将RocketMQ集成到了Spring Boot项目中，实现站内信功能

1. 添加依赖

首先，在pom.xml中添加RocketMQ的依赖：

<dependencies>
    <!-- Spring Boot Starter Web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- Spring Boot Starter Data JPA -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <!-- H2 Database (或你选择的其他数据库) -->
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>

    <!-- Redis Cache -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis</artifactId>
    </dependency>

    <!-- RocketMQ -->
    <dependency>
        <groupId>org.apache.rocketmq</groupId>
        <artifactId>rocketmq-spring-boot-starter</artifactId>
        <version>2.2.1</version>
    </dependency>
</dependencies>

2. 配置文件

在application.properties中配置RocketMQ的相关信息：

# Redis Configuration
spring.redis.host=localhost
spring.redis.port=6379

# RocketMQ Configuration
rocketmq.name-server=localhost:9876
rocketmq.producer.group=my-producer-group

3. 数据模型

定义Message实体类：

package com.example.inbox.model;

import javax.persistence.*;
import java.time.LocalDateTime;

@Entity
public class Message {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String senderId;
    private String receiverId;
    private String subject;
    private String body;
    private LocalDateTime timestamp;
    private boolean read;

    // Getters and Setters
}

4. Repository接口

创建MessageRepository接口：

package com.example.inbox.repository;

import com.example.inbox.model.Message;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface MessageRepository extends JpaRepository<Message, Long> {
}

5. Service层

在Service层中集成缓存和RocketMQ的消息发送与接收：

package com.example.inbox.service;

import com.example.inbox.model.Message;
import com.example.inbox.repository.MessageRepository;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class MessageService {

    @Autowired
    private MessageRepository messageRepository;

    @Autowired
    private RocketMQTemplate rocketMQTemplate;

    @Cacheable(value = "messages", key = "#receiverId")
    public List<Message> getMessagesByReceiver(String receiverId) {
        return messageRepository.findByReceiverId(receiverId);
    }

    @CacheEvict(value = "messages", key = "#message.receiverId")
    public void sendMessage(Message message) {
        rocketMQTemplate.convertAndSend("messageTopic", message);
    }
}

6. 消息监听器

创建一个监听器来处理来自RocketMQ的消息：

package com.example.inbox.listener;

import com.alibaba.fastjson.JSON;
import com.example.inbox.model.Message;
import com.example.inbox.service.MessageService;
import org.apache.rocketmq.spring.annotation.RocketMQMessageListener;
import org.apache.rocketmq.spring.core.RocketMQListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
@RocketMQMessageListener(topic = "messageTopic", consumerGroup = "my-consumer-group")
public class MessageListener implements RocketMQListener<String> {

    @Autowired
    private MessageService messageService;

    @Override
    public void onMessage(String messageJson) {
        Message message = JSON.parseObject(messageJson, Message.class);
        message.setTimestamp(java.time.LocalDateTime.now());
        messageService.saveMessage(message);
    }
}

7. Controller

创建Controller来处理HTTP请求：

package com.example.inbox.controller;

import com.example.inbox.model.Message;
import com.example.inbox.service.MessageService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/messages")
public class MessageController {

    @Autowired
    private MessageService messageService;

    @GetMapping("/{receiverId}")
    public List<Message> getMessages(@PathVariable String receiverId) {
        return messageService.getMessagesByReceiver(receiverId);
    }

    @PostMapping
    public void sendMessage(@RequestBody Message message) {
        messageService.sendMessage(message);
    }
}

8. 启动类

确保你的Spring Boot应用启动类包含必要的注解：

package com.example.inbox;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;

@SpringBootApplication
@EnableCaching
public class InboxApplication {

    public static void main(String[] args) {
        SpringApplication.run(InboxApplication.class, args);
    }
}

总结

通过以上步骤，我们成功地将RocketMQ集成到了Spring Boot项目中，实现了站内信系统的异步处理。主要步骤包括：

1. 添加RocketMQ依赖 ：在pom.xml中添加RocketMQ相关的依赖。
2. 配置RocketMQ ：在application.properties中配置RocketMQ的相关参数。
3. 数据模型和Repository：定义实体类和Repository接口。
4. Service层：在Service层中集成RocketMQ的消息发送和Redis缓存。
5. 消息监听器 ：使用@RocketMQMessageListener注解创建消息监听器，处理接收到的消息。
6. Controller：创建RESTful API来处理HTTP请求。