Mybatis 缓存失效的几种情况
1 不在同一个sqlSession对象中
下面比较下载同一个sqlSession和不在同一sqlSession下面的两种情况：
同一sqlSession:
@Test
public final void testQueryClazzById() {
SqlSession session = sqlSessionFactory.openSession();
try {
ClazzMapper clazzMapper = session.getMapper(ClazzMapper.class);
Clazz clazz1 = clazzMapper.queryClazzById(1);
System.out.println("clazz1 = "+clazz1); Clazz clazz2 = clazzMapper.queryClazzById(1);
System.out.println("clazz2 = "+clazz2);
} finally {
session.close();
}
如下sql执行了一次，第二次queryClazzById没有执行sql,直接从缓存里面获取。
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz1 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
clazz2 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
不在同一sqlSession:
@Test
public final void testQueryClazzById() {
SqlSession session = sqlSessionFactory.openSession();
try {
ClazzMapper clazzMapper = session.getMapper(ClazzMapper.class);
Clazz clazz1 = clazzMapper.queryClazzById(1);
System.out.println("clazz1 = "+clazz1);
} finally {
session.close();
}
//緩存失效的四種情況
//不在同一個對象中
SqlSession session2 = sqlSessionFactory.openSession();
try {
ClazzMapper clazzMapper2 = session2.getMapper(ClazzMapper.class);
Clazz clazz2 = clazzMapper2.queryClazzById(1);
System.out.println("clazz2 = "+clazz2);
} finally {
session2.close();
}
}
看下结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz1 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Returned connection 1754638213 to pool.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Checked out connection 1754638213 from pool.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz2 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Returned connection 1754638213 to pool.
分别调用两次sql,没用使用缓存。
2 执行语句的参数不同。缓存中也不存在数据
@Test
public void testfirstCacheFail2() {
//一级缓存必须存在于同一个SqlSession中
SqlSession session = sqlSessionFactory.openSession();
ClazzMapper clazzMapper2 = session.getMapper(ClazzMapper.class);
Clazz user1 = clazzMapper2.queryClazzById(1);
System.out.println(user1); Clazz user2 = clazzMapper2.queryClazzById(2);
System.out.println( user2 );
session.close();
}
看结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <== Total: 2
Clazz [id=2, name=javaEE20170325, stus=[Student [id=4, name=stu0325_马云, clazz=null], Student [id=5, name=stu0325_任正非, clazz=null]]]
分别调用两次sql,没有使用到缓存。
3、执行增，删，改，语句，会清空掉缓存
@Test
public void testfirstCacheFail3() {
//一级缓存必须存在于同一个SqlSession中
SqlSession session = sqlSessionFactory.openSession();
ClazzMapper clazzMapper2 = session.getMapper(ClazzMapper.class);
Clazz user1 = clazzMapper2.queryClazzById(2);
System.out.println(user1); Clazz clazz = new Clazz();
clazz.setId(2);
clazz.setName("電影放映班");
clazzMapper2.updateClazz(clazz);
session.commit(); System.out.println(clazzMapper2.queryClazzById(2));
session.close();
}
看结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <== Total: 2
Clazz [id=2, name=javaEE20170325, stus=[Student [id=4, name=stu0325_马云, clazz=null], Student [id=5, name=stu0325_任正非, clazz=null]]]
DEBUG [main] - ==> Preparing: update t_clazz set name = ? where id = ?
