.OP_READ);

ByteBuffer echoBuffer = ByteBuffer.allocate(1024);

ByteBuffer info =charset.encode("好了克隆技术杜洛克防水堵漏开发!");

echoBuffer.put(info);

echoBuffer.flip();

sc.write(echoBuffer);

echoBuffer.clear();

}else if (k.isValid() && k.isReadable()) {

ByteBuffer echoBuffer = ByteBuffer.allocate(1024);

SocketChannel sc = (SocketChannel) k.channel();

sc.read(echoBuffer);

echoBuffer.flip();

System.out.println("echo server return:"+charset.decode(echoBuffer).toString());

echoBuffer.clear();

isFinished = true;

k.cancel();

sc.close();

selector.close();

}

/*********************************************/

服务端代码：

package com.zxl.channel;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.net.ServerSocket;

import java.nio.ByteBuffer;

import java.nio.channels.SelectionKey;

import java.nio.channels.Selector;

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

import java.nio.charset.Charset;

import java.util.Iterator;

import java.util.Set;

public class MultiPortEchoServer {

private Charset charset=Charset.forName("GBK");

private int[] ports;

/**

* @param args

public static void main(String[] args) {

int[] ps = {2000,2001}; //默认监听2000,2001端口

new MultiPortEchoServer(ps);

}

public MultiPortEchoServer(int[] ports){

this.ports = ports;

try {

go();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

public void go() throws IOException{

Selector selector = Selector.open();

for(int i=0;i<ports.length;i++){

ServerSocketChannel channel = ServerSocketChannel.open();

channel.configureBlocking(false);

ServerSocket socket = channel.socket();

InetSocketAddress address = new InetSocketAddress("localhost",ports[i]);

socket.bind(address);

//注册接受连接事件

channel.register(selector, SelectionKey.OP_ACCEPT);

System.out.println( "Going to listen on "+ports[i] );

}

while(true){

int num = selector.select();

Set<SelectionKey> keys = selector.selectedKeys();

Iterator<SelectionKey> iter = keys.iterator();

while(iter.hasNext()){

SelectionKey key = iter.next();

if((key.readyOps()&SelectionKey.OP_ACCEPT)==SelectionKey.OP_ACCEPT){

ServerSocketChannel ssc = (ServerSocketChannel) key.channel();

SocketChannel sc = ssc.accept();

sc.configureBlocking(false);

sc.register(selector, SelectionKey.OP_READ);

iter.remove();

}else if((key.readyOps()&SelectionKey.OP_READ)==SelectionKey.OP_READ){

SocketChannel sc = (SocketChannel) key.channel();

if(!sc.isOpen()){

selector = Selector.open();

}else{

ByteBuffer echoBuffer = ByteBuffer.allocate(1024);

//int x = sc.read(echoBuffer);

while(sc.read(echoBuffer)>0){

System.out.println( "Echoed "+charset.decode(echoBuffer).toString()+" from "+sc.socket().getInetAddress().getHostAddress() );

echoBuffer.flip();

sc.write(echoBuffer);

echoBuffer.clear();

}

iter.remove();

/*返回信息后关闭连接*/

key.cancel();

sc.close();

}

keys.clear();

}

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