Question

这种方法来自EchoClientHandler会覆盖什么？

@Override
public void channelActive(ChannelHandlerContext ctx) {
    ctx.writeAndFlush(firstMessage);
}

编译错误：

-do-compile:
    [mkdir] Created dir: /home/thufir/NetBeansProjects/NettyEcho/build/empty
    [mkdir] Created dir: /home/thufir/NetBeansProjects/NettyEcho/build/generated-sources/ap-source-output
    [javac] Compiling 4 source files to /home/thufir/NetBeansProjects/NettyEcho/build/classes
    [javac] /home/thufir/NetBeansProjects/NettyEcho/src/io/netty/example/echo/EchoClientHandler.java:27: error: method does not override or implement a method from a supertype
    [javac]     @Override
    [javac]     ^

来自github的代码：

package io.netty.example.echo;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

/**
* Handler implementation for the echo client. It initiates the ping-pong
* traffic between the echo client and server by sending the first message to
* the server.
*/
public class EchoClientHandler extends ChannelHandlerAdapter {

    private final ByteBuf firstMessage;

    /**
* Creates a client-side handler.
*/
    public EchoClientHandler() {
        firstMessage = Unpooled.buffer(EchoClient.SIZE);
        for (int i = 0; i < firstMessage.capacity(); i ++) {
            firstMessage.writeByte((byte) i);
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(firstMessage);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ctx.write(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
       ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        // Close the connection when an exception is raised.
        cause.printStackTrace();
        ctx.close();
    }
}

当我查看ChannelHandlerAdapter时，我看不到这些方法......

Answer 1

你正在混淆版本。

在Netty 4中，你有EchoClientHandler：

public class  EchoClientHandler extends ChannelInboundHandlerAdapter

在Netty 4中，ChannelInboundHandlerAdapter有channelActive方法。

您的链接适用于Netty 5中的EchoClientHandler，其中ChannelHandlerAdapter已更新，并且有更多方法，包括channelActive。

扩展ChannelHandlerAdapter，但不会覆盖或实现ChannelHandlerAdapter中的方法

1 个答案: