Spring Boot文档阅读笔记-Messaging with Redis-蒲公英云

首先要启动Redis服务端

redis-server

redis启动后会有如下信息：

[35142] 01 May 14:36:28.939 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
[35142] 01 May 14:36:28.940 * Max number of open files set to 10032
                _._
              _.-``__ ''-._
        _.-``    `.  `_.  ''-._           Redis 2.6.12 (00000000/0) 64 bit
    .-`` .-```.  ```\/    _.,_ ''-._
  (    '      ,       .-`  | `,    )     Running in stand alone mode
  |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
  |    `-._   `._    /     _.-'    |     PID: 35142
    `-._    `-._  `-./  _.-'    _.-'
  |`-._`-._    `-.__.-'    _.-'_.-'|
  |    `-._`-._        _.-'_.-'    |           https://redis.io
    `-._    `-._`-.__.-'_.-'    _.-'
  |`-._`-._    `-.__.-'    _.-'_.-'|
  |    `-._`-._        _.-'_.-'    |
    `-._    `-._`-.__.-'_.-'    _.-'
        `-._    `-.__.-'    _.-'
            `-._        _.-'
                `-.__.-'
[35142] 01 May 14:36:28.941 # Server started, Redis version 2.6.12
[35142] 01 May 14:36:28.941 * The server is now ready to accept connections on port 6379

Maven配置如下：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cn.it1995</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

创建Redis消息接受者

发布者发送消息，然后接受者接收消息，下面是创建一个接受者，带有接收消息的方法，代码如下：

package cn.it1995.demo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.atomic.AtomicInteger;
public class Receiver {
    private static final Logger LOGGER = LoggerFactory.getLogger(Receiver.class);
    private AtomicInteger counter = new AtomicInteger();
    public void receiveMessage(String message){
        LOGGER.info("Received <" + message + ">");
        counter.incrementAndGet();
    }
    public int getCount(){
        return counter.get();
    }
}

Receiver为POJO类定义了接收数据的方法。这里是要注册消息监听器监听Receiver的receiveMessage方法。

注册监听者及消息发布者

Spring Data Redis提供了send和receive的Redis等组件，要想使用这些功能需要下面3个配置：

A connection factory
A message listener container
A redis template

使用Redis template发送消息，将Receiver注册到监听容器里面，用于监听消息。connection factory包含了template和message listener连接redis服务的链接。

下面的代码使用了Spring Boot的默认的RedisConnectionFactory，这个类其实就是基于JedisConnectionFactory，这个JedisConnectionFactory是基于Jedis Redis库。连接工厂会被注入message listener容器和Redis template。代码如下：

package cn.it1995.demo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.listener.PatternTopic;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.data.redis.listener.adapter.MessageListenerAdapter;
@SpringBootApplication
public class DemoApplication {
    private static final Logger LOGGER = LoggerFactory.getLogger(DemoApplication.class);
    public static void main(String[] args) throws InterruptedException {
        ConfigurableApplicationContext ctx = SpringApplication.run(DemoApplication.class, args);
        StringRedisTemplate template = ctx.getBean(StringRedisTemplate.class);
        Receiver receiver = ctx.getBean(Receiver.class);
        while(receiver.getCount() == 0){
            LOGGER.info("Sending message...");
            template.convertAndSend("chat", "Hello From Redis");
            Thread.sleep(500L);
        }
    }
    @Bean
    StringRedisTemplate template(RedisConnectionFactory connectionFactory){
        return new StringRedisTemplate(connectionFactory);
    }
    @Bean
    RedisMessageListenerContainer container(RedisConnectionFactory connectionFactory, MessageListenerAdapter listenerAdapter){
        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        container.addMessageListener(listenerAdapter, new PatternTopic("chat"));
        return container;
    }
    @Bean
    MessageListenerAdapter listenerAdapter(Receiver receiver){
        return new MessageListenerAdapter(receiver, "receiveMessage");
    }
    @Bean
    Receiver receiver(){
        return new Receiver();
    }
}

listenrAdpter方法将Receiver类的receiveMessage方法注册到消息监听容器中，将会监听chat通道的数据。

application.properties：

# Redis服务器连接端口
spring.redis.port=6379
# Redis服务器地址
spring.redis.host=127.0.0.1
# Redis数据库索引（默认为0）
spring.redis.database=0
# Redis服务器连接密码（默认为空）
spring.redis.password=xxxxx
# 连接池最大连接数（使用负值表示没有限制）
spring.redis.jedis.pool.max-active=8
# 连接池最大阻塞等待时间（使用负值表示没有限制）
spring.redis.jedis.pool.max-wait=30000ms
# 连接池中的最大空闲连接
spring.redis.jedis.pool.max-idle=8
# 连接池中的最小空闲连接
spring.redis.jedis.pool.min-idle=0
# 连接超时时间（毫秒）
spring.redis.timeout=5000ms