第六章.MyBatis缓存结构-白红宇

第六章.MyBatis缓存结构

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发布时间：2019-06-22

本文共 6217 字，大约阅读时间需要 20 分钟。

一级缓存

测试案例：

MyBatisTest.java

//缓存        @Test          public void testFindCustomerCache1() throws Exception{                            SqlSession sqlSession=dataConn.getSqlSession();                              //调用userMapper的方法              Customer customer1=sqlSession.selectOne("test.findCustomerById",1);            System.out.println("用户姓名："+customer1.getUsername());                                    Customer customer2=sqlSession.selectOne("test.findCustomerById",1);            System.out.println("用户姓名："+customer2.getUsername());            sqlSession.close();        }

测试结果：

只查询了一次

DEBUG [main] - ==>  Preparing: SELECT * FROM CUSTOMER WHERE cus_id=? DEBUG [main] - ==> Parameters: 1(Integer)DEBUG [main] - <==      Total: 1用户姓名：Mr用户姓名：MrDEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@42d8062c]

两次查询之间出现增删该查等情况时，即执行commit（）方法。

在UserMapper.xml最后面加上


     
              UPDATE CUSTOMER SET acno = #{acno} WHERE cus_id=#{cus_id}

在MyBatisTest.java中测试

@Test          public void testFindCustomerCache2() throws Exception{                            SqlSession sqlSession=dataConn.getSqlSession();                              //调用userMapper的方法              Customer customer1=sqlSession.selectOne("test.findCustomerById",1);            System.out.println("用户姓名："+customer1.getUsername()+"|"                    +"卡号："+customer1.getAcno());                        String AcNo = "6228289999999";            customer1.setAcno(AcNo);            System.out.println("修改用户卡号为："+AcNo);            sqlSession.update("test.updateCustomerAcNo",customer1);            sqlSession.commit();                        Customer customer2=sqlSession.selectOne("test.findCustomerById",1);            System.out.println("用户姓名："+customer2.getUsername()+"|"                    +"卡号："+customer2.getAcno());                        sqlSession.close();        }

观察结果：

com.mysql.jdbc.JDBC4Connection@42d8062c]DEBUG [main] - ==>  Preparing: SELECT * FROM CUSTOMER WHERE cus_id=? DEBUG [main] - ==> Parameters: 1(Integer)DEBUG [main] - <==      Total: 1用户姓名：Mr|卡号：622848修改用户卡号为：6228289999999DEBUG [main] - ==>  Preparing: UPDATE CUSTOMER SET acno = ? WHERE cus_id=? DEBUG [main] - ==> Parameters: 6228289999999(String), 1(Integer)DEBUG [main] - <==    Updates: 1DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@42d8062c]DEBUG [main] - ==>  Preparing: SELECT * FROM CUSTOMER WHERE cus_id=? DEBUG [main] - ==> Parameters: 1(Integer)DEBUG [main] - <==      Total: 1用户姓名：Mr|卡号：6228289999999DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@42d8062c]DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@42d8062c]DEBUG [main] - Returned connection 1121453612 to pool.

二级缓存

检查Customer.java文件

属性以及是否实现序列化接口

public class Customer implements Serializable{    private int cus_id;    private String username;    private String acno;    private String gender;    private String phone;    private List
     
       batchList; .... }

在MyBatisTest.java中测试

@Test          public void testFindCustomerOnMapper1() throws Exception{              SqlSession sqlSession=dataConn.getSqlSession();                              //获取Mapper代理              CustomerMapper customerMapper1=sqlSession.getMapper(CustomerMapper.class);            //执行Mapper代理对象的查询方法            Customer customer1=customerMapper1.findCustomerById(1);            System.out.println("用户姓名："+customer1.getUsername()+"|"                    +"卡号："+customer1.getAcno());                            //获取Mapper代理              CustomerMapper customerMapper2=sqlSession.getMapper(CustomerMapper.class);            //执行Mapper代理对象的查询方法            Customer customer2=customerMapper2.findCustomerById(1);            System.out.println("用户姓名："+customer2.getUsername()+"|"                    +"卡号："+customer2.getAcno());                        sqlSession.close();        }

得到结果：

DEBUG [main] - ==>  Preparing: SELECT * FROM CUSTOMER WHERE cus_id=? DEBUG [main] - ==> Parameters: 1(Integer)DEBUG [main] - <==      Total: 1用户姓名：Mr|卡号：622828999999用户姓名：Mr|卡号：622828999999

若二级缓存中两个查询之间多出了commit()方法的执行？

MyBatisTest.java继续测试

@Test          public void testFindCustomerOnMapper2() throws Exception{              SqlSession sqlSession=dataConn.getSqlSession();                              //获取Mapper代理              CustomerMapper customerMapper1=sqlSession.getMapper(CustomerMapper.class);            //执行Mapper代理对象的查询方法            Customer customer1=customerMapper1.findCustomerById(1);            System.out.println("用户姓名："+customer1.getUsername()+"|"                    +"卡号："+customer1.getAcno());                        //获取Mapper代理              CustomerMapper customerMapper2=sqlSession.getMapper(CustomerMapper.class);            String AcNo = "6228286666666";            customer1.setAcno(AcNo);            //执行Mapper代理对象的修改方法            customerMapper2.updateCustomerAcNo(customer1);            System.out.println("修改用户姓名："+customer1.getUsername()+"|"                    +"的卡号为："+customer1.getAcno());            sqlSession.commit();                        //获取Mapper代理              CustomerMapper customerMapper3=sqlSession.getMapper(CustomerMapper.class);            //执行Mapper代理对象的查询方法            Customer customer3=customerMapper3.findCustomerById(1);            System.out.println("用户姓名："+customer3.getUsername()+"|"                    +"卡号："+customer3.getAcno());                        sqlSession.close();        }

测试结果：

DEBUG [main] - ==>  Preparing: SELECT * FROM CUSTOMER WHERE cus_id=? DEBUG [main] - ==> Parameters: 1(Integer)DEBUG [main] - <==      Total: 1用户姓名：Mr|卡号：622828999999DEBUG [main] - ==>  Preparing: UPDATE CUSTOMER SET acno = ? WHERE cus_id=? DEBUG [main] - ==> Parameters: 6228286666666(String), 1(Integer)DEBUG [main] - <==    Updates: 1修改用户姓名：Mr|的卡号为：6228286666666DEBUG [main] - Committing JDBC Connection [com.mysql.jdbc.JDBC4Connection@13c27452]DEBUG [main] - ==>  Preparing: SELECT * FROM CUSTOMER WHERE cus_id=? DEBUG [main] - ==> Parameters: 1(Integer)DEBUG [main] - <==      Total: 1用户姓名：Mr|卡号：6228286666666DEBUG [main] - Resetting autocommit to true on JDBC Connection

转载于:https://www.cnblogs.com/Mrchengs/p/9811002.html

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