Netty学习

以下两个例子基于netty-3.5.7.Final.jar用Junit进行测试

第一个例子：简单的发送字符串，接收字符串“Hello, World”

 class HelloWorldServerHandler extends SimpleChannelHandler {
      public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e)
              throws Exception {
         e.getChannel().write("Hello, World");
     }

      public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
         System.out.println("Unexpected exception from downstream."
                 + e.getCause());
         e.getChannel().close();
     }
 }

 class HelloWorldClientHandler extends SimpleChannelHandler {

      public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
         String message = (String) e.getMessage();
         System.out.println(message);
         e.getChannel().close();
     }

      public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
         System.out.println("Unexpected exception from downstream."
                 + e.getCause());
         e.getChannel().close();
     }
 }


 /**
 * Netty VS MinaNetty基于Pipeline处理，Mina基于Filter过滤
 * Netty的事件驱动模型具有更好的扩展性和易用性
 * Https，SSL，PB，RSTP，Text &Binary等协议支持
 * Netty中UDP传输有更好的支持官方测试Netty比Mina性能更好
 * @author Administrator
 *
 */
 public class TestCase {

      public void testServer() {
          //初始化channel的辅助类，为具体子类提供公共数据结构
         ServerBootstrap bootstrap =  new ServerBootstrap(
                  new NioServerSocketChannelFactory(
                         Executors.newCachedThreadPool(),
                         Executors.newCachedThreadPool()));
         bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
              public ChannelPipeline getPipeline() {
                 ChannelPipeline pipeline = Channels.pipeline();
                 pipeline.addLast("decoder", new StringDecoder());
                 pipeline.addLast("encoder", new StringEncoder());
                 pipeline.addLast("handler", new HelloWorldServerHandler());
                  return pipeline;
             }
         });
          //创建服务器端channel的辅助类,接收connection请求
         bootstrap.bind(new InetSocketAddress(8080));
     }



      public void testClient() {
          //创建客户端channel的辅助类,发起connection请求
         ClientBootstrap bootstrap =  new ClientBootstrap(
                  new NioClientSocketChannelFactory(
                         Executors.newCachedThreadPool(),
                         Executors.newCachedThreadPool()));
          //It means one same HelloWorldClientHandler instance is going to handle multiple Channels and consequently the data will be corrupted.
          //基于上面这个描述，必须用到ChannelPipelineFactory每次创建一个pipeline
         bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
              public ChannelPipeline getPipeline() {
                 ChannelPipeline pipeline =  Channels.pipeline();
                 pipeline.addLast("decoder", new StringDecoder());
                 pipeline.addLast("encoder", new StringEncoder());
                 pipeline.addLast("handler", new HelloWorldClientHandler());
                  return pipeline;
             }
         });
          //创建无连接传输channel的辅助类(UDP),包括client和server
         ChannelFuture future = bootstrap.connect(new InetSocketAddress(
                  "localhost", 8080));
         future.getChannel().getCloseFuture().awaitUninterruptibly();
         bootstrap.releaseExternalResources();
     }


     @Test
      public void testNetty(){
         testServer();
         testClient();
     }

 }

第二个例子，实际应用中会用到这个，发送POJO类Persons [name=周杰伦123, age=31, salary=10000.44]

 /**
 * 用POJO代替ChannelBuffer
 */

 class TimeServerHandler3 extends SimpleChannelHandler {

     @Override
      public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e)
              throws Exception {
         Persons person =  new Persons("周杰伦123",31,10000.44);
         ChannelFuture future = e.getChannel().write(person);
         future.addListener(ChannelFutureListener.CLOSE);
     }
 }

 class TimeClientHandler3 extends SimpleChannelHandler{

     @Override
      public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
              throws Exception {
         Persons person = (Persons)e.getMessage();
         System.out.println(person);
         e.getChannel().close();
     }
 }

