Mybatis一级缓存与二级缓存

测试

package cn.ps.lseeon04.check;

import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

/**
 * 1.解决sql硬编码的问题 
 * 2.解决面向对象面向问题 每一个对象一个xml文件(映射文件 MAPPING)
 * 
 */
public class TestMybatis {

	// 获取session对象
	public static SqlSession getSeesion() {
		// 获取config.xml文件
		String resources = "config.xml";
		// 读取config.xml文件
		InputStream resourceAsStream = TestMybatis.class.getResourceAsStream(resources);
		// sessopm工厂负责生产回话
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
		// 回话就是跟数据库产生的连接可以操作数据库的增删改查
		SqlSession openSession = sqlSessionFactory.openSession();
		return openSession;
	}

	/**
	 * 一级缓存: 会有内存溢出导致服务器奔溃 同一个seesion对象调用多次查询相同主键获取的数据发起一次sql语句 
	 */
	@Test
	public void testCheck() {
		SqlSession seesion = getSeesion();
		EmpMapper mapper = seesion.getMapper(EmpMapper.class);
		Emp queryEmp = mapper.queryEmp("7521");
		Emp queryEmp2 = mapper.queryEmp("7521");
		System.out.println(queryEmp == queryEmp2);
	}
	
	/**
	 * 二级缓存：数据存在redis里面数据库不会奔溃 同一个SqlSessiontory 不同的session对象
	 */
	@Test
	public void testSecondCheck() {
		String resources = "config.xml";
		InputStream resourceAsStream = TestMybatis.class.getResourceAsStream(resources);
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
		SqlSession openSession = sqlSessionFactory.openSession();
		SqlSession openSession1 = sqlSessionFactory.openSession();
		EmpMapper mapper = openSession.getMapper(EmpMapper.class);
		Emp queryEmp = mapper.queryEmp("7521");
		openSession.close();
		EmpMapper mapper1 = openSession1.getMapper(EmpMapper.class);
		Emp queryEmp1 = mapper1.queryEmp("7521");
		System.out.println(queryEmp==queryEmp1);
	}
}

实体类

package cn.ps.lseeon04.check;

import java.io.Serializable;
import java.util.List;

public class Emp implements Serializable{
	
	private String empno;
	
	private String ename;
	
	private int sal;
	
	private List empList;
	
	public List getEmpList() {
		return empList;
	}

	public void setEmpList(List empList) {
		this.empList = empList;
	}

	public String getEmpno() {
		return empno;
	}

	public void setEmpno(String empno) {
		this.empno = empno;
	}

	public String getEname() {
		return ename;
	}

	public void setEname(String ename) {
		this.ename = ename;
	}

	public int getSal() {
		return sal;
	}

	public void setSal(int sal) {
		this.sal = sal;
	}

	@Override
	public String toString() {
		return "Emp [empno=" + empno + ", ename=" + ename + ", sal=" + sal + "]";
	}
	
}

接口

package cn.ps.lseeon04.check;

public interface EmpMapper {
	
	public Emp queryEmp(String empno);
	
}

config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
	<properties resource="jdbc.properties"></properties>
	<!-- 控制台书库日志 -->
	<settings>
		<setting name="logImpl" value="STDOUT_LOGGING" />
	</settings>
	<!-- 给返回类型取别名 -->
	<typeAliases>
		<typeAlias type="cn.ps.lesson02.selectKey.User" alias="user" />
	</typeAliases>

	<plugins>
		<!-- com.github.pagehelper为PageHelper类所在包名 -->
		<plugin interceptor="com.github.pagehelper.PageInterceptor">
			<!-- 使用下面的方式配置参数，后面会有所有的参数介绍 -->
			<property name="supportMethodsArguments" value="true" />
		</plugin>
	</plugins>
	
	<!-- 连接数据库  -->
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="${driverClassName}" />
				<property name="url" value="${url}" />
				<property name="username" value="${userNames}" />
				<property name="password" value="${password}" />
			</dataSource>
		</environment>
	</environments>
	
	<!-- 扫描EmpMapper.xml文件 -->
	<mappers>
		<mapper resource="cn/ps/lseeon04/check/EmpMapper.xml"></mapper>
	</mappers>

</configuration>

EmpMapper.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="cn.ps.lseeon04.check.EmpMapper">
	<!-- 
		eviction:缓存的回收策略 FIFO:先进先出，按对象进入缓存的顺序来移除它们
		flushInterval:缓存刷新间隔,缓存多长时间清空一次，默认不清空，设置一个毫秒值
		size:缓存存放多少个元素
		type:指定自定义缓存的全类名(实现Cache接口即可)
	-->
	<cache eviction="FIFO" flushInterval="6000" size="512" type="org.mybatis.caches.redis.RedisCache"></cache>
	<select id="queryEmp" resultType="cn.ps.lseeon04.check.Emp">
		SELECT * FROM emp where empno = ${0}
	</select>
</mapper>

本文地址：https://blog.csdn.net/weixin_43728813/article/details/85982123