写在前面
本文看下如何使用redis来实现一个类似于redis官方提供的redis-cli.exe的客户端工具。
1：用到的模块
主要需要用到netty针对redis的编解码模块，可以解析redis的协议，从而可以实现和redis交互的功能。
2：正文
首先来定义客户端类：
package com.dahuyou.netty.redis.cli;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.util.concurrent.GenericFutureListener;
import javax.swing.plaf.synth.SynthRadioButtonMenuItemUI;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class RedisClient {
String host; // 目标主机
int port; // 目标主机端口
public RedisClient(String host,int port){
this.host = host;
this.port = port;
}
public void start() throws Exception{
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group)
.channel(NioSocketChannel.class)
.handler(new RedisClientInitializer());
Channel channel = bootstrap.connect(host, port).sync().channel();
System.out.println(" connected to host : " + host + ", port : " + port);
System.out.println(" type redis's command to communicate with redis-server or type 'quit' to shutdown ");
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
ChannelFuture lastWriteFuture = null;
for (;;) {
Thread.sleep(1000);
RedisClientHandler.serialNum = 0;
System.out.println(host + ":" + port + ">");
String s = in.readLine();
if(s.equalsIgnoreCase("quit")) {
break;
}
// System.out.print(">");
lastWriteFuture = channel.writeAndFlush(s);
lastWriteFuture.addListener(new GenericFutureListener<ChannelFuture>() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (!future.isSuccess()) {
System.err.print("write failed: ");
future.cause().printStackTrace(System.err);
}
}
});
}
if (lastWriteFuture != null) {
lastWriteFuture.sync();
}
System.out.println(" bye ");
}finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception{
// RedisClient client = new RedisClient("192.168.56.10",6379);
RedisClient client = new RedisClient("127.0.0.1",6379);
client.start();
}
}
这里redis server其实就是一个tcp server的角色了。
在启动类中同一个for (;;) {的死循环来等待用户录入信息，类似于redis-cli.exe的如下功能：
另外，通过RedisClientInitializer设置协议解析的编解码器，如下：
package com.dahuyou.netty.redis.cli;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.redis.RedisArrayAggregator;
import io.netty.handler.codec.redis.RedisBulkStringAggregator;
import io.netty.handler.codec.redis.RedisDecoder;
import io.netty.handler.codec.redis.RedisEncoder;
public class RedisClientInitializer extends ChannelInitializer<Channel> {
@Override
protected void initChannel(Channel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new RedisDecoder());
pipeline.addLast(new RedisBulkStringAggregator());
pipeline.addLast(new RedisArrayAggregator());
pipeline.addLast(new RedisEncoder());
pipeline.addLast(new RedisClientHandler());
}
}
RedisDecoder，RedisBulkStringAggregator，RedisArrayAggregator，RedisEncoder这几个类都是redis codec模块提供的编解码类，如下：
RedisClientHandler是我们自定义的业务处理类，源码如下：
package com.dahuyou.netty.redis.cli;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.handler.codec.CodecException;
import io.netty.handler.codec.redis.*;
import io.netty.util.CharsetUtil;
import io.netty.util.ReferenceCountUtil;
import java.util.ArrayList;
import java.util.List;
public class RedisClientHandler extends ChannelDuplexHandler {
// 发送 redis 命令
@Override
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
String[] commands = ((String) msg).split("\\s+");
List<RedisMessage> children = new ArrayList<>(commands.length);
for (String cmdString : commands) {
children.add(new FullBulkStringRedisMessage(ByteBufUtil.writeUtf8(ctx.alloc(), cmdString)));
}
RedisMessage request = new ArrayRedisMessage(children);
ctx.write(request, promise);
}
// 接收 redis 响应数据
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
RedisMessage redisMessage = (RedisMessage) msg;
// 打印响应消息
printAggregatedRedisResponse(redisMessage);
// 是否资源
ReferenceCountUtil.release(redisMessage);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
System.err.print("exceptionCaught: ");
cause.printStackTrace(System.err);
ctx.close();
}
private static void printAggregatedRedisResponse(RedisMessage msg) {
if (msg instanceof SimpleStringRedisMessage) {
System.out.println(((SimpleStringRedisMessage) msg).content());
} else if (msg instanceof ErrorRedisMessage) {
System.out.println(((ErrorRedisMessage) msg).content());
} else if (msg instanceof IntegerRedisMessage) {
System.out.println(((IntegerRedisMessage) msg).value());
} else if (msg instanceof FullBulkStringRedisMessage) {
System.out.println(getString((FullBulkStringRedisMessage) msg));
} else if (msg instanceof ArrayRedisMessage) {
for (RedisMessage child : ((ArrayRedisMessage) msg).children()) {
printAggregatedRedisResponse(child);
}
} else {
throw new CodecException("unknown message type: " + msg);
}
}
public static int serialNum = 0;
private static String getString(FullBulkStringRedisMessage msg) {
if (msg.isNull()) {
return "(null)";
}
return ++serialNum + ") " +msg.content().toString(CharsetUtil.UTF_8);
}
}
运行测试：
写在后面
参考文章列表
redis的基本命令，并用netty操作redis（不使用springboot或者spring框架）就单纯的用netty搞。 。