开始 Netty 入门示例

lab-67/lab-67-netty-demo/lab-67-netty-demo-client/pom.xml

@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>lab-67-netty-demo</artifactId>
+        <groupId>cn.iocoder.springboot.labs</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>lab-67-netty-demo-client</artifactId>
+
+    <properties>
+        <!-- 依赖相关配置 -->
+        <spring.boot.version>2.2.4.RELEASE</spring.boot.version>
+        <!-- 插件相关配置 -->
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
+    </properties>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-starter-parent</artifactId>
+                <version>${spring.boot.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <!-- 实现对 Spring MVC 的自动化配置 -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <!-- Netty 依赖 -->
+        <dependency>
+            <groupId>io.netty</groupId>
+            <artifactId>netty-all</artifactId>
+            <version>4.1.50.Final</version>
+        </dependency>
+
+        <!-- 引入 netty-demo-common 封装 -->
+        <dependency>
+            <groupId>cn.iocoder.springboot.labs</groupId>
+            <artifactId>lab-67-netty-demo-common</artifactId>
+            <version>1.0-SNAPSHOT</version>
+        </dependency>
+    </dependencies>
+
+</project>

lab-67/lab-67-netty-demo/lab-67-netty-demo-client/src/main/java/cn/iocoder/springboot/lab67/nettyclientdemo/NettyClientApplication.java

@@ -0,0 +1,4 @@
+package cn.iocoder.springboot.lab67.nettyclientdemo;
+
+public class NettyClientApplication {
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-client/src/main/java/cn/iocoder/springboot/lab67/nettyclientdemo/config/NettyClientConfig.java

@@ -0,0 +1,21 @@
+package cn.iocoder.springboot.lab67.nettyclientdemo.config;
+
+import cn.iocoder.springboot.lab67.nettycommondemo.dispacher.MessageDispatcher;
+import cn.iocoder.springboot.lab67.nettycommondemo.dispacher.MessageHandlerContainer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class NettyClientConfig {
+
+    @Bean
+    public MessageDispatcher messageDispatcher() {
+        return new MessageDispatcher();
+    }
+
+    @Bean
+    public MessageHandlerContainer messageHandlerContainer() {
+        return new MessageHandlerContainer();
+    }
+
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/pom.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>lab-67-netty-demo</artifactId>
+        <groupId>cn.iocoder.springboot.labs</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>lab-67-netty-demo-common</artifactId>
+
+    <properties>
+        <!-- 插件相关配置 -->
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
+    </properties>
+
+    <dependencies>
+        <!-- Netty 依赖 -->
+        <dependency>
+            <groupId>io.netty</groupId>
+            <artifactId>netty-all</artifactId>
+            <version>4.1.50.Final</version>
+        </dependency>
+
+        <!-- FastJSON 依赖 -->
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>fastjson</artifactId>
+            <version>1.2.71</version>
+        </dependency>
+
+        <!-- 引入 Spring 相关依赖 -->
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-aop</artifactId>
+            <version>5.2.5.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <version>5.2.5.RELEASE</version>
+        </dependency>
+
+        <!-- 引入 SLF4J 依赖 -->
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.30</version>
+        </dependency>
+    </dependencies>
+
+</project>

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/codec/Invocation.java

@@ -0,0 +1,41 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.codec;
+
+public class Invocation {
+
+    /**
+     * 类型 - 心跳请求
+     */
+    public static final String TYPE_HEARTBEAT_REQUEST = "HEARTBEAT_REQUEST";
+    /**
+     * 类型 - 心跳响应
+     */
+    public static final String TYPE_HEARTBEAT_RESPONSE = "HEARTBEAT_RESPONSE";
+
+    /**
+     * 类型
+     */
+    private String type;
+    /**
+     * 消息
+     */
+    private String message;
+
+    public String getType() {
+        return type;
+    }
+
+    public Invocation setType(String type) {
+        this.type = type;
+        return this;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public Invocation setMessage(String message) {
+        this.message = message;
+        return this;
+    }
+
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/codec/InvocationDecoder.java

@@ -0,0 +1,39 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.codec;
+
+import com.alibaba.fastjson.JSON;
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.ByteToMessageDecoder;
+import io.netty.handler.codec.CorruptedFrameException;
+
+import java.util.List;
+
+public class InvocationDecoder extends ByteToMessageDecoder {
+
+    @Override
+    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
+        // 标记当前读取位置
+        in.markReaderIndex();
+        // 判断是否能够读取 length 长度
+        if (in.readableBytes() <= 4) {
+            return;
+        }
+        // 读取长度
+        int length = in.readInt();
+        if (length < 0) {
+            throw new CorruptedFrameException("negative length: " + length);
+        }
+        // 如果 message 不够可读，则退回到原读取位置
+        if (in.readableBytes() < length) {
+            in.resetReaderIndex();
+            return;
+        }
+        // 读取内容
+        ByteBuf byteBuf = in.readRetainedSlice(length);
+        // 解析成 Invocation
+        byte[] content = byteBuf.array();
+        Invocation invocation = JSON.parseObject(content, Invocation.class);
+        out.add(invocation);
+    }
+
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/codec/InvocationEncoder.java

