java im即时通讯_java socket 模拟im 即时通讯

packageserversocketchannel;importjava.io.IOException;importjava.net.InetSocketAddress;importjava.nio.ByteBuffer;importjava.nio.channels.SelectionKey;importjava.nio.channels.Selector;importjava.nio.channels.ServerSocketChannel;importjava.nio.channels.SocketChannel;importjava.nio.charset.Charset;importjava.util.Iterator;importjava.util.concurrent.ConcurrentHashMap;/***

*@authorZhenWeiLai

**/

public classServerSocketChannelNonBlocking {private static ServerSocketChannel serverSocketChannel = null;private static Charset charset = Charset.forName("GBK");//设置编码集,用于编码,解码

private static Selector selector = null;//保存客户端的map

private static final ConcurrentHashMap clientSockets = new ConcurrentHashMap<>();static{try{

serverSocketChannel=ServerSocketChannel.open();

serverSocketChannel.socket().setReuseAddress(true);

serverSocketChannel.socket().bind(new InetSocketAddress(8000));

serverSocketChannel.configureBlocking(false);//设置为非阻塞

selector = Selector.open();//实例化一个选择器

} catch(IOException e) {

e.printStackTrace();

}

}public static voidmain(String[] args) {

service();

}private static voidservice(){

SocketChannel clientChannel= null;

SelectionKey selectionKey= null;

SocketChannel targetChannel= null;try{

serverSocketChannel.register(selector,SelectionKey.OP_ACCEPT);//服务端监听连接

while(true){

selector.select();//阻塞至有新的连接就开始处理

Iterator selectionKeys =selector.selectedKeys().iterator();while(selectionKeys.hasNext()){

selectionKey=selectionKeys.next();if(selectionKey.isAcceptable()){//如果事件是连接事件

ServerSocketChannel serverChannel = (ServerSocketChannel)selectionKey.channel();//获取事件绑定的channel

clientChannel = serverChannel.accept();//连接获取带客户端信息的socketChannel

clientChannel.configureBlocking(false);//客户设置为非阻塞,因为非阻塞才支持选择器.避免盲等浪费资源

ByteBuffer byteBuffer = ByteBuffer.allocate(1024);//作为每一个客户端的附件缓冲器

/*** 只监听读事件,这里千万别监听写事件,因为只要连接有效,那么写事件会一直为true,导致死循环,很耗资源

* 可以跟serverSocket用同一个选择器,因为绑定的channel不同*/clientChannel.register(selector,SelectionKey.OP_READ,byteBuffer);

}else if(selectionKey.isReadable()){//只要有客户端写入,那么就可以处理//获取客户端附件,也就是写入的数据

ByteBuffer byteBuffer =(ByteBuffer)selectionKey.attachment();//从selectionKey获取客户端的channel

SocketChannel socketChannel =(SocketChannel)selectionKey.channel();//把附件读出,解码为字符串

String msg =read(socketChannel,byteBuffer);//这里用了->分割收件人,->后面跟着的字符串是收件人

if(msg.indexOf("->")!=-1){//内容

String content = msg.substring(0,msg.lastIndexOf("->"));//从map里获取收件人的socket

targetChannel = clientSockets.get(msg.substring(msg.lastIndexOf("->")+2));//实例化一个缓冲区,用来写出到收件人的socketChannel

ByteBuffer temp = ByteBuffer.allocate(1024);

temp.put(charset.encode(content));//写出

handleWrite(targetChannel,temp);

}else{//如果内容没有收件人,那么视为第一次连接,客户端发过来的userName,作为KEY存入MAP

clientSockets.put(msg,socketChannel);

}

}

selectionKeys.remove();

}

}

}catch(IOException e) {try{if(selectionKey!=null)selectionKey.cancel();if(clientChannel!=null){

clientChannel.shutdownInput();

clientChannel.shutdownOutput();

clientChannel.close();

}if(targetChannel!=null){

targetChannel.shutdownInput();

targetChannel.shutdownOutput();

targetChannel.close();

}

}catch(IOException e1) {//TODO Auto-generated catch block

e1.printStackTrace();

}

e.printStackTrace();

}

}private staticString read(SocketChannel socketChannel,ByteBuffer byteBuffer){//重置position limit为写入做准备

byteBuffer.clear();try{int flag =socketChannel.read(byteBuffer);//判断客户端是否断开连接

if(flag==-1){//如果客户端无故断开,一定要关闭,否则读取事件一直为true造成死循环,非常耗资源

socketChannel.close();

}

}catch(IOException e) {try{

socketChannel.close();

}catch(IOException e1) {

e1.printStackTrace();

}

e.printStackTrace();

}//position =0 limit等于有效下标,为写出做准备

byteBuffer.flip();returncharset.decode(byteBuffer).toString();

}//写出

private static voidhandleWrite(SocketChannel socketChannel,ByteBuffer byteBuffer){synchronized(byteBuffer) {

byteBuffer.flip();try{

socketChannel.write(byteBuffer);

}catch(IOException e) {try{

socketChannel.close();

}catch(IOException e1) {

e1.printStackTrace();

}

e.printStackTrace();

}

}

}

}