概述
Netty是Apache团队的又一个优秀的Socket框架，它和mina是一个团队开发的，所以很多思想是相同的，接下来，我们就来实现客户端和服务端的双向通信。
首先，我们定义消息类型：
/**
* 消息类型
* @author 李熠
*
*/
public enum MsgType {
PING,SEND,LOGIN,NO_TARGET
}
分别是心跳、发送、登录、找不到目标
当客户端和服务端连接后，需要向服务端发送登录请求，也就是消息类型：LOGIN，服务端接收到LOGIN请求后，会将客户端加入到队列中，
import java.io.Serializable;
public class Message implements Serializable {
private static final long serialVersionUID = -5756901646411393269L;
private String clientId;//发送者客户端ID
private MsgType type;//消息类型
private String data;//数据
private String targetId;//目标客户端ID
public String getTargetId() {
return targetId;
}
public void setTargetId(String targetId) {
this.targetId = targetId;
}
public String getClientId() {
return clientId;
}
public void setClientId(String clientId) {
this.clientId = clientId;
}
public MsgType getType() {
return type;
}
public void setType(MsgType type) {
this.type = type;
}
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
public Message(){
}
public Message(MsgType type){
this.type = type;
}
}
这类是定义的消息Bean，想服务端发送消息就是发送的这个对象的数据。
接下来，实现客户端队列代码：
import io.netty.channel.Channel;
import io.netty.channel.socket.SocketChannel;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class NettyChannelMap {
private static Map<String , SocketChannel> map = new ConcurrentHashMap<>();
public static void add(String clientId,SocketChannel channel){
map.put(clientId, channel);
}
public static Channel get(String clientId){
return map.get(clientId);
}
public static void remove(SocketChannel channel){
for (Map.Entry<String,SocketChannel> entry:map.entrySet()){
if (entry.getValue()==channel){
map.remove(entry.getKey());
}
}
}
}
服务端：
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import java.nio.charset.Charset;
public class NettyServer {
private int port;
public SocketChannel socketChannel;
public NettyServer(int port) throws InterruptedException {
this.port = port;
bind();
}
private void bind() throws InterruptedException {
EventLoopGroup boss=new NioEventLoopGroup();
EventLoopGroup worker=new NioEventLoopGroup();
ServerBootstrap bootstrap=new ServerBootstrap();
bootstrap.group(boss,worker);
bootstrap.channel(NioServerSocketChannel.class);
bootstrap.option(ChannelOption.SO_BACKLOG, 128);
//通过NoDelay禁用Nagle,使消息立即发出去，不用等待到一定的数据量才发出去
bootstrap.option(ChannelOption.TCP_NODELAY, true);
//保持长连接状态
bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true);
bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline p = socketChannel.pipeline();
//字符串类解析
//这里只能添加字符串的编码和解码器，
//网上有很多例子是这样写的：
//这种写法只能所有客户端都用netty写，否则其他框架实现的客户端无法发送消息到服务端,因为他是转换的netty自己的Object
//p.addLast(new ObjectEncoder());
//p.addLast(new ObjectDecoder(ClassResolvers.cacheDisabled(this.getClass().getClassLoader())));
p.addLast(new StringEncoder(Charset.forName("UTF-8")));
p.addLast(new StringDecoder(Charset.forName("UTF-8")));
p.addLast(new NettyServerHandler());
}
});
ChannelFuture f= bootstrap.bind(port).sync();
if(f.isSuccess()){
System.out.println("server start---------------");
}
}
public static void main(String []args) throws InterruptedException {
if(args.length == 0){
new NettyServer(9999);
}else{
new NettyServer(Integer.parseInt(args[0]));
}
}
}
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.SocketChannel;
import cn.sunsharp.netty.bean.Message;
import cn.sunsharp.netty.bean.MsgType;
import cn.sunsharp.netty.bean.NettyChannelMap;
import com.alibaba.fastjson.JSON;
//最好继承
SimpleChannelInboundHandler表示传递字符串消息，handler会把json格式的字符串转换为Message对象
public class NettyServerHandler extends SimpleChannelInboundHandler{@Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { //channel失效，从Map中移除 NettyChannelMap.remove((SocketChannel)ctx.channel()); }@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)throws Exception {//cause.printStackTrace();System.out.println(“出现异常！”);}@Overrideprotected void messageReceived(ChannelHandlerContext ctx, String msg)throws Exception {System.out.println(msg);Message message = JSON.parseObject(msg+”“, Message.class);System.out.println(“接收到消息：”+message);String clientId = message.getClientId();if(MsgType.LOGIN.equals(message.getType())){System.out.printf(“将%s添加到队列n”,clientId); NettyChannelMap.add(clientId,(SocketChannel)ctx.channel()); }else{ if(NettyChannelMap.get(clientId)==null){ System.out.printf(“登录失败，请重新登录!”,clientId); //说明未登录，或者连接断了，服务器向客户端发起登录请求，让客户端重新登录 message = new Message(MsgType.LOGIN); ctx.channel().writeAndFlush(JSON.toJSONString(message)); } } switch (message.getType()){ case PING:{ message = new Message(MsgType.PING); NettyChannelMap.get(clientId).writeAndFlush(JSON.toJSONString(message)); }break; case SEND:{ //收到客户端的请求，发送给targetId System.out.println(“发送消息：”+message); if(NettyChannelMap.get(message.getTargetId()) != null){ NettyChannelMap.get(message.getTargetId()).writeAndFlush(JSON.toJSONString(message)); }else{ message.setType(MsgType.NO_TARGET); NettyChannelMap.get(clientId).writeAndFlush(JSON.toJSONString(message)); } }break; default:break; }}}客户端可以使用任何框架任何语言的Socket来连接并发送消息，为了方便，这里依然用Netty来实现客户端：
import java.nio.charset.Charset;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import io.netty.util.concurrent.DefaultEventExecutorGroup;
import io.netty.util.concurrent.EventExecutorGroup;
import cn.sunsharp.regulation.bean.Message;
import cn.sunsharp.regulation.bean.MsgType;
import com.alibaba.fastjson.JSON;
public class NettyClient {
private int port;
private String host;
public SocketChannel socketChannel;
private static final EventExecutorGroup group = new DefaultEventExecutorGroup(20);
public NettyClient(int port, String host) {
this.port = port;
this.host = host;
start();
}
private void start(){
ChannelFuture future = null;
try {
EventLoopGroup eventLoopGroup=new NioEventLoopGroup();
Bootstrap bootstrap=new Bootstrap();
bootstrap.channel(NioSocketChannel.class);
bootstrap.option(ChannelOption.SO_KEEPALIVE,true);
bootstrap.group(eventLoopGroup);
bootstrap.remoteAddress(host,port);
bootstrap.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
socketChannel.pipeline().addLast(new IdleStateHandler(20,10,0));
socketChannel.pipeline().addLast(new StringEncoder(Charset.forName("UTF-8")));
socketChannel.pipeline().addLast(new StringDecoder(Charset.forName("UTF-8")));
socketChannel.pipeline().addLast(new NettyClientHandler());
}
});
future =bootstrap.connect(host,port).sync();
if (future.isSuccess()) {
socketChannel = (SocketChannel)future.channel();
System.out.println("connect server 成功---------");
}else{
System.out.println("连接失败！");
System.out.println("准备重连！");
start();
}
} catch (Exception e) {
}finally{
// if(null != future){
// if(null != future.channel() && future.channel().isOpen()){
// future.channel().close();
// }
// }
// System.out.println(“准备重连！”);
// start();
}
}
public static void main(String[]args) throws InterruptedException {
NettyClient bootstrap=new NettyClient(9999,”192.168.1.38”);
System.out.println(11111);
Message loginMsg=new Message(MsgType.LOGIN);
loginMsg.setClientId(“001”);
loginMsg.setTargetId(“192.168.1.38”);
loginMsg.setType(MsgType.LOGIN);
bootstrap.socketChannel.writeAndFlush(JSON.toJSON(loginMsg));
}
}
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.timeout.IdleStateEvent;
import cn.sunsharp.regulation.bean.Message;
import cn.sunsharp.regulation.bean.MsgType;
import com.alibaba.fastjson.JSON;
public class NettyClientHandler extends SimpleChannelInboundHandler {
public static ChannelHandlerContext context = null;
//利用写空闲发送心跳检测消息
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
if (evt instanceof IdleStateEvent) {
IdleStateEvent e = (IdleStateEvent) evt;
switch (e.state()) {
case WRITER_IDLE:
Message pingMsg=new Message(MsgType.PING);
ctx.writeAndFlush(JSON.toJSON(pingMsg));
System.out.println("send ping to server----------");
break;
default:
break;
}
}
}
@Override
protected void messageReceived(ChannelHandlerContext ctx, String msg)
throws Exception {
Message message = JSON.parseObject(msg+"", Message.class);
MsgType msgType=message.getType();
switch (msgType){
case LOGIN:{
//向服务器发起登录
message = new Message(MsgType.LOGIN);
ctx.writeAndFlush(JSON.toJSONString(message));
}break;
case PING:{
System.out.println("receive ping from server----------");
}break;
case SEND:{
//收到服务端消息
System.out.println("收到服务端消息："+message.getData());
}break;
case NO_TARGET:{
//收到服务端消息
System.out.println("找不到targetId:"+message.getTargetId());
}break;
default:break;
}
}
}
最后
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