MyBatis笔记（五）--------缓存

• 缓存概念
• 一级缓存
• 二级缓存
• • 可能遇到的问题

public void getBlogByID(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        blogMapper mapper = sqlSession.getMapper(blogMapper.class);

        Blog blogById1 = mapper.getBlogById("1");
        Blog blogById2 = mapper.getBlogById("1");

        System.out.println(blogById1);
        System.out.println(blogById2);
        System.out.println("======================");
        System.out.println(blogById1==blogById2);
        
        sqlSession.close();
    }

即使增删改的数据不是缓存中的数据，缓存也会刷新
手动刷新缓存：sqlSession.clearCache();

public void getBlogById(){
        SqlSession sqlSession1 = MybatisUtils.getSqlSession();
        SqlSession sqlSession2 = MybatisUtils.getSqlSession();

        blogMapper mapper1 = sqlSession1.getMapper(blogMapper.class);
        Blog blogById1 = mapper1.getBlogById("1");
        System.out.println(blogById1);
        sqlSession1.close();

        blogMapper mapper2 = sqlSession2.getMapper(blogMapper.class);
        Blog blogById2 = mapper2.getBlogById("1");
        System.out.println(blogById2);
        System.out.println("==========================");
        System.out.println(blogById1==blogById2);

        sqlSession2.close();
    }

sql查询的顺序

如果开启缓存时直接写;没有自定义配置，可能会报实体类没有序列化的错误

将实体类序列化即可