Mybatis中的的延迟加载、缓存和注解开发

Mybatis中的的延迟加载、缓存和注解开发 Mybatis中的的延迟加载、缓存和注解开发 1.Mybatis中的延迟加载

问题：在一对多中，当我们有一个用户，他有100个账户
在查询用户的时候，要不要把关联的账户查出来？
在查询账户的时候，要不要把我关联的用户查出来

在查询用户时，用户下的账户信息应该是什么时候使用，什么时候查询的

在查询账户时，账户的所属用户信息应该是睡着查询时一起查询出来的

解决：

延迟加载：在真正使用数据时才发起查询，不用的时候不查询，按需加载立即加载：不管用不用，只要一调用方法，马上发起查询

在对应的四种表关系中：一对多，多对一，多对多

一对多，多对多：通常情况下我们都是采用延迟加载多对一，一对一：通常情况请下我们采用立即加载
我们在查询mybatis的官方文档时，lazyLoadingEnable就是延迟加载全局开关，以及aggressiveLazyLoading调用加载该对象的属性

1.一对一代码实现：

Account实现类

package com.mybatisD.domain;

import java.io.Serializable;


public class Account  implements Serializable {
    private  Integer id;
    private Integer uid;
    private double money;
    private User user;

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", uid=" + uid +
                ", money=" + money +
                '}';
    }
}

User实现类

package com.mybatisD.domain;

import java.io.Serializable;
import java.util.Date;
import java.util.List;

public class User implements Serializable {
    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;
    //多对多的关系映射，一个用户可以具备多个角色
    private List roles;

    public List getRoles() {
        return roles;
    }

    public void setRoles(List roles) {
        this.roles = roles;
    }

    private List account;
//一对多关系映射，主表实体应该包含从表实体的集合引用
    public List getAccount() {

        return account;
    }

    public void setAccount(List account) {
        this.account = account;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", birthday=" + birthday +
                ", sex='" + sex + ''' +
                ", address='" + address + ''' +
                '}';
    }
}

IAccountDao接口

package com.mybatisD.dao;

import com.mybatisD.domain.Account;
import com.mybatisD.domain.AccountUser;

import java.util.List;

public interface IAccountDao {
    //查询所有账户
    List findAll();
    //查询账户，并且带有用户名称和地址信息
    List findAllAccount();
}

IUserDao接口

package com.mybatisD.dao;


import com.mybatisD.domain.QueryVo;
import com.mybatisD.domain.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;


public interface IUserDao {

   // 查询所有 *** 作
   // @Select("select * from user") 这是用注解方法
    //根据查询一个用户
    User findById(Integer userId);
  
}

IAccountDao.xml配置文件

    
    
        
        
        
        
        
    
    
        select * from account
    

 
IUserDao.xml配置文件
 



    
    
        select * from user where id=#{userid}
    

SqlMapConfig.xml配置文件
其中最主要的是

配置日志信息log4j.properties

log4j.rootCategory=debug,CONSOLE, LOGFILE
log4j.logger.org.apache.axis.enterprise=FATAL, ConSOLE
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x -%mn
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x -%mn

配置jdbc.properties数据库

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/newsql?characterEncoding=utf-8
jdbc.username=root
jdbc.password=

测试类

package com.mybatisJ.test;

import com.mybatisD.dao.IAccountDao;
import com.mybatisD.dao.IUserDao;
import com.mybatisD.domain.Account;
import com.mybatisD.domain.AccountUser;
import com.mybatisD.domain.QueryVo;
import com.mybatisD.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;


public class AccountTest {
    private InputStream in;
    private SqlSession sqlSession;
    private IAccountDao  accountDao;

    @Before//用于在测试方法执行之前执行
    public void init()throws  Exception{
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        sqlSession = factory.openSession();
        //4.使用SqlSession创建Dao接口的代理对象
        accountDao = sqlSession.getMapper(IAccountDao.class);
    }
    @After//用于在测试方法之后执行
    public void destory() throws Exception{
        //添加提交事物，不添加无法提交
        sqlSession.commit();
        sqlSession.close();
        in.close();
    }
    //查询连接方法其中包括用户的一些信息
    @Test
    public  void testFindAll() throws  Exception{

        List accounts = accountDao.findAll();
        for (Account account: accounts) {
            System.out.println("-----------------------");
            System.out.println(account);
           System.out.println(account.getUser());
        }
    }
    //查询account的信息
    @Test
    public void findAllAccount(){
        List accountUsers = accountDao.findAllAccount();
        for (AccountUser au: accountUsers) {
            System.out.println(au);
        }
    }
}

没有配置延迟加载时数据都是直接加载出来的其他信息

2.一对多的方式

Account与User实现类都不变，与上面的一致
改变的为IAccountDao接口

package com.mybatisD.dao;

import com.mybatisD.domain.Account;
import com.mybatisD.domain.AccountUser;

import java.util.List;

public interface IAccountDao {
    //查询所有账户
    List findAll();
    //查询账户，并且带有用户名称和地址信息
    List findAllAccount();
    //加入
    List findAccountByUid(Integer uid);
}

IAccountDao.xml的配置

    
    
        
        
        
        
        
    
    
        select * from account
    
    
    
       select * from account where uid=#{uid}
    

IUserDao.xml配置信息

    
    
            
            
            
            
            
        
        
        
    
    
    
       select * from user
    
    
    
        select * from user where id=#{userid}
    

测试类

package com.mybatisJ.test;

import com.mybatisD.dao.IAccountDao;
import com.mybatisD.dao.IUserDao;
import com.mybatisD.domain.Account;
import com.mybatisD.domain.AccountUser;
import com.mybatisD.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.List;


public class userTest {
    private InputStream in;
    private SqlSession sqlSession;
    private IUserDao userDao;

    @Before//用于在测试方法执行之前执行
    public void init()throws  Exception{
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        sqlSession = factory.openSession();
        //4.使用SqlSession创建Dao接口的代理对象
        userDao = sqlSession.getMapper(IUserDao.class);
    }
    @After//用于在测试方法之后执行
    public void destory() throws Exception{
        //添加提交事物，不添加无法提交
        sqlSession.commit();
        sqlSession.close();
        in.close();
    }
    //查询连接方法其中包括用户的一些信息
    @Test
    public  void testFindAll() throws  Exception{
        List users = userDao.findAll();
        for (User user: users) {
            System.out.println(user);
            System.out.println(user.getAccount());
        }
        }

}

结果，延迟加载就是在用到这个信息才会加载

2.mybatis中的缓存 1.缓存的概念

什么是缓存：存在于内存中的临时数据
为什么使用缓存：减少和数据库的交互次数，提高执行效率
什么样的数据能使用缓存：经常查询并且不经常改变的、数据的正确与否对最终的结果影响不大
不能使用缓存：经常改变的数据，数据的正确与否对最终的结果影响很大如：商品的库存，银行的汇率

2.Mybatis中的一级缓存和二级缓存

一级缓存是SqlSession范围的缓存，当调用SqlSession的修改，添加，删除，commit()提交，close()等方法时，就会清空一级缓存

一级缓存

它指的是Mybatis中SqlSession对象的缓存，当我们执行查询之后，查询的结果会同时存入到SqlSession为我们提供一块区域中，该区域的结构是一个Map，当我们再次查询同样的数据，Mybatis会先去SqlSession中查询是否有，有的话直接用，当SqlSession对象消失后，Mybatis的 一级缓存也就消失了

代码：
配置IUserDao.xml

在这里插入代码片`


    
    
    
       select * from user
    
`
 
测试中最主要的
 
  @Test
    public  void testFirstLevelchatch() throws  Exception{
      User user1 = userDao.findById(2);
        System.out.println("第一次查询"+user1);
        sqlSession.close();//是为了清除缓存
        //再次获取SqlSession
        //sqlSession.clearcache();  也是可以清空缓存
        sqlSession =factory.openSession();
        userDao = sqlSession.getMapper(IUserDao.class);
      User user2 = userDao.findById(2);
        System.out.println("第二次查询"+ user2);
        System.out.println(user1=user2);
        }
 
测试类
 
package com.mybatisJ.test;

import com.mybatisD.dao.IAccountDao;
import com.mybatisD.dao.IUserDao;
import com.mybatisD.domain.Account;
import com.mybatisD.domain.AccountUser;
import com.mybatisD.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.List;


public class userTest {
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession sqlSession;
    private IUserDao userDao;

    @Before//用于在测试方法执行之前执行
    public void init()throws  Exception{
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        factory = builder.build(in);
        sqlSession = factory.openSession();
        //4.使用SqlSession创建Dao接口的代理对象
        userDao = sqlSession.getMapper(IUserDao.class);
    }
    @After//用于在测试方法之后执行
    public void destory() throws Exception{
        //添加提交事物，不添加无法提交
        sqlSession.commit();
        sqlSession.close();
        in.close();
    }
    //一级缓存
    @Test
    public  void testFirstLevelchatch() throws  Exception{
      User user1 = userDao.findById(2);
        System.out.println("第一次查询"+user1);
        sqlSession.close();//是为了清除缓存
        //再次获取SqlSession
        //sqlSession.clearcache();  也是可以清空缓存
        sqlSession =factory.openSession();
        userDao = sqlSession.getMapper(IUserDao.class);
      User user2 = userDao.findById(2);
        System.out.println("第二次查询"+ user2);
        System.out.println(user1=user2);
        }

}

 
两次查询地址不一样，使用两次Connection第二次为缓存
 
 当使用update更新用户信息，一级缓存和数据库不一致了怎么办
 他会再次向数据库进行查询，不会再缓存里面查询
 一级缓存是SqlSession范围的缓存，当调用SqlSession的修改，添加，删除，commit()提交，close()等方法时，就会清空一级缓存
 
2.二级缓存 
它指的是Mybatis中SqlsessionFactory对象的缓存，由同一个SqlSessionFactory对象创建，其中创建的SqlSession共享其缓存
 
二级缓存的使用步骤：
 
1.让Mybatis框架支持二级缓存（在SqlMapConfig.xml中配置）2.让当前的映射文件支持二级缓存（在IUserDao.xml中配置）3.让当前的 *** 作支持二级缓存（在select标签中配置） 
配置SqlMapConfig.xml开启二级缓存
 




    
    
    
    
    
        
        
        
        
    
    
    
        
        
            
            
            
                
                
                
                
                
            
        
    
    
    
    
    
    
        
        
    

 
配置IUserDao.xml配置开启二级缓存
 



    
    
    
    
       select * from user
    
    
    
        select * from user where id=#{userid}
    
   

 
测试方法
 
package com.mybatisJ.test;

import com.mybatisD.dao.IUserDao;
import com.mybatisD.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.Date;

import com.mybatisD.dao.IAccountDao;
import com.mybatisD.dao.IUserDao;
import com.mybatisD.domain.Account;
import com.mybatisD.domain.AccountUser;
import com.mybatisD.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.Date;
import java.util.List;

public class SecondLeaveCatcheTest {
        private InputStream in;
        private SqlSessionFactory factory;


        @Before//用于在测试方法执行之前执行
        public void init()throws  Exception{
            in = Resources.getResourceAsStream("SqlMapConfig.xml");
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            factory = builder.build(in);

        }
        @After//用于在测试方法之后执行
        public void destory() throws Exception{
            in.close();
        }
        //一级缓存
        @Test
        public  void tesSecondChatch() throws  Exception {
            SqlSession sqlSession1 = factory.openSession();
            IUserDao dao1 =sqlSession1.getMapper(IUserDao.class);
            User user1 = dao1.findById(2);
            System.out.println(user1);
            sqlSession1.close(); //一级缓存消失

            SqlSession sqlSession2 = factory.openSession();
            IUserDao dao2 =sqlSession2.getMapper(IUserDao.class);
            User user2 = dao2.findById(2);
            System.out.println(user2);
            sqlSession2.close();
            System.out.println( user1 == user2);
        }

    }

 
结果
 
 

 
 其中的
 
 System.out.println( user1 == user2);
 
输出的是false
 
 
3.Mybatis的注解开发 
是使用注解将IUserDao.xml的配置进行注解
 
步骤：
 
环境搭建单表CRUD *** 作（代理Dao方式）多表查询的配置 
 

 最输入项目名称
 
下面进行设置Maven工程的配置，因为我是自己配置的所有不会出现什么麻烦
 
 
导入依赖
 
 
设置实现User类其中加入Account类是为了实现多对多的数据模式
 
package com.mybatisD.daomain;

import java.io.Serializable;
import java.util.Date;
import java.util.List;


public class User implements Serializable {
    private Integer id;
    private String username;
    private String address;
    private String sex;
    private Date birthday;
    //一对多关系映射，一个用户对应多个账户
    private List accounts;

    public List getAccounts() {
        return accounts;
    }

    public void setAccounts(List accounts) {
        this.accounts = accounts;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", address='" + address + ''' +
                ", sex='" + sex + ''' +
                ", birthday=" + birthday +
                '}';
    }
}


 
设置Account类其中加入User为的是实现多对多数据模式
 
package com.mybatisD.daomain;

import java.io.Serializable;


public class Account implements Serializable {
    private Integer id;
    private Integer uid;
    private double money;
    //多对一（mybatis中称之为一对一）的映射，一个账户只能属于一个用户
    private User user;

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public double getMoney() {
        return money;
    }

    public void setMoney(double money) {
        this.money = money;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", uid=" + uid +
                ", money=" + money +
                '}';
    }
}

 
IUserDao接口类
 
package com.mybatisD.dao;

import com.mybatisD.daomain.User;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.mapping.FetchType;

import java.util.List;

@CacheNamespace(blocking = true) //注解开启二级缓存，要在SqlMapConfig.xml里面开启二级缓存
public interface IUserDao {

    @Select("select * from user")
    List findAll();//查询所有用户

    
    @Insert("insert into user (username,address,sex,birthday) values(#{username},#{address},#{sex},#{birthday})")
    void saveUser(User user);

    
    @Update("update user set username=#{username} ,sex=#{sex},address=#{address},birthday=#{birthday} where id =#{id}")
    void updateUser(User user);

    
    @Delete("delete from user where id = #{id}")
    void deleteUser(Integer id);

    
    @Select("select * from user where id = #{id}")
    User findById(Integer id);

    
    @Select("select * from user where username like #{username}")
    //需要在测试类加入双%%号
    // @Select("select * from user where username like '%${value}%'")
    List findUserByName(String username);

    
    @Select("select count(*) from user")
    int findTotalUser();

    
    

    @Select("select * from user")
    @Results(value = {
            @Result(property = "accounts", column = "id", many = @Many(select = "com.mybatisD.dao.IAccount.findAccountByUid",fetchType = FetchType.LAZY))//LAZY是延迟
    })
    List findAllAccount();//查询所有用户

}

 
IAccountDao接口类
 
package com.mybatisD.dao;

import com.mybatisD.daomain.Account;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.mapping.FetchType;

import java.util.List;

public interface IAccountDao {
    
    @Select("select * from account")
    @Results(value = {
            @Result(id = true,column = "id",property = "id"),
            @Result(column = "uid",property = "uid"),
            @Result(column = "money",property = "money"),
            @Result(property = "user" ,column = "uid" ,one=@One(select = "com.mybatisD.dao.IUserDao.findById" ,fetchType = FetchType.EAGER))
    })
    List findAll();
    
    @Select("select * from account where uid = #{id}")
    List findAccountByUid(Integer id);
}

 
SqlMapConfig.xml配置
 




    
    
    
    
    
        
    
    
    
        
        
            
            
            
                
                
                
                
                
            
        
    
    
    
    
    
    

    
    
        
        
