java socket 模拟im 即时通讯
自己想了一下怎么实现,就写了,没有深究是否合理.更多处理没有写下去,例如收件人不在线,应该保存在数据库,等下一次连接的时候刷新map,再把数据发送过去,图片发送也没有做,也没有用json格式
socket很奇怪,我用客户端连接上了服务器,没有发送消息的情况下,断开电脑网络,是不会出现问题,然后在把电脑网络连接上,通讯依然正常,正常断开也不出问题,但是用idea直接按stop键,那么服务端就会出问题了,读取事件会一直为true,造成死循环,消耗CPU,所以必须要判断一下客户端连接是否断开了
只需要把客户端代码启动几个,修改一些userName以及收件人,就可以测试,实现类似QQ微信即时通讯,聊天功能
服务端代码
package serversocketchannel; 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.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; import java.util.Iterator; import java.util.concurrent.ConcurrentHashMap; /** * * @author ZhenWeiLai * */ public class ServerSocketChannelNonBlocking { 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<String,SocketChannel> 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 void main(String[] args) { service(); } private static void service(){ 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<SelectionKey> 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 static String 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(); return charset.decode(byteBuffer).toString(); } //写出 private static void handleWrite(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(); } } } }
客户端代码
package socketchannel; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.InetSocketAddress; import java.net.SocketAddress; import java.nio.ByteBuffer; import java.nio.channels.ClosedChannelException; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; import java.util.Iterator; /** * Created by lzw on 17-2-28. */ public class SocketChannelNonBlockingClient { private static Charset charset = Charset.forName("GBK"); private static ByteBuffer receiveBuffer = ByteBuffer.allocate(10240); private static ByteBuffer sendBuffer = ByteBuffer.allocate(10240); private static SocketChannel socketChannel = null; private static Selector selector = null; private static String userName = "client1";//客户端名 private static String targetName = "client2";//收件人名 public static void main(String[] args) { try { socketChannel = SocketChannel.open(); //连接到服务端 SocketAddress socketAddress = new InetSocketAddress("19.95.103.112",8000); selector = Selector.open();//实例化一个选择器 socketChannel.configureBlocking(false);//设置为非阻塞 //先监听一个连接事件 socketChannel.register(selector,SelectionKey.OP_CONNECT); //连接 socketChannel.connect(socketAddress); //jdk 1.8的lambda表达式，用一个线程监控控制台输入 new Thread(()->{ try { receiveFromUser(); } catch (IOException e) { e.printStackTrace(); } }).start(); talk(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private static void talk(){ try { while(true){ selector.select();//阻塞直到连接事件 Iterator<SelectionKey> readyKeys = selector.selectedKeys().iterator(); while(readyKeys.hasNext()){ SelectionKey key =readyKeys.next(); if(key.isConnectable()){ //非阻塞的情况下可能没有连接完成，这里调用finishConnect阻塞至连接完成 socketChannel.finishConnect(); //连接完成以后，先发送自己的userName以便保存在服务端的客户端map里面 synchronized (sendBuffer){ SocketChannel socketChannel1 = (SocketChannel)key.channel(); sendBuffer.clear(); sendBuffer.put(charset.encode(userName)); send(socketChannel1); socketChannel.register(selector,SelectionKey.OP_READ);//仅监听一个读取事件 } }else if(key.isReadable()){ //处理读事件 receive(key); } readyKeys.remove(); } } } catch (ClosedChannelException e) { try { socketChannel.close(); } catch (IOException e1) { e1.printStackTrace(); } e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } /** * 从控制台获取用户输入 * @throws IOException */ private static void receiveFromUser() throws IOException{ //阻塞直到控制台有输入 BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); for(String msg = br.readLine();msg!=null&&!msg.equals("bye");msg = br.readLine()){ //同步锁避免线程竞争 synchronized (sendBuffer) { sendBuffer.clear(); //编码 sendBuffer.put(charset.encode(msg)); //分割副 sendBuffer.put(charset.encode("->")); //目标名 sendBuffer.put(charset.encode(targetName)); send(socketChannel); } } } /** * 接收服务端的数据 * @param key */ private static void receive(SelectionKey key) throws IOException { //获取服务端的channel SocketChannel channel = (SocketChannel) key.channel(); //为写入缓冲器做准备position=0,limit=capacity receiveBuffer.clear(); //从服务端的channel把数据读入缓冲器 channel.read(receiveBuffer); //position=0,limit=有效下标最后一位 receiveBuffer.flip(); //解码 String msg = charset.decode(receiveBuffer).toString(); //输出到控制台 System.out.println(msg); } /** * 发送到服务端 */ private static void send(SocketChannel sendChannel) throws IOException { if(sendBuffer.remaining()!=0){ synchronized (sendBuffer){ sendBuffer.flip(); sendChannel.write(sendBuffer); } } } }