DEBUG [main] - ==> Parameters: 電影放映班(String), 2(Integer)
DEBUG [main] - <== Updates: 1
DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <== Total: 2
Clazz [id=2, name=電影放映班, stus=[Student [id=4, name=stu0325_马云, clazz=null], Student [id=5, name=stu0325_任正非, clazz=null]]]
查询执行两次，更新执行一次，也没使用到缓存
4、手动清空缓存数据
@Test
public void testfirstCacheFail4() {
SqlSession session = sqlSessionFactory.openSession();
try {
ClazzMapper clazzMapper = session.getMapper(ClazzMapper.class);
Clazz clazz1 = clazzMapper.queryClazzById(1);
System.out.println("clazz1 = "+clazz1);
//清空緩存
session.clearCache();
Clazz clazz2 = clazzMapper.queryClazzById(1);
System.out.println("clazz2 = "+clazz2);
} finally {
session.close();
}
}
看结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz1 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz2 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
执行了两次sql,没有使用到缓存
1 不在同一个sqlSession对象中
下面比较下载同一个sqlSession和不在同一sqlSession下面的两种情况
<wiz_code_mirror>
1
@Test
2
public final void testQueryClazzById() {
3
SqlSession session = sqlSessionFactory.openSession();
4
try {
5
ClazzMapper clazzMapper = session.getMapper(ClazzMapper.class);
6
Clazz clazz1 = clazzMapper.queryClazzById(1);
7
System.out.println("clazz1 = "+clazz1);
8
9
Clazz clazz2 = clazzMapper.queryClazzById(1);
10
System.out.println("clazz2 = "+clazz2);
11
} finally {
12
session.close();
13
}
如下sql执行了一次，第二次queryClazzById没有执行sql,直接从缓存里面获取。
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz1 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
clazz2 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
<wiz_code_mirror>
1
@Test
2
public final void testQueryClazzById() {
3
SqlSession session = sqlSessionFactory.openSession();
4
try {
5
ClazzMapper clazzMapper = session.getMapper(ClazzMapper.class);
6
Clazz clazz1 = clazzMapper.queryClazzById(1);
7
System.out.println("clazz1 = "+clazz1);
8
} finally {
9
session.close();
10
}
11
//緩存失效的四種情況
12
//不在同一個對象中
13
SqlSession session2 = sqlSessionFactory.openSession();
14
try {
15
ClazzMapper clazzMapper2 = session2.getMapper(ClazzMapper.class);
16
Clazz clazz2 = clazzMapper2.queryClazzById(1);
17
System.out.println("clazz2 = "+clazz2);
18
} finally {
19
session2.close();
20
}
21
}
看下结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz1 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Returned connection 1754638213 to pool.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Checked out connection 1754638213 from pool.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz2 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - Returned connection 1754638213 to pool.
分别调用两次sql,没用使用缓存
2 执行语句的参数不同。缓存中也不存在数据
<wiz_code_mirror>
1
@Test
2
public void testfirstCacheFail2() {
3
//一级缓存必须存在于同一个SqlSession中
4
SqlSession session = sqlSessionFactory.openSession();
5
ClazzMapper clazzMapper2 = session.getMapper(ClazzMapper.class);
6
Clazz user1 = clazzMapper2.queryClazzById(1);
7
System.out.println(user1);
8
9
Clazz user2 = clazzMapper2.queryClazzById(2);
10
System.out.println( user2 );
11
session.close();
12
}
看结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <== Total: 2
Clazz [id=2, name=javaEE20170325, stus=[Student [id=4, name=stu0325_马云, clazz=null], Student [id=5, name=stu0325_任正非, clazz=null]]]
分别调用两次sql,没有使用到缓存
3、执行增，删，改，语句，会清空掉缓存
<wiz_code_mirror>
1
@Test
2
public void testfirstCacheFail3() {
3
//一级缓存必须存在于同一个SqlSession中
4
SqlSession session = sqlSessionFactory.openSession();
5
ClazzMapper clazzMapper2 = session.getMapper(ClazzMapper.class);
6
Clazz user1 = clazzMapper2.queryClazzById(2);
7
System.out.println(user1);
8
9
Clazz clazz = new Clazz();
10
clazz.setId(2);
11
clazz.setName("電影放映班");
12
clazzMapper2.updateClazz(clazz);
13
session.commit();
14
15
System.out.println(clazzMapper2.queryClazzById(2));
16
session.close();
17
}
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <== Total: 2
Clazz [id=2, name=javaEE20170325, stus=[Student [id=4, name=stu0325_马云, clazz=null], Student [id=5, name=stu0325_任正非, clazz=null]]]
DEBUG [main] - ==> Preparing: update t_clazz set name = ? where id = ?
DEBUG [main] - ==> Parameters: 電影放映班(String), 2(Integer)
DEBUG [main] - <== Updates: 1
DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6895a785]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 2(Integer)
DEBUG [main] - <== Total: 2
Clazz [id=2, name=電影放映班, stus=[Student [id=4, name=stu0325_马云, clazz=null], Student [id=5, name=stu0325_任正非, clazz=null]]]
查询执行两次，更新执行一次，也没使用到缓存
4、手动清空缓存数据
<wiz_code_mirror>
1
@Test
2
public void testfirstCacheFail4() {
3
SqlSession session = sqlSessionFactory.openSession();
4
try {
5
ClazzMapper clazzMapper = session.getMapper(ClazzMapper.class);
6
Clazz clazz1 = clazzMapper.queryClazzById(1);
7
System.out.println("clazz1 = "+clazz1);
8
//清空緩存
9
session.clearCache();
10
Clazz clazz2 = clazzMapper.queryClazzById(1);
11
System.out.println("clazz2 = "+clazz2);
12
} finally {
13
session.close();
14
}
15
}
看下结果：
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz1 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
DEBUG [main] - ==> Preparing: select c.*,s.id stu_id,s.name stu_name from t_clazz c left join t_student s on c.id = s.clazz_id where c.id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 3
clazz2 = Clazz [id=1, name=javaEE20170228, stus=[Student [id=1, name=stu0228_张三, clazz=null], Student [id=2, name=stu0228_李四, clazz=null], Student [id=3, name=stu0228_王五, clazz=null]]]
执行了两次sql,没有使用到缓存
Mybatis 缓存失效的几种情况的更多相关文章
- MySQL索引失效的几种情况
1.索引不存储null值 更准确的说,单列索引不存储null值,复合索引不存储全为null的值.索引不能存储Null,所以对这列采用is null条件时,因为索引上根本 没Null值,不能利用到索引, ...
