SpringBoot2.x【八】集成Redis缓存

SpringBoot2.x【八】集成Redis缓存

在此章，咱们将SpringBoot2.x集成Redis Cache，Redis是一个开源的，基于内存的数据结构存储，能够用做数据库、缓存和消息代理，在本章仅讲解缓存集成。

准备工做

当前项目工具及环境

• 开发工具 IDEA 2018.3
• 依赖管理 Gradle 5.0
• JDK 1.8
• Redis

如今去初始化一个Spring网站初始生成一个SpringBoot项目

Spring Boot Redis 项目生成

进入网站 start.spring.io/
咱们如今使用SPRING INITIALIZR工具生成一个初始化项目，在这里咱们初始了4个依赖包

点击生成下载过来一个zip包，解压以后导入IDEA工具就能够了

项目导入开发环境

build.gradle文件和maven的pom.xml类似，能够构建项目的依赖配置文件

在IDEA初始界面点击OPEN -> 选择文件 -> 找到.gradle文件 -> 选择Open —> Open as Project

这里的gradle环境是本地的，很简单安装配置，gradle官网下载二进制包而后解压，环境变量配置一下就可使用了

Spring Boot Redis Cache Gradle Dependencies

上面咱们已经初始化了一个项目依赖文件build.gradle，咱们也能够去手动修改而后添加或修改本身须要的依赖等

点击上图左上角中止下载，换成下面的国内源以后在加载gradle

build.gradle

buildscript {
	ext {
		springBootVersion = '2.1.1.RELEASE'
	}
	repositories {
		maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
		mavenCentral()
	}
	dependencies {
		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
	}
}

apply plugin: 'java'
apply plugin: 'idea'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
	maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
	mavenCentral()
}


dependencies {
	implementation('org.springframework.boot:spring-boot-starter-data-jpa')
	implementation('org.springframework.boot:spring-boot-starter-data-redis')
	implementation('org.springframework.boot:spring-boot-starter-web')
	runtimeOnly('com.h2database:h2')
	testImplementation('org.springframework.boot:spring-boot-starter-test')
}
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定义一个实体对象

要将数据存到redis，咱们须要定义一个实体来进行交互，并须要序列化实体对象

User.java

package com.example.rediscache.model;

import javax.persistence.*;
import java.io.Serializable;

@Entity
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @SequenceGenerator(name = "SEQ_GEN", sequenceName = "SEQ_USER", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_GEN")
    private Long id;
    private String name;
    private long money;

    public User() {
    }

    public User(String name, long money) {
        this.name = name;
        this.money = money;
    }

    //省略Getter 和 Setter
   
    @Override
    public String toString() {
        return String.format("User{id=%d, name='%s', money=%d}", id, name, money);
    }
}
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配置 Redis Cache

使用springboot的依赖咱们已经用gradle来完成，除此以外咱们还要配置下：
application.yml

# Redis Config
spring:
  cache:
    type: redis
  redis:
    host: localhost
    port: 6379
    password: pass1234

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基于JPA的简洁数据操做

UserRepository.java

package com.example.rediscache.repository;

import com.example.rediscache.model.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long> { }

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开启缓存并初始化数据

在启动类增长注解@EnableCaching开启缓存
并实现CommandLineRunner接口来执行启动完成以后的任务
RedisCacheApplication.java

package com.example.rediscache;

import com.example.rediscache.model.User;
import com.example.rediscache.repository.UserRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;

//springboot启动时执行任务CommandLineRunner
@SpringBootApplication
//开启缓存
@EnableCaching
public class RedisCacheApplication implements CommandLineRunner {

	private final UserRepository userRepository;

	private final Logger logger = LoggerFactory.getLogger(getClass());

	@Autowired
	public RedisCacheApplication(UserRepository userRepository) {
		this.userRepository = userRepository;
	}

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

	@Override
	public void run(String... args) throws Exception {
		logger.info("开始初始化user ->user count ->{}",userRepository.count());
		User james = new User("James", 2000);
		User potter = new User("Potter", 4000);
		User dumbledore = new User("Dumbledore", 999999);

		userRepository.save(james);
		userRepository.save(potter);
		userRepository.save(dumbledore);
		logger.info("初始化完成 数据-> {}.", userRepository.findAll());
	}
}
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控制层骨架

UserController.java

package com.example.rediscache.controller;

import com.example.rediscache.repository.UserRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.web.bind.annotation.*;

@RestController
public class UserController {

    private final Logger logger = LoggerFactory.getLogger(getClass());

    private final UserRepository userRepository;

    @Autowired
    public UserController(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
    
    //...dosomething
}

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如今测试缓存

当咱们数据库查询出来的值要放到缓存里，用@Cacheable注解

@Cacheable(value = "users", key = "#userId", unless = "#result.money < 10000")
    @RequestMapping(value = "/{userId}", method = RequestMethod.GET)
    public Object getUser(@PathVariable Long userId) {
        logger.info("获取user信息根据ID-> {}.", userId);
        return userRepository.findById(userId);
    }
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咱们访问 localhost:8080/1 和 localhost:8080/3 分别两次

发现id为3的就走了一次方法 说明缓存成功
id为1的走了两次是由于 unless里条件成立就不会缓存到redis

更新缓存

每次当咱们的数据库的值要更改，咱们缓存的也要更改 ，咱们可使用 @CachePut 注解

@CachePut(value = "users", key = "#user.id")
    @PutMapping("/update")
    public User updatePersonByID(@RequestBody User user) {
        userRepository.save(user);
        return user;
    }
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删除缓存

当咱们的数据从数据库删除，咱们也要从缓存进行删除,咱们可使用 @CacheEvict 注解
allEntries 是否清空全部缓存内容，缺省为 false，若是指定为 true，则方法调用后将当即清空全部缓存

@CacheEvict(value = "users", allEntries=true)
    @DeleteMapping("/{id}")
    public void deleteUserByID(@PathVariable Long id) {
        logger.info("删除用户根据ID-> {}", id);
        userRepository.deleteById(id);
    }
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在redis中查看已经没有了缓存

送上redis可视化工具 redis desktop manager for windows:
下载连接 : github.com/cuifuan/spr… redis desktop manager for mac:
下载连接：github.com/cuifuan/spr…