netty的个人使用心得
Netty是由JBOSS提供的一个java开源框架。Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。
如果需要客户端和服务器端沟通 分别都需要编写一个 实现了SimpleChannelHandler接口的类，其中类中需要重写的主要方法为
channelConnected() and channelOpen() 这两个方法为 当客户端链接到服务器端得时候和 客户端 channel被创建出来的时候所调用的
channelDisconnected and channelClosed() 对应上面的两个方法
exceptionCaught 可以获得 对应handler端（服务器或客户端）的异常信息
messageReceived 每个 客户端 发送的信息后 将调用此方法
当编写完某端得程序后（客户端或服务器端） 将编写好的handler需要配置在 实现了ChannelPipelineFactory的类里,ChannelPipelineFactory中有一个需要实现的方法getPipeline将写好的handler配置到其中,在这个 工厂里 可能要添加很多东西
比如说 编解码器，心跳等。。。。
如需要自定义编解码器需要继承：LengthFieldBasedFrameDecoder（解码），OneToOneEncoder（编码）
编解码器(encode,decode)
encode为 调用messageReceived 方法之后调用的方法，则decode方法为 messageReceived 之前调用的方法 ，用于处理自定义包协议的解析于编辑
心跳： 当客户端socket在非正常情况家掉线，如： 断网，断电等特殊问题的时候， 客户端的channel对象不会自动关闭，需要一直接收到客户端的消息，从而判断是否可以和对象构成通信。。 如果 发现客户端空闲时间过长则视为掉线
服务端handler代码如下
package com.djyou.server;
import java.util.logging.Logger;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ChildChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.group.DefaultChannelGroup;
public class ChatServerHandler extends SimpleChannelHandler{
public static final ChannelGroup channelGroup = new DefaultChannelGroup();
public int id;
@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e)
throws Exception {
System.out.println("进来一个");
}
@Override
public void channelDisconnected(ChannelHandlerContext ctx,
ChannelStateEvent e) throws Exception {
super.channelDisconnected(ctx, e);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
throws Exception {
Logger.getAnonymousLogger().info(e.getCause().getMessage());
ctx.getChannel().close();
// TODO Auto-generated method stub
//super.exceptionCaught(ctx, e);
}
@Override
public void childChannelClosed(ChannelHandlerContext ctx,
ChildChannelStateEvent e) throws Exception {
super.childChannelClosed(ctx, e);
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
throws Exception {
System.out.println(this.id++);
//google protocol解码后返回为 ChannelBuffer类型
if(!(e.getMessage() instanceof ChannelBuffer)) return;
//获得 消息对象
ChannelBuffer channelBuffer = (ChannelBuffer)e.getMessage();
//MessageInfo info = Message.MessageInfo.newBuilder().mergeFrom(channelBuffer.copy().array()).build();
//写回给客户端
e.getChannel().write(channelBuffer);
}
}
pieplelineFactory里的代码为
package com.djyou.server;
import static org.jboss.netty.channel.Channels.*;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.handler.codec.protobuf.ProtobufVarint32FrameDecoder;
import org.jboss.netty.handler.codec.protobuf.ProtobufVarint32LengthFieldPrepender;
import org.jboss.netty.handler.timeout.IdleStateHandler;
import org.jboss.netty.util.Timer;
public class ChatPipelineServerFactory implements ChannelPipelineFactory{
private Timer timer;
public ChatPipelineServerFactory(Timer timer){
this.timer = timer;
}
@Override
public ChannelPipeline getPipeline() throws Exception {
ChannelPipeline pipeline = pipeline();
//添加netty默认支持的 编解码器(可自动添加包头，并处理粘包问题)
pipeline.addLast("frameDecoder", new ProtobufVarint32FrameDecoder());//对应
pipeline.addLast("frameEncoder", new ProtobufVarint32LengthFieldPrepender());//此对象为 netty默认支持protocolbuf的编解码器
pipeline.addLast("timeout", new IdleStateHandler(timer, 10, 10, 0));//此两项为添加心跳机制 10秒查看一次在线的客户端channel是否空闲，IdleStateHandler为netty jar包中提供的类
pipeline.addLast("hearbeat", new Heartbeat());//此类 实现了IdleStateAwareChannelHandler接口
//netty会定时扫描 空闲的channel
//pipeline.addLast("frameDecoder", new ProtobufDecoder(Message.MessageInfo.getDefaultInstance()));
//pipeline.addLast("frameEncoder", new ProtobufEncoder());//
pipeline.addLast("handler", new ChatServerHandler());//将编写好的服务器端的handler添加到这里
return pipeline;
}
}
心跳包的代码如下
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.timeout.IdleState;
import org.jboss.netty.handler.timeout.IdleStateAwareChannelHandler;
import org.jboss.netty.handler.timeout.IdleStateEvent;
public class Heartbeat extends IdleStateAwareChannelHandler{
int i = 0;
@Override
public void channelIdle(ChannelHandlerContext ctx, IdleStateEvent e)
throws Exception {
// TODO Auto-generated method stub
super.channelIdle(ctx, e);
