netty 代理服务器

Netty 是一个高性能、异步事件驱动的网络应用程序框架，提供了一种简单、快速的方式来开发网络应用程序。Netty 可以被用于开发各种类型的网络应用程序，其中包括代理服务器。代理服务器是一种中间服务器，它可以代表客户端向目标服务器发送请求，同时也可以将来自目标服务器的响应返回给客户端。使用 Netty 可以快速地开发高性能的代理服务器，具体实现可以参考 Netty 的官方文档和示例代码。

相关问题

netty 实现代理服务器

Netty是一款基于NIO的网络编程框架，提供了高效、稳定、灵活的网络编程能力。使用Netty实现代理服务器可以简化开发过程，提高性能和可维护性。

以下是使用Netty实现代理服务器的示例代码：

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.*;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.*;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.stream.ChunkedWriteHandler;

public class ProxyServer {
    public static void main(String[] args) throws Exception {
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(workerGroup)
                    .channel(NioSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .option(ChannelOption.AUTO_READ, false)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new HttpClientCodec());
                            ch.pipeline().addLast(new HttpObjectAggregator(65536));
                            ch.pipeline().addLast(new ChunkedWriteHandler());
                            ch.pipeline().addLast(new ProxyServerHandler());
                        }
                    });

            ChannelFuture future = bootstrap.connect("www.example.com", 80).sync();
            future.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
        }
    }

    private static class ProxyServerHandler extends ChannelInboundHandlerAdapter {
        private Channel remoteChannel;

        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            remoteChannel = ctx.channel();
            ctx.read();
        }

        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            if (msg instanceof HttpRequest) {
                HttpRequest request = (HttpRequest) msg;
                String host = request.headers().get("Host");
                ChannelFuture future = new Bootstrap()
                        .group(ctx.channel().eventLoop())
                        .channel(ctx.channel().getClass())
                        .handler(new LoggingHandler(LogLevel.INFO))
                        .option(ChannelOption.AUTO_READ, false)
                        .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 10000)
                        .handler(new ChannelInitializer<SocketChannel>() {
                            @Override
                            protected void initChannel(SocketChannel ch) throws Exception {
                                ch.pipeline().addLast(new HttpResponseDecoder());
                                ch.pipeline().addLast(new HttpObjectAggregator(65536));
                                ch.pipeline().addLast(new ChunkedWriteHandler());
                                ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {
                                    @Override
                                    public void channelActive(ChannelHandlerContext ctx) throws Exception {
                                        ctx.writeAndFlush(request);
                                        ctx.read();
                                    }

                                    @Override
                                    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
                                        if (msg instanceof HttpResponse) {
                                            HttpResponse response = (HttpResponse) msg;
                                            response.headers().remove("Transfer-Encoding");
                                            response.headers().remove("Content-Length");
                                            remoteChannel.writeAndFlush(response);
                                            remoteChannel.writeAndFlush(new ChunkedNioStream((ByteBuf) msg));
                                        } else if (msg instanceof HttpContent) {
                                            remoteChannel.writeAndFlush(new ChunkedNioStream((ByteBuf) msg));
                                            if (msg instanceof LastHttpContent) {
                                                remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                                                        .addListener(ChannelFutureListener.CLOSE);
                                            }
                                        }
                                    }

                                    @Override
                                    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
                                        remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                                                .addListener(ChannelFutureListener.CLOSE);
                                    }

                                    @Override
                                    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
                                        cause.printStackTrace();
                                        remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                                                .addListener(ChannelFutureListener.CLOSE);
                                    }
                                });
                            }
                        })
                        .connect(host, 80);
                remoteChannel.config().setAutoRead(false);
                future.addListener((ChannelFutureListener) future1 -> {
                    if (future1.isSuccess()) {
                        remoteChannel.config().setAutoRead(true);
                        ctx.channel().config().setAutoRead(true);
                    } else {
                        remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                                .addListener(ChannelFutureListener.CLOSE);
                        ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                                .addListener(ChannelFutureListener.CLOSE);
                    }
                });
            } else if (msg instanceof HttpContent) {
                remoteChannel.writeAndFlush(new ChunkedNioStream((ByteBuf) msg));
                if (msg instanceof LastHttpContent) {
                    remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
                }
            }
        }

        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            if (remoteChannel != null) {
                remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                        .addListener(ChannelFutureListener.CLOSE);
            }
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            cause.printStackTrace();
            if (remoteChannel != null) {
                remoteChannel.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT)
                        .addListener(ChannelFutureListener.CLOSE);
            }
            ctx.close();
        }
    }
}

以上代码中，代理服务器连接到目标服务器的IP地址和端口号是硬编码的，你需要根据实际情况进行修改。在启动代理服务器之后，当客户端发送HTTP请求时，会在一个新的线程中处理请求，解析请求并连接到目标服务器，将请求转发给目标服务器。接收到目标服务器的响应后，将响应转发给客户端。

JAVA使用netty生成代理

在Java中使用Netty生成代理需要使用动态代理技术。下面是一个简单的示例代码，演示了如何使用Netty生成代理：

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
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 java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

interface MyService {
    String hello(String name);
}

class MyServiceHandler extends ChannelInboundHandlerAdapter {
    private Object result;

    public Object getResult() {
        return result;
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        result = msg;
        ctx.close();
    }
}

class MyServiceProxy implements InvocationHandler {
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            MyServiceHandler handler = new MyServiceHandler();
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group)
                    .channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(handler);
                        }
                    });
            Channel channel = bootstrap.connect("localhost", 8888).sync().channel();
            channel.writeAndFlush(args[0]);
            channel.closeFuture().sync();

            return handler.getResult();
        } finally {
            group.shutdownGracefully();
        }
    }
}

public class NettyProxyExample {
    public static void main(String[] args) {
        MyService myService = (MyService) Proxy.newProxyInstance(
                NettyProxyExample.class.getClassLoader(),
                new Class[]{MyService.class},
                new MyServiceProxy()
        );

        String result = myService.hello("World");
        System.out.println(result);
    }
}

以上示例代码中，定义了一个`MyService`接口，代表需要代理的服务。`MyServiceHandler`是Netty的`ChannelInboundHandlerAdapter`的子类，用于处理接收到的响应消息，并将结果存储在`result`变量中。`MyServiceProxy`是动态代理的实现类，它通过Netty客户端与服务器进行通信，并将代理方法的参数发送给服务器，然后等待服务器返回结果。

在`NettyProxyExample`的`main`方法中，使用`Proxy.newProxyInstance`方法创建了一个代理对象，该代理对象实现了`MyService`接口，并使用`MyServiceProxy`作为其调用处理器。通过代理对象调用接口方法时，实际上是调用了`MyServiceProxy`的`invoke`方法，在该方法内部使用Netty进行远程调用并获取结果。

请注意，以上示例仅仅是一个简单的示例，实际应用中可能需要根据具体需求进行适当修改和扩展。