Netty学习（2）——Netty使用实例

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。