- mysql索引总结(4)-MySQL索引失效的几种情况
mysql索引总结(1)-mysql 索引类型以及创建 mysql索引总结(2)-MySQL聚簇索引和非聚簇索引 mysql索引总结(3)-MySQL聚簇索引和非聚簇索引 mysql索引总结(4)-M ...
- C++迭代器失效的几种情况总结
一.序列式容器(数组式容器) 对于序列式容器(如vector,deque),序列式容器就是数组式容器,删除当前的iterator会使后面所有元素的iterator都失效.这是因为vetor,deque ...
- Spring事务失效的2种情况
使用默认的事务处理方式 因为在java的设计中,它认为不继承RuntimeException的异常是”checkException”或普通异常,如IOException,这些异常在java语法中是要求 ...
- Mysql索引会失效的几种情况分析（转）
出处:http://www.jb51.net/article/50649.htm 索引并不是时时都会生效的,比如以下几种情况,将导致索引失效: 1.如果条件中有or,即使其中有条件带索引也不会使用(这 ...
- oracle数据库中索引失效的几种情况
原文1:https://blog.csdn.net/u012255097/article/details/102792683 原文2:https://www.cnblogs.com/lanseyita ...
- vector迭代器失效的几种情况
在泛型编程还是STL的实际运用中,迭代器(iterator)无疑扮演者重要的角色.迭代器是一种类似于指针的对象(如可以内容提领,成员访问等),但他又不仅仅是一种普通的指针.关于迭代器失效,我们可以看下 ...
- sql 索引常见失效的几种情况
1. 对于联合索引,没有遵循左前缀原则 2. 索引的字段区分度不大,可能引起索引近乎全表扫描 3. 对于join操作,索引字段的编码不一致,导致使用索引失效 4.对于hash索引,范围查询失效,has ...
- Mysql索引会失效的几种情况
1.如果条件中有or,即使其中有条件带索引也不会使用(这也是为什么尽量少用or的原因): 2.对于多列索引,不是使用的第一部分,则不会使用索引: 3.like查询是以%开头: 4.如果列类型是字符串, ...
随机推荐
- IdentityServer4【QuickStart】之使用ResourceOwnerPassword流程来保护API
使用ResourceOwnerPassword流程来保护API OAuth2.0中的ResourceOwnerPassword授权流程允许一个客户端发送username和password到token服 ...
- 牛客练习赛13B 幸运数字2
题目链接:https://ac.nowcoder.com/acm/contest/70/B 题目大意: 略 分析: 先DFS求出所有幸运数,然后暴力即可 代码如下: #pragma GCC optim ...
- 利用 Docker 搭建单机的 Cloudera CDH 以及使用实践
想用 CDH 大礼包,于是先在 Mac 上和 Centos7.4 上分别搞个了单机的测试用.其实操作的流和使用到的命令差不多就一并说了: 首先前往官方下载包: https://www.cloudera ...
- 【转】Git 代码行统计命令集
查看git上个人代码量 git log --author="username" --pretty=tformat: --numstat | awk '{ add += $1; su ...
- java & jdk
java & jdk JDK 下载太慢 & java 12 https://download.oracle.com/otn-pub/java/jdk/12.0.1+12/69cfe15 ...
- 日志与python日志组件logging
1. 日志的相关概念: (1)日志的作用: a. 开发人员进行程序调试 b. 开发人员定位程序故障的位置 c. 运维人员观察应用运行是否正常 (2)日志的等级 a. DEBUG 最详细的日志,用于问题 ...
- Java之XML操作：从XML中直接获取数据
本文介绍如何将数据记录在XML文件中,然后通过DOM4J直接从XML中读取到数据. 依赖包: <dependency> <groupId>dom4j</groupId&g ...
- name设置id的方式 解决多个单选域冲突现象 同时有利于从动态网页取值
- JS 单线程和事件循环
Js 是单线程,js代码从上到下依次执行,比如我们写了两个函数,肯定是上面的函数先执行,下面的函数后执行.但是这种单线程有一个非常大的问题,那就是遇到耗时的任务,后面的任务只能等待它执行完,才能进行. ...
- linu系统文件授权命令