Mybatis 二级缓存简单示例
发布于: 2021 年 06 月 08 日
简介
简单接收 Mybatis 中二级缓存的使用示例
概览
主要部分如下：
引入 Maven 依赖
SpringBoot 配置文件配置、建库与初始化 SQL 语句
实体类与 Mapper 编写
测试
Maven 依赖
完整依赖大致如下：
<?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"> ...... <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>
<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.11</version> </dependency>
<dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.2.0</version> </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> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> <scope>test</scope> </dependency> </dependencies> ......</project>
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SpringBoot 配置文件配置、建库与初始化 SQL 语句
配置文件如下：
spring: datasource: url: jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&allowPublicKeyRetrieval=true&useSSL=false username: root password: root driver-class-name: com.mysql.cj.jdbc.Driver sql: init: schema-locations: classpath:mybatis/schema-mysql.sql data-locations: classpath:mybatis/data-mysql.sql
mybatis: configuration: cache-enabled: true mapper-locations: classpath:mybatis/mapper/*.xml
logging.level.com.example.cache.mapper: debug
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建库 DDL：
DROP TABLE IF EXISTS user;
CREATE TABLE user( id BIGINT(20) NOT NULL COMMENT '主键ID', name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名', age INT(11) NULL DEFAULT NULL COMMENT '年龄', email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱', PRIMARY KEY (id));
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数据初始化 DDL：
DELETE FROM `user`;
INSERT INTO `user` (id, name, age, email) VALUES(1, 'Jone', 18, 'test1@baomidou.com'),(2, 'Jack', 20, 'test2@baomidou.com'),(3, 'Tom', 28, 'test3@baomidou.com'),(4, 'Sandy', 21, 'test4@baomidou.com'),(5, 'Billie', 24, 'test5@baomidou.com');
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实体类与 Mapper 编写
User 实体类：
import lombok.Data;
import java.io.Serializable;
@Datapublic class User implements Serializable { private Long id; private String name; private Integer age; private String email;}
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UserMapper.java
import com.example.cache.entity.User;import org.springframework.stereotype.Repository;
import java.util.List;
@Repositorypublic interface UserMapper {
List<User> select();}
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UserMapper.xml
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.cache.mapper.UserMapper"><cache/> <select id="select" resultType="com.example.cache.entity.User"> select * from `user`; </select></mapper>
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测试
测试代码如下：
import com.example.cache.entity.User;import com.example.cache.mapper.UserMapper;import lombok.extern.slf4j.Slf4j;import org.junit.jupiter.api.Assertions;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTestpublic class UserTest {
@Autowired private UserMapper userMapper;
@Test public void testSelectOneCache() { List<User> users = userMapper.select(); Assertions.assertEquals(5, users.size()); users.forEach(System.out::println);
users = userMapper.select(); Assertions.assertEquals(5, users.size()); users.forEach(System.out::println); }}
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输出如下：
2021-06-08 22:38:48.925 DEBUG 7296 --- [ main] c.e.cache.mapper.UserMapper.select : ==> Preparing: select * from `user`;2021-06-08 22:38:48.950 DEBUG 7296 --- [ main] c.e.cache.mapper.UserMapper.select : ==> Parameters: 2021-06-08 22:38:48.979 DEBUG 7296 --- [ main] c.e.cache.mapper.UserMapper.select : <== Total: 5User(id=1, name=Jone, age=18, email=test1@baomidou.com)User(id=2, name=Jack, age=20, email=test2@baomidou.com)User(id=3, name=Tom, age=28, email=test3@baomidou.com)User(id=4, name=Sandy, age=21, email=test4@baomidou.com)User(id=5, name=Billie, age=24, email=test5@baomidou.com)2021-06-08 22:38:48.995 WARN 7296 --- [ main] o.apache.ibatis.io.SerialFilterChecker : As you are using functionality that deserializes object streams, it is recommended to define the JEP-290 serial filter. Please refer to https://docs.oracle.com/pls/topic/lookup?ctx=javase15&id=GUID-8296D8E8-2B93-4B9A-856E-0A65AF9B8C662021-06-08 22:38:48.997 DEBUG 7296 --- [ main] com.example.cache.mapper.UserMapper : Cache Hit Ratio [com.example.cache.mapper.UserMapper]: 0.5User(id=1, name=Jone, age=18, email=test1@baomidou.com)User(id=2, name=Jack, age=20, email=test2@baomidou.com)User(id=3, name=Tom, age=28, email=test3@baomidou.com)User(id=4, name=Sandy, age=21, email=test4@baomidou.com)User(id=5, name=Billie, age=24, email=test5@baomidou.com)
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可以看到第二次查询没有走 SQL 查询，直接从 Cache 中取得了结果
总结
一篇简单的 Mybatis 二级缓存的示例
从中可以看到，SpringBoot Mybatis 是默认开启二级缓存的，其他更多的使用，如缓存失效等，后面再探索
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发布于: 2021 年 06 月 08 日阅读数: 13
版权声明: 本文为 InfoQ 作者【萧】的原创文章。
原文链接:【http://xie.infoq.cn/article/c69c898a5b89b9c3a9cfb297c】。
本文遵守【CC-BY 4.0】协议，转载请保留原文出处及本版权声明。
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还未添加个人签名 2018.09.09 加入
代码是门手艺活，也是门艺术活
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