Springboot结合 Mybatis 管理一二级缓存技术

作者: JohnYuCN | 来源:发表于2021-07-29 16:17 被阅读0次

一、默认整合后的状态：

与session相关的一级缓存打开
与sessionFactory相关的二级缓存关闭

二、调整及测试方式：

1. 一级缓存：

（1）默认值：session级，因为session的开闭是与事务相关的，同时项目的每个Mapper接口中的方法即为一个事务，这样相当于sessoin在mapper每次curd操作都会打开和关闭。此时业务方法中如果没有事务声明，则无法使用缓存数据。
（2）常用的对策：将事务设计在业务方法中，此时session的开闭就等同设置到了业务方法的边界上，这此在一个业务的多次mapper调用，就可以使用缓存的数据了。
（3）可选值：statement，相当于放弃一级缓存，此时即使同一个session的curd操作，都会直接操作数据库。
（4）具体操作的方法：

在applicaiton.yml中：

mybatis:
  configuration:
    local-cache-scope: session|statement

(5) 测试方法：
加入日志打印配置：application.yml

logging:
  level:
    cn:
      johnyu:
        mapper: trace

业务类，利用同一个id，调用了两次mapper：

@Component
// @Transactional: 加入和不加入两种选择
public class EmpServiceImpl implements EmpService {
    @Autowired
    private EmployeeMapper mapper;
    @Override
    public Employee load(int id) {
        Employee employee = mapper.load(id);
        Employee employee1 = mapper.load(id);
        System.out.println(employee==employee1);
        return employee;
    }

此时对业务进行调用后的日志结果如下：

业务无事务&& session情况下，结论：无法在业务中使用缓存数据，进行了两次查询，并且对象不相同！

2021-07-29 15:48:40.571 DEBUG 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 15:48:40.591 DEBUG 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 15:48:40.604 TRACE 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 15:48:40.605 TRACE 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 15:48:40.606 DEBUG 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
2021-07-29 15:48:40.611 DEBUG 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 15:48:40.611 DEBUG 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 15:48:40.612 TRACE 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 15:48:40.612 TRACE 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 15:48:40.612 DEBUG 32295 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
false

业务加入事务&& session情况下，结论：可以在业务中使用缓存数据，仅进行了一次查询，并且对象相同！

2021-07-29 15:51:50.703 DEBUG 32325 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 15:51:50.722 DEBUG 32325 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 15:51:50.736 TRACE 32325 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 15:51:50.736 TRACE 32325 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 15:51:50.738 DEBUG 32325 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
true

无论业务是否加入事务&& statement情况下，结论：无缓存数据

2021-07-29 15:53:27.566 DEBUG 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 15:53:27.585 DEBUG 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 15:53:27.599 TRACE 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 15:53:27.599 TRACE 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 15:53:27.600 DEBUG 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
2021-07-29 15:53:27.604 DEBUG 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 15:53:27.604 DEBUG 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 15:53:27.605 TRACE 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 15:53:27.605 TRACE 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 15:53:27.605 DEBUG 32342 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
false

2、二级缓存：

默认情况下，二级缓存是不开放的，如果二缓存打开，则可以跨session获取缓存在sessionFactory中的数据。
（1）打开的方法：
在applicaiton.yml中：

mybatis:
  configuration:
    cache-enabled: true

同时，在需要缓存的Mapper的映射文件中，加入<cache/>：

<mapper namespace="cn.johnyu.mapper.EmployeeMapper">
    <cache/>
    ...

(2) 测试：

不开启业务的事务 && session 情况：使用了二级缓存，但对象不为同一个。

2021-07-29 16:02:58.618 DEBUG 32435 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 16:02:58.638 DEBUG 32435 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 16:02:58.652 TRACE 32435 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 16:02:58.652 TRACE 32435 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 16:02:58.653 DEBUG 32435 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
2021-07-29 16:02:58.663  WARN 32435 --- [nio-8080-exec-1] o.apache.ibatis.io.SerialFilterChecker   : As you are using functionality that deserializes object streams, it is recommended to define the JEP-290 serial filter. Please refer to https://docs.oracle.com/pls/topic/lookup?ctx=javase15&id=GUID-8296D8E8-2B93-4B9A-856E-0A65AF9B8C66
2021-07-29 16:02:58.664 DEBUG 32435 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper          : Cache Hit Ratio [cn.johnyu.mapper.EmployeeMapper]: 0.5
false

开启了业务的事务 && session：虽然使用了二级缓存，但因为一级缓存数据优先使用，对象为同一个

2021-07-29 16:07:48.177 DEBUG 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper          : Cache Hit Ratio [cn.johnyu.mapper.EmployeeMapper]: 0.0
2021-07-29 16:07:48.184 DEBUG 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 16:07:48.204 DEBUG 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 16:07:48.218 TRACE 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 16:07:48.218 TRACE 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 16:07:48.219 DEBUG 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
2021-07-29 16:07:48.223 DEBUG 32480 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper          : Cache Hit Ratio [cn.johnyu.mapper.EmployeeMapper]: 0.0
true

无论是否开启了业务的事务 && statement：放弃使用一二级缓存，直接命中数据库

2021-07-29 16:12:53.762 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 16:12:53.782 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 16:12:53.796 TRACE 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 16:12:53.796 TRACE 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 16:12:53.797 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
2021-07-29 16:12:53.801 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper          : Cache Hit Ratio [cn.johnyu.mapper.EmployeeMapper]: 0.0
2021-07-29 16:12:53.802 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==>  Preparing: select empno as id,ename,job from emp where empno=?
2021-07-29 16:12:53.802 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : ==> Parameters: 7499(Integer)
2021-07-29 16:12:53.803 TRACE 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==    Columns: id, ename, job
2021-07-29 16:12:53.803 TRACE 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==        Row: 7499, ALLEN, SALESMAN
2021-07-29 16:12:53.803 DEBUG 32528 --- [nio-8080-exec-1] cn.johnyu.mapper.EmployeeMapper.load     : <==      Total: 1
false

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