@@ -0,0 +1,20 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.codec;
+
+import com.alibaba.fastjson.JSON;
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.MessageToByteEncoder;
+
+public class InvocationEncoder extends MessageToByteEncoder<Invocation> {
+
+    @Override
+    protected void encode(ChannelHandlerContext ctx, Invocation invocation, ByteBuf out) {
+        // 将 Invocation 转换成 byte[] 数组
+        byte[] content = JSON.toJSONBytes(invocation);
+        // 写入 length
+        out.writeInt(content.length);
+        // 写入内容
+        out.writeBytes(content);
+    }
+
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/dispacher/Message.java

@@ -0,0 +1,4 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.dispacher;
+
+public interface Message {
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/dispacher/MessageDispatcher.java

@@ -0,0 +1,28 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.dispacher;
+
+import cn.iocoder.springboot.lab67.nettycommondemo.codec.Invocation;
+import com.alibaba.fastjson.JSON;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.SimpleChannelInboundHandler;
+import org.springframework.beans.factory.annotation.Autowired;
+
+@ChannelHandler.Sharable
+public class MessageDispatcher extends SimpleChannelInboundHandler<Invocation> {
+
+    @Autowired
+    private MessageHandlerContainer messageHandlerContainer;
+
+    @Override
+    protected void channelRead0(ChannelHandlerContext ctx, Invocation invocation) {
+        // 获得 type 对应的 MessageHandler 处理器
+        MessageHandler messageHandler = messageHandlerContainer.getMessageHandler(invocation.getType());
+        // 解析消息
+        Class<? extends Message> messageClass = MessageHandlerContainer.getMessageClass(messageHandler);
+        Message message = JSON.parseObject(invocation.getMessage(), messageClass);
+        // 执行逻辑
+        // noinspection unchecked
+        messageHandler.execute(ctx.channel(), message);
+    }
+
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/dispacher/MessageHandler.java

@@ -0,0 +1,20 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.dispacher;
+
+import io.netty.channel.Channel;
+
+public interface MessageHandler<T extends Message> {
+
+    /**
+     * 执行处理消息
+     *
+     * @param channel 通道
+     * @param message 消息
+     */
+    void execute(Channel channel, T message);
+
+    /**
+     * @return 消息类型，即每个 Message 实现类上的 TYPE 静态字段
+     */
+    String getType();
+
+}

lab-67/lab-67-netty-demo/lab-67-netty-demo-common/src/main/java/cn/iocoder/springboot/lab67/nettycommondemo/dispacher/MessageHandlerContainer.java

@@ -0,0 +1,76 @@
+package cn.iocoder.springboot.lab67.nettycommondemo.dispacher;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.aop.framework.AopProxyUtils;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ApplicationContext;
+
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+public class MessageHandlerContainer implements InitializingBean {
+
+    private Logger logger = LoggerFactory.getLogger(getClass());
+
+    /**
+     * 消息类型与 MessageHandler 的映射
+     */
+    private final Map<String, MessageHandler> handlers = new HashMap<>();
+
+    @Autowired
+    private ApplicationContext applicationContext;
+
+    @Override
+    public void afterPropertiesSet() throws Exception {
+        // 通过 ApplicationContext 获得所有 MessageHandler Bean
+        applicationContext.getBeansOfType(MessageHandler.class).values() // 获得所有 MessageHandler Bean
+                .forEach(messageHandler -> handlers.put(messageHandler.getType(), messageHandler)); // 添加到 handlers 中
+        logger.info("[afterPropertiesSet][消息处理器数量：{}]", handlers.size());
+    }
+
+    protected MessageHandler getMessageHandler(String type) {
+        MessageHandler handler = handlers.get(type);
+        if (handler == null) {
+            throw new IllegalArgumentException(String.format("类型(%s) 找不到匹配的 MessageHandler 处理器", type));
+        }
+        return handler;
+    }
+
+    public static Class<? extends Message> getMessageClass(MessageHandler handler) {
+        // 获得 Bean 对应的 Class 类名。因为有可能被 AOP 代理过。
+        Class<?> targetClass = AopProxyUtils.ultimateTargetClass(handler);
+        // 获得接口的 Type 数组
+        Type[] interfaces = targetClass.getGenericInterfaces();
+        Class<?> superclass = targetClass.getSuperclass();
+        while ((Objects.isNull(interfaces) || 0 == interfaces.length) && Objects.nonNull(superclass)) { // 此处，是以父类的接口为准
+            interfaces = superclass.getGenericInterfaces();
+            superclass = targetClass.getSuperclass();
+        }
+        if (Objects.nonNull(interfaces)) {
+            // 遍历 interfaces 数组
+            for (Type type : interfaces) {
+                // 要求 type 是泛型参数
+                if (type instanceof ParameterizedType) {
+                    ParameterizedType parameterizedType = (ParameterizedType) type;
+                    // 要求是 MessageHandler 接口
+                    if (Objects.equals(parameterizedType.getRawType(), MessageHandler.class)) {
+                        Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
+                        // 取首个元素
+                        if (Objects.nonNull(actualTypeArguments) && actualTypeArguments.length > 0) {
+                            return (Class<Message>) actualTypeArguments[0];
+                        } else {
+                            throw new IllegalStateException(String.format("类型(%s) 获得不到消息类型", handler));
+                        }
+                    }
+                }
+            }
+        }
+        throw new IllegalStateException(String.format("类型(%s) 获得不到消息类型", handler));
+    }
+
+}