目录
Redis介绍
Spring与Redis集成
Redis介绍
Redis是内存数据库，Key-value型NOSQL数据库，项目上经常将一些不经常变化并且反复查询的数据放入Redis缓存，由于数据放在内存中，所以查询、维护的速度远远快于硬盘方式操作数据（关系型数据库）。
Redis的数据存储在内存中，同时也会持久化到硬盘中，极端情况Redis服务器宕机时，缓存数据也可以从硬盘中恢复。
Redis的常用配置（配置文件redis.conf）如下：
-
daemonize yes 设置 Redis 以守护进程方式运行，启动后台运行
-
port 6379 设置 Redis 监听的端口，默认为 6379
-
logfile "/var/log/redis/redis-server.log" 设置 Redis 日志文件路径
-
databases 16 设置数据库数量，默认16个数据库 (0...15)
-
dir 设置数据文件目录
-
requirepass yourpassword 设置 Redis 密码
-
tcp-keepalive 300 设置客户端空闲超时时间
Redis操作缓存常用命令如下：
- select 选择数据库，select 0 选择0号数据库
- set 存放数据，命令格式为 set key value
- get 获取数据，命令格式为 get key
- keys 命令可以取符合规则的键值列表，通常情况可以结合*、?等选项来使用
- exists 命令可以判断键值是否存在
- del 命令可以删除当前数据库的指定 key
Spring与Redis集成
1、增加依赖【pom.xml】
重点依赖说明：jedis是java操作redis的客户端；spring-data-redis 是Spring和redis的集成包
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.2.20.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-redis</artifactId>
<version>2.3.6.RELEASE</version>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>3.7.1</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.0</version>
<scope>provided</scope>
</dependency>
</dependencies>2、Redis配置
Redis配置文件【redis_config.properties】
spring.redis.host=ip
spring.redis.port=port
spring.redis.password=password
spring.redis.database=0
Redis配置类【RedisConfig】，Spring IOC容器管理
package com.text.config;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.StringRedisSerializer;
@Configuration
@PropertySource("classpath:redis_config.properties")
public class RedisConfig {
@Value("${spring.redis.host}")
private String host;
@Value("${spring.redis.port}")
private Integer port;
@Value("${spring.redis.password}")
private String password;
@Value("${spring.redis.database}")
private Integer database;
@Bean
public RedisConnectionFactory redisConnectionFactory() {
RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration();
redisStandaloneConfiguration.setHostName(host);
redisStandaloneConfiguration.setPort(port);
redisStandaloneConfiguration.setPassword(password);
redisStandaloneConfiguration.setDatabase(database);
RedisConnectionFactory redisConnectionFactory = new JedisConnectionFactory(redisStandaloneConfiguration);
return redisConnectionFactory;
}
@Bean
public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory) {
RedisTemplate redisTemplate = new RedisTemplate();
redisTemplate.setConnectionFactory(redisConnectionFactory);
//设置key值的序列化方式，默认是JDK的形式
redisTemplate.setKeySerializer(StringRedisSerializer.UTF_8);
return redisTemplate;
}
}
重点代码说明：
- host ,port等属性值，来自于配置属性文件redis_config.properties
- 通过配置生成了RedisConnectionFactory，IOC容器管理
- 通过RedisConnectionFactory实例参数生成了RedisTemplate 实例，此实例对象就可以对Redis进行CRUD操作，IOC容器管理
Spring配置：此配置比较简单，只是开启了注解扫描包
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:task="http://www.springframework.org/schema/task"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/task
http://www.springframework.org/schema/task/spring-task.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">
<context:component-scan base-package="com.text"/>
</beans>3、测试类
package com.text.test;
import com.text.entity.Student;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
@Component
public class Application {
@Resource
private RedisTemplate redisTemplate;
public void testRedis() {
Student s1 = new Student("1","张三",18);
Student s2 = new Student("2","李四",19);
Student s3 = new Student("3","王五",20);
redisTemplate.opsForValue().set(s1.getId(),s1);
redisTemplate.opsForValue().set(s2.getId(),s2);
redisTemplate.opsForValue().set(s3.getId(),s3);
Student student = (Student)redisTemplate.opsForValue().get(s3.getId());
System.out.println(student);
}
public static void main(String[] args) throws Exception {
ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
RedisTemplate redisTemplate = context.getBean("redisTemplate", RedisTemplate.class);
System.out.println("redisTemplate:" + redisTemplate);
Application application = context.getBean("application", Application.class);
System.out.println("application:" + application);
application.testRedis();
}
}重点代码说明：
- 运行main程序后，spring容器启动，相关的对象都被实例化，包括Application，通过该实例对象注入的redisTemplate对象 set/get方法对Redis缓存进行操作。
- Student 对象需要序列化
package com.text.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student implements Serializable {
private String id;
private String name;
private int age;
}运行结果：
从运行结果可以看出，学生对象已经被加入缓存并且可以从缓存中读取出来，符合预期
