快取註解概念

安裝docker、redis

安裝docker

yum -y install docker-ce

 開機啟動docker

systemctl start docker

檢驗docker是否安裝成功

docker version

docker安裝redis

docker pull redis

docker檢測是否安裝成功redis

docker images

docker啟動redis並設定埠對映（-d表示後臺執行）

docker run -p 6379:6379 -d redis:latest myredis

檢視redis是否啟動成功

docker ps

 程式碼實現

在看程式碼前先看看目錄結構吧（在這裡使用ssm來整合redis）

資料庫表結構

pom.xml檔案，這裡主要是引入spring-boot-starter-cache依賴

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>

        <!-- mybatis 與 spring boot 2.x的整合包 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <!--mysql JDBC驅動 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.39</version>
        </dependency>
    </dependencies>

配置檔案application.yml，配置redis

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/spring_boot_cache?useUnicode=true
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: lzh

  redis:
    # 這是redis所在伺服器的ip
    host: 192.168.126.129
    timeout: 10000ms
    database: 0
    lettuce:
      pool:
        max-wait: -1ms
        max-active: 8
        max-idle: 8
        min-idle: 0
  cache:
    type: redis

啟動類加入@EnableCaching註解

package com.lzh.springbootstudytestcache;

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

@SpringBootApplication
@EnableCaching
public class SpringBootStudyTestCacheApplication {

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

UserController 類暴露介面

package com.lzh.springbootstudytestcache.controller;

import com.lzh.springbootstudytestcache.model.User;
import com.lzh.springbootstudytestcache.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author lzh
 * create 2019-09-24-20:34
 */
@RestController
public class UserController {

    @Autowired
    UserService userService;

    @GetMapping("/user/save")
    public User saveUser(@RequestParam Integer id,@RequestParam String name,@RequestParam Integer age){
        User user= userService.save(new User(id,name,age));
        return user;
    }

    @GetMapping("/user/{id}")
    public User getUserById(@PathVariable Integer id){

        System.out.println("id="+id);
        User user = userService.findUserById(id);

        System.out.println("getUserById - "+user);
        return user;
    }

    @GetMapping("/user/update")
    public User updateUser(@RequestParam Integer id,@RequestParam String name,@RequestParam Integer age){
        User user= userService.updateUser(new User(id,name,age));

        return user;
    }

    @GetMapping("/user/del/{id}")
    public String deleteUser(@PathVariable Integer id){
        System.out.println("id="+id);
        int num = userService.deleteUser(id);
        if (num > 0){
            return "刪除成功";
        } else {
            return "刪除失敗";
        }
    }

}

UserService介面

package com.lzh.springbootstudytestcache.service;

import com.lzh.springbootstudytestcache.model.User;

/**
 * @author lzh
 * create 2019-09-24-9:14
 */
public interface UserService {

    User save(User user);

    User findUserById(Integer id);

    User updateUser(User user);

    int deleteUser(Integer id);
}

UserService實現類

package com.lzh.springbootstudytestcache.service.impl;

import com.lzh.springbootstudytestcache.mapper.UserMapper;
import com.lzh.springbootstudytestcache.model.User;
import com.lzh.springbootstudytestcache.service.UserService;
import lombok.extern.log4j.Log4j2;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

/**
 * @author lzh
 * create 2019-09-24-9:14
 */
@Service
@Log4j2
public class UserServiceImpl implements UserService {

    @Autowired
    UserMapper userMapper;

    @Cacheable(value = "user",key = "#user.id")
    @Override
    public User save(User user) {
        int saveNum = userMapper.saveUser(user);
        System.out.println("saveNum="+saveNum);
        return user;
    }

    @Cacheable(value = "user",key = "#id")
    @Override
    public User findUserById(Integer id) {
        log.info("進入findUserById方法");
        return userMapper.findUserById(id);
    }

    @CachePut(value = "user", key = "#user.id")
    @Override
    public User updateUser(User user) {
        int num = userMapper.updateUser(user);
        System.out.println("num="+num);
        return user;
    }

    @CacheEvict(value = "user")
    @Override
    public int deleteUser(Integer id) {
        return userMapper.deleteUser(id);
    }
}

User實體類，加入@Data相當於加入getset方法，@AllArgsConstructor全參構造方法，@ToString重寫tostring方法，引入Lombok簡化程式碼

package com.lzh.springbootstudytestcache.model;


import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.ToString;

import java.io.Serializable;

/**
 * @author Levin
 * @since 2018/5/10 0007
 */
@Data
@AllArgsConstructor
@ToString
public class User implements Serializable {

    private Integer id;
    private String name;
    private Integer age;

}

UserMapper持久層，使用mybatis註解@Select、@Update、@Insert、@Delete實現

package com.lzh.springbootstudytestcache.mapper;

import com.lzh.springbootstudytestcache.model.User;
import org.apache.ibatis.annotations.*;

/**
 * @author lzh
 * create 2019-09-24-20:39
 */
@Mapper
public interface UserMapper {


    @Select("SELECT * FROM User WHERE id = #{id}")
    User findUserById(Integer id);

    @Update("update user set name=#{name},age=#{age} where id=#{id}")
    int updateUser(User user);

    @Insert("insert into user set name=#{name},age=#{age}")
    int saveUser(User user);

    @Delete("DELETE FROM USER WHERE id=#{id}")
    int deleteUser(Integer id);
}

改變預設jdk序列化器

package com.lzh.springbootstudytestcache.config;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.*;

/**
 * @author lzh
 * create 2019-09-24-22:22
 */
import org.springframework.cache.CacheManager;
import org.springframework.context.annotation.Primary;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.cache.RedisCacheWriter;

import java.time.Duration;

//@Configuration
public class MyRedisConfig {

    //@Bean(name = "redisTemplate")
    public RedisTemplate<String,Object> redisTemplate(RedisConnectionFactory redisConnectionFactory){

        RedisTemplate<String,Object> redisTemplate = new RedisTemplate<>();

        redisTemplate.setConnectionFactory(redisConnectionFactory);
        redisTemplate.setKeySerializer(keySerializer());
        redisTemplate.setHashKeySerializer(keySerializer());
        redisTemplate.setValueSerializer(valueSerializer());
        redisTemplate.setHashValueSerializer(valueSerializer());
        return redisTemplate;
    }

    //@Primary
    //@Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory){
        //快取配置物件
        RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig();

        redisCacheConfiguration = redisCacheConfiguration.entryTtl(Duration.ofMinutes(30L)) //設定快取的預設超時時間：30分鐘
                .disableCachingNullValues()             //如果是空值，不快取
                .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(keySerializer()))         //設定key序列化器
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer((valueSerializer())));  //設定value序列化器

        return RedisCacheManager
                .builder(RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory))
                .cacheDefaults(redisCacheConfiguration).build();
    }


    private RedisSerializer<String> keySerializer() {
        return new StringRedisSerializer();
    }

    private RedisSerializer<Object> valueSerializer() {
        return new GenericJackson2JsonRedisSerializer();
    }
}

測試

啟動srpingboot訪問http://localhost:8080/user/1

 使用redis視覺化工具檢視發現多了一個user物件，這就是在執行查詢語句的時候儲存的快取

 看控制檯這裡打印出了日誌，這是第一次查詢，說明執行了sql語句

 再次訪問http://localhost:8080/user/1，沒有執行findUserById方法說明沒有執行sql語句，而是直接從redis快取中讀取