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();
}
}
}
}