一、类介绍
1.ChannelPool——连接池接口

2.SimpleChannelPool——实现ChannelPool接口，简单的连接池实现

3.FixedChannelPool——继承SimpleChannelPool，有大小限制的连接池实现

4.ChannelPoolMap——管理host与连接池映射的接口

5.AbstractChannelPoolMap——抽象类，实现ChannelPoolMap接口

二、具体使用
a、MyNettyPool——Netty自带连接池的用法

package com.dxfx.netty.demo; import com.alibaba.fastjson.JSONObject; import com.dxfx.netty.framework.Constants; import com.dxfx.netty.framework.DefaultFuture; import com.dxfx.netty.framework.NettyClientHandler; import com.dxfx.netty.param.RequestParam; import com.dxfx.netty.param.Response; import io.netty.bootstrap.Bootstrap; import io.netty.channel.Channel; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.pool.AbstractChannelPoolMap; import io.netty.channel.pool.ChannelPoolHandler; import io.netty.channel.pool.ChannelPoolMap; import io.netty.channel.pool.FixedChannelPool; import io.netty.channel.socket.nio.NioSocketChannel; import io.netty.handler.codec.DelimiterBasedFrameDecoder; import io.netty.handler.codec.Delimiters; import io.netty.handler.codec.string.StringDecoder; import io.netty.handler.codec.string.StringEncoder; import io.netty.util.concurrent.Future; import io.netty.util.concurrent.FutureListener; /** * Netty自带连接池的用法 * * @author Administrator * */public class MyNettyPool { // key为目标host，value为目标host的连接池 public static ChannelPoolMap<String, FixedChannelPool> poolMap; private static final Bootstrap bootstrap = new Bootstrap(); static { bootstrap.group(new NioEventLoopGroup()); bootstrap.channel(NioSocketChannel.class); bootstrap.remoteAddress("localhost", 8080); } public MyNettyPool() { init(); } /** * netty连接池使用 * */ public void init() { poolMap = new AbstractChannelPoolMap<String, FixedChannelPool>() { @Override protected FixedChannelPool newPool(String key) { ChannelPoolHandler handler = new ChannelPoolHandler() { /** * 使用完channel需要释放才能放入连接池 * */ @Override public void channelReleased(Channel ch) throws Exception { // 刷新管道里的数据 // ch.writeAndFlush(Unpooled.EMPTY_BUFFER); // flush掉所有写回的数据  System.out.println("channelReleased......"); } /** * 当链接创建的时候添加channelhandler，只有当channel不足时会创建，但不会超过限制的最大channel数 * */ @Override public void channelCreated(Channel ch) throws Exception { ch.pipeline().addLast(new StringEncoder()); ch.pipeline().addLast(new DelimiterBasedFrameDecoder(Integer.MAX_VALUE, Delimiters.lineDelimiter()[0])); ch.pipeline().addLast(new StringDecoder()); // 绑定channel的handler ch.pipeline().addLast(new NettyClientHandler()); } /** * 获取连接池中的channel * */ @Override public void channelAcquired(Channel ch) throws Exception { System.out.println("channelAcquired......"); } }; return new FixedChannelPool(bootstrap, handler, 50); //单个host连接池大小 } }; } /** * 发送请求 * * @param msg * 请求参数 * @param command * 请求方法 * @return */ public Response send(final Object msg, final String command) { //封装请求数据 final RequestParam request = new RequestParam(); request.setCommand(command); request.setContent(msg); //从连接池中获取连接 final FixedChannelPool pool = poolMap.get("localhost"); //申请连接，没有申请到或者网络断开，返回null Future<Channel> future = pool.acquire(); future.addListener(new FutureListener<Channel>() { @Override public void operationComplete(Future<Channel> future) throws Exception { //给服务端发送数据 Channel channel = future.getNow(); channel.write(JSONObject.toJSONString(request)); channel.writeAndFlush(Constants.DELIMITER); System.out.println(channel.id()); // 连接放回连接池，这里一定记得放回去 pool.release(channel); } }); //获取服务端返回的数据 DefaultFuture defaultFuture = new DefaultFuture(request); return defaultFuture.get(); } }

b、MyNettyPoolTest——Netty自带连接池测试类，SpringServer为连接池启动类

package com.dxfx.netty.demo; import com.dxfx.netty.param.Response; import com.dxfx.user.model.User; /** * Netty自带连接池测试类，SpringServer为连接池启动类 * * @author Administrator * */public class MyNettyPoolTest { public static void main(String[] args) { User user = new User(); user.setAge(12); user.setId(23); user.setName("client"); String command = "login"; MyNettyPool pool = new MyNettyPool(); new MyThread(pool, user, command).start(); new MyThread(pool, user, command).start(); new MyThread(pool, user, command).start(); new MyThread(pool, user, command).start(); for (int i = 0; i < 50000; i++) { new MyThread(pool, user, command).start(); } } } class MyThread extends Thread { public MyNettyPool pool; public Object msg; public String command; public MyThread(MyNettyPool pool, Object msg, String command) { super(); this.pool = pool; this.msg = msg; this.command = command; } @Override public void run() { Response response = pool.send(msg, command); //System.out.println(response); } }