 /**
 * FrameDecoder and ReplayingDecoder allow you to return an object of any type.
 *
 */
 class TimeDecoder extends FrameDecoder {
      private final ChannelBuffer buffer = dynamicBuffer();

     @Override
      protected Object decode(ChannelHandlerContext ctx, Channel channel,
             ChannelBuffer channelBuffer)  throws Exception {
          if(channelBuffer.readableBytes()<4) {
              return null;
         }
          if (channelBuffer.readable()) {
              // 读到,并写入buf
             channelBuffer.readBytes(buffer, channelBuffer.readableBytes());
         }
          int namelength = buffer.readInt();
         String name =  new String(buffer.readBytes(namelength).array(),"GBK");
          int age = buffer.readInt();
          double salary = buffer.readDouble();
         Persons person =  new Persons(name,age,salary);
          return person;
     }

 }

 class TimeEncoder extends SimpleChannelHandler {
      private final ChannelBuffer buffer = dynamicBuffer();

     @Override
      public void writeRequested(ChannelHandlerContext ctx, MessageEvent e)
              throws Exception {
         Persons person = (Persons)e.getMessage();
         buffer.writeInt(person.getName().getBytes("GBK").length);
         buffer.writeBytes(person.getName().getBytes("GBK"));
         buffer.writeInt(person.getAge());
         buffer.writeDouble(person.getSalary());
         Channels.write(ctx, e.getFuture(), buffer);
     }
 }

 class Persons{
      private String name;
      private int age;
      private double salary;

      public Persons(String name,int age,double salary){
          this.name = name;
          this.age = age;
          this.salary = salary;
     }

      public String getName() {
          return name;
     }
      public void setName(String name) {
          this.name = name;
     }
      public int getAge() {
          return age;
     }
      public void setAge(int age) {
          this.age = age;
     }
      public double getSalary() {
          return salary;
     }
      public void setSalary(double salary) {
          this.salary = salary;
     }

     @Override
      public String toString() {
          return "Persons [name=" + name + ", age=" + age +  ", salary=" + salary
                 +  "]";
     }


 }

 public class TestCase5 {
      public void testServer() {
           ChannelFactory factory =  new NioServerSocketChannelFactory(Executors.newCachedThreadPool(), Executors.newCachedThreadPool());
             ServerBootstrap bootstrap =  new ServerBootstrap(factory);
             bootstrap.setPipelineFactory(new ChannelPipelineFactory() {

                  public ChannelPipeline getPipeline()  throws Exception {
                      return Channels.pipeline(new TimeEncoder(), new TimeServerHandler3());
                 }
             });
             bootstrap.setOption("child.tcpNoDelay", true);
             bootstrap.setOption("child.keepAlive", true);

             bootstrap.bind(new InetSocketAddress("localhost",9999));
     }

      public void testClient(){
          //创建客户端channel的辅助类,发起connection请求
         ClientBootstrap bootstrap =  new ClientBootstrap(
                  new NioClientSocketChannelFactory(
                         Executors.newCachedThreadPool(),
                         Executors.newCachedThreadPool()));
         bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
              public ChannelPipeline getPipeline() {
                 ChannelPipeline pipeline =  Channels.pipeline();
                 pipeline.addLast("decoder", new TimeDecoder());
                 pipeline.addLast("encoder", new TimeEncoder());
                 pipeline.addLast("handler", new TimeClientHandler3());
                  return pipeline;
             }
         });
          //创建无连接传输channel的辅助类(UDP),包括client和server
         ChannelFuture future = bootstrap.connect(new InetSocketAddress(
                  "localhost", 9999));
         future.getChannel().getCloseFuture().awaitUninterruptibly();
         bootstrap.releaseExternalResources();
     }

     @Test
      public void testNetty() {
             testServer();
             testClient();
     }
 }

这两段代码是学习的时候参考别人的代码，转于哪想不起来了，但是这两段代码让我了解了netty的通信流程。