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