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Mybatis如何通过注解开启使用二级缓存

2019-11-26 08:24:14
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这篇文章主要介绍了Mybatis基于注解开启使用二级缓存,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

本文主要是补充一下Mybatis中基于注解的二级缓存的开启使用方法。

1.在Mybatis的配置文件中开启二级缓存

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configuration    PUBLIC "-//mybatis.org//DTD Config 3.0//EN"    "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration>  <settings>    <!--开启全局的懒加载-->    <setting name="lazyLoadingEnabled" value="true"/>    <!--<!–关闭立即加载,其实不用配置,默认为false–>-->    <!--<setting name="aggressiveLazyLoading" value="false"/>-->    <!--开启Mybatis的sql执行相关信息打印-->    <setting name="logImpl" value="STDOUT_LOGGING" />    <!--默认是开启的,为了加强记忆,还是手动加上这个配置-->    <setting name="cacheEnabled" value="true"/>  </settings>  <typeAliases>    <typeAlias type="com.example.domain.User" alias="user"/>    <package name="com.example.domain"/>  </typeAliases>  <environments default="test">    <environment id="test">      <!--配置事务-->      <transactionManager type="jdbc"></transactionManager>      <!--配置连接池-->      <dataSource type="POOLED">        <property name="driver" value="com.mysql.jdbc.Driver"/>        <property name="url" value="jdbc:mysql://localhost:3306/test1"/>        <property name="username" value="root"/>        <property name="password" value="123456"/>      </dataSource>    </environment>  </environments>  <mappers>    <package name="com.example.dao"/>  </mappers></configuration>

开启缓存 <setting name="cacheEnabled" value="true"/>,为了查看Mybatis中查询的日志,添加 <setting name="logImpl" value="STDOUT_LOGGING" />开启日志的配置。

2.领域类以及Dao

public class User implements Serializable{  private Integer userId;  private String userName;  private Date userBirthday;  private String userSex;  private String userAddress;  private List<Account> accounts;  省略get和set方法...... }import com.example.domain.User;import org.apache.ibatis.annotations.*;import org.apache.ibatis.mapping.FetchType;import java.util.List;@CacheNamespace(blocking = true)public interface UserDao {  /**   * 查找所有用户   * @return   */  @Select("select * from User")  @Results(id = "userMap",value = {@Result(id = true,column = "id",property = "userId"),      @Result(column = "username",property = "userName"),      @Result(column = "birthday",property = "userBirthday"),      @Result(column = "sex",property = "userSex"),      @Result(column = "address",property = "userAddress"),      @Result(column = "id",property = "accounts",many = @Many(select = "com.example.dao.AccountDao.findAccountByUid",fetchType = FetchType.LAZY))  })  List<User> findAll();  /**   * 保存用户   * @param user   */  @Insert("insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})")  void saveUser(User user);  /**   * 更新用户   * @param user   */  @Update("update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id}")  void updateUser(User user);  /**   * 删除用户   * @param id   */  @Delete("delete from user where id=#{id}")  void deleteUser(Integer id);  /**   * 查询用户根据ID   * @param id   * @return   */  @Select("select * from user where id=#{id}")  @ResultMap(value = {"userMap"})  User findById(Integer id);  /**   * 根据用户名称查询用户   * @param name   * @return   *///  @Select("select * from user where username like #{name}")  @Select("select * from user where username like '%${value}%'")  List<User> findByUserName(String name);  /**   * 查询用户数量   * @return   */  @Select("select count(*) from user")  int findTotalUser();}

3.在对应的Dao类上面增加注释以开启二级缓存 

@CacheNamespace(blocking = true)

4.测试

public class UserCacheTest {  private InputStream in;  private SqlSessionFactory sqlSessionFactory;  @Before  public void init()throws Exception{    in = Resources.getResourceAsStream("SqlMapConfig.xml");    sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);  }  @After  public void destory()throws Exception{    in.close();  }  @Test  public void testFindById(){    //第一查询    SqlSession sqlSession1 = sqlSessionFactory.openSession();    UserDao userDao1 = sqlSession1.getMapper(UserDao.class);    User user1 = userDao1.findById(41);    System.out.println(user1);    //关闭一级缓存    sqlSession1.close();    //第二次查询    SqlSession sqlSession2 = sqlSessionFactory.openSession();    UserDao userDao2 = sqlSession2.getMapper(UserDao.class);    User user2 = userDao2.findById(41);    System.out.println(user2);    sqlSession1.close();    System.out.println(user1 == user2);  }}

(1)未开启二级缓存时

(2)开启二级缓存时

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