【MyBatis】缓存：让一级缓存失效

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public interface EmployeeMapper {
	public Employee getEmpById(Integer id);
	public Long addEmp(Employee employee);
}

public class MyBatisTest {
	

	public SqlSessionFactory getSqlSessionFactory() throws IOException {
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		return new SqlSessionFactoryBuilder().build(inputStream);
	}
	
	@Test
	public void testFirstLevelCache() throws IOException{
		SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
		SqlSession openSession = sqlSessionFactory.openSession();
		try{
			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class); //第1个sqlSession
			Employee emp01 = mapper.getEmpById(1);
			System.out.println(emp01);
			
			//【方式一】sqlSession不同。
			SqlSession openSession2 = sqlSessionFactory.openSession();  //再开启个sqlSession
			EmployeeMapper mapper2 = openSession2.getMapper(EmployeeMapper.class);
			Employee emp02 = mapper2.getEmpById(1);
			System.out.println(emp02);
			System.out.println(emp01==emp02);		







/*

			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class); //第1个sqlSession
			Employee emp01 = mapper.getEmpById(1);
			System.out.println(emp01);
			//【方式二】sqlSession相同，查询条件不同
			Employee emp02 = mapper.getEmpById(3);
			System.out.println(emp02);
			System.out.println(emp01==emp02);

*/	





/*

			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class); //第1个sqlSession
			Employee emp01 = mapper.getEmpById(1);
			System.out.println(emp01);
			
			//【方式三】sqlSession相同，两次查询间执行了增删改操作(这次增删改可能对当前数据有影响)
			mapper.addEmp(new Employee(null, "testCache", "cache", "1"));
			System.out.println("数据添加成功");
			
			
			Employee emp02 = mapper.getEmpById(1);  //但若查之前，修改了1号数据，则会再查
			System.out.println(emp02);
			System.out.println(emp01==emp02);
*/




/*
			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class); //第1个sqlSession
			Employee emp01 = mapper.getEmpById(1);
			System.out.println(emp01);
			
			//【方式四】sqlSession相同，手动清除了一级缓存（缓存清空）
			openSession.clearCache();
			
			Employee emp02 = mapper.getEmpById(1);  //但若查之前，修改了1号数据，则会再查
			System.out.println(emp02);
			System.out.println(emp01==emp02);

*/

		}finally{
			openSession2.close();
			openSession.close();
		}
	}
}

<?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.atguigu.mybatis.dao.EmployeeMapper">
	<select id="getEmpById" resultType="com.atguigu.mybatis.bean.Employee"
		databaseId="mysql" useCache="true">
		select * from tbl_employee where id = #{id}
	</select>
	<select id="getEmpById" resultType="com.atguigu.mybatis.bean.Employee"
		databaseId="oracle">
		select EMPLOYEE_ID id,LAST_NAME	lastName,EMAIL email 
		from employees where EMPLOYEE_ID=#{id}
	</select>
	<insert id="addEmp" parameterType="com.atguigu.mybatis.bean.Employee"
		useGeneratedKeys="true" keyProperty="id" databaseId="mysql"
		flushCache="true">
		insert into tbl_employee(last_name,email,gender) 
		values(#{lastName},#{email},#{gender})
	</insert>
</mapper>

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