if(e.getState() == IdleState.WRITER_IDLE)
i++;
if(i==3){
e.getChannel().close();
System.out.println("掉了。");
}
}
}
自定义解码器代码
package com.djyou.server;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
public class Decode extends LengthFieldBasedFrameDecoder{
public Decode(int maxFrameLength, int lengthFieldOffset,
int lengthFieldLength) {
super(maxFrameLength, lengthFieldOffset, lengthFieldLength);
// TODO Auto-generated constructor stub
}
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel,
ChannelBuffer buffer) throws Exception {
ChannelBuffer buffs = (ChannelBuffer)super.decode(ctx, channel, buffer);
return buffs;
}
}
自定义编码器代码
package com.djyou.server;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
public class Encode extends OneToOneEncoder{
@Override
protected Object encode(ChannelHandlerContext ctx, Channel channel,
Object msg) throws Exception {
// TODO Auto-generated method stub
return null;
}
}
服务端启动代码
package com.djyou.server;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelFactory;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.util.HashedWheelTimer;
import org.jboss.netty.util.Timer;
public class ChatServer {
public static void main(String[] args) {
ChannelFactory factory = new NioServerSocketChannelFactory(Executors
.newCachedThreadPool(), Executors.newCachedThreadPool(),
Runtime.getRuntime().availableProcessors() + 1);
Timer timer = new HashedWheelTimer();
ServerBootstrap bootstrap = new ServerBootstrap(factory);
bootstrap.setPipelineFactory(new ChatPipelineServerFactory(timer));
bootstrap.setOption("child.tcpNoDelay", true);
bootstrap.setOption("child.keepAlive", true);
bootstrap.setOption("reuseAddress", true);
bootstrap.bind(new InetSocketAddress(6666));
}
}
客户端启动代码如下（除客户端启动代码意外 其余的东西都与服务器端一样 都需要编写对应的 编解码器，定时发送消息线程（10秒发个信息给服务端 确保channel不为空闲， 来对应心跳程序）， 客户端的handler）
package com.djyou.client;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFactory;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
import com.djyou.protoBufModel.Message;
import com.djyou.protoBufModel.Message.MessageInfo;
public class ChatClient {
public static void main(String[] args) throws Exception{
String host = "localhost";
int port = 6666;
// Configure the client.
ChannelFactory factory =
new NioClientSocketChannelFactory(
Executors.newCachedThreadPool(),
Executors.newCachedThreadPool());
ClientBootstrap bootstrap = new ClientBootstrap(factory);
ChatPipelineClientFactory cpcf = new ChatPipelineClientFactory();
bootstrap.setPipelineFactory(cpcf);
// Start the connection attempt.
ChannelFuture future = bootstrap.connect(new InetSocketAddress(host, port));
// Wait until the connection attempt succeeds or fails.
Channel channel = future.awaitUninterruptibly().getChannel();
if (!future.isSuccess()) {
future.getCause().printStackTrace();
System.exit(0);
}
// Read commands from the stdin.
ChannelFuture lastWriteFuture = null;
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
// for (;;) {
// String line = in.readLine();
// if (line == null) {
// break;
// }
//创建Builder
MessageInfo.Builder builder = MessageInfo.newBuilder();
builder.addBody(Message.Body.newBuilder().setKey("message").setValue("你在干什么？" + "/n").build());
//创建 赋值结束的 Build 并生成 MessageInfo对象
MessageInfo messageInfo = builder.build();
//将messageInfo转换为字节
byte[] messageByte = messageInfo.toByteArray();
//获得此对象的长度
ChannelBuffer channelBuffer = ChannelBuffers.buffer(messageByte.length);
//将 获得到的数组写入 channelBuffer中
channelBuffer.writeBytes(messageByte);
//发送到服务器端
for(int i = 0; i < 10;i++){
lastWriteFuture = channel.write(channelBuffer);
}
if (lastWriteFuture != null) {
lastWriteFuture.awaitUninterruptibly();
}
// }
// Thread.sleep(50000);
// Wait until all messages are flushed before closing the channel.
Thread.sleep(50000);
// Close the connection. Make sure the close operation ends because
// all I/O operations are asynchronous in Netty.
channel.close().awaitUninterruptibly();
// We should shut down all thread pools here to exit normally.
// However, it is just fine to call System.exit(0) because we are
// finished with the business.
System.exit(0);
}
}