    

 
jdbc.properties数据连接
 
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/newsql?characterEncoding=utf-8
jdbc.username=root
jdbc.password=
 
日志信息配置log4j.properties
 
log4j.rootCategory=debug,CONSOLE, LOGFILE
log4j.logger.org.apache.axis.enterprise=FATAL, ConSOLE
log4j.appender.ConSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x -%mn
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x -%mn
 
User测试实现类
 
package com.mybateisT.TestD;

import com.mybatisD.dao.IUserDao;
import com.mybatisD.daomain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.List;


public class MybatisAnnoTest {
    
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession session;
    private IUserDao userDao;
    @Before
    public void init() throws IOException {
        //1.获取字节输入流
         in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.根据字节输入流构建SqlSessionFactory
        factory = new SqlSessionFactoryBuilder().build(in);
        //3.根据SqlSessionFactory生产一个SqlSession
        session = factory.openSession();
        //4.使用Selsession获取Dao代理对象
        userDao = session.getMapper(IUserDao.class);
        }
        @After
        public void destory() throws IOException {
        session.commit();
        session.close();
        in.close();
        }
    @Test
    public void TestFindAll() throws IOException {
        //5.执行Dao方法
        List users = userDao.findAll();
        for (User user: users) {
            System.out.println(user);
        }
    }
    @Test
    public void TestSave() {
        User user = new User();
        user.setUsername("test to annotation");
        user.setAddress("北极");
        user.setSex("女");
        user.setBirthday(new Date());
        userDao.saveUser(user);
        System.out.println(user);
    }
    @Test
    public void TestUpdate() {
        User user = new User();
        user.setId(3);
        user.setUsername("mybatis to annotation update");
        user.setAddress("北极");
        user.setSex("nv");
        user.setBirthday(new Date());
        userDao.updateUser(user);
        System.out.println(user);
    }
    @Test
    public void TestDelete() {
        List users = userDao.findAll();
        userDao.deleteUser(12);
        for (User user:users) {
            System.out.println(user);
        }
    }
    @Test
    public void TestFindOne() {
        User users = userDao.findById(1);
        System.out.println(users);
    }
    @Test
    public void TestFindName() {
        List users = userDao.findUserByName("%赵%");
        for (User user: users) {
            System.out.println(users);
        }
    }
    @Test
    public void TestTotal() {
        int total = userDao.findTotalUser();
        System.out.println(total);
    }
    @Test
    public void testFindAccount(){
        List users = userDao.findAllAccount();
        for (User user:users) {
            System.out.println("-----用户信息------");
           System.out.println(user);
            System.out.println(user.getAccounts());
        }
    }
}

 
Account测试实现类
 
package com.mybateisT.TestD;

import com.mybatisD.dao.IAccount;
import com.mybatisD.dao.IUserDao;
import com.mybatisD.daomain.Account;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


public class AccountTest {
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession session;
    private IAccount iAccount;
    @Before
    public void init() throws IOException {
        //1.获取字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.根据字节输入流构建SqlSessionFactory
        factory = new SqlSessionFactoryBuilder().build(in);
        //3.根据SqlSessionFactory生产一个SqlSession
        session = factory.openSession();
        //4.使用Selsession获取Dao代理对象
        iAccount = session.getMapper(IAccount.class);
    }
    @After
    public void destory() throws IOException {
        session.commit();
        session.close();
        in.close();
    }

    
    @Test
    public void testFindAllAccount(){
        List accounts = iAccount.findAll();
        for (Account account:accounts) {
            System.out.println("--------每个账户信息---------");
            System.out.println(account);
            System.out.println(account.getUser());
        }
    }
}

 
二级缓存测试实现类
 
package com.mybateisT.TestD;

import com.mybatisD.dao.IUserDao;
import com.mybatisD.daomain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


public class SecondLevelCatchTest {
    
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession session;
    private IUserDao userDao;
    @Before
    public void init() throws IOException {
        //1.获取字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.根据字节输入流构建SqlSessionFactory
        factory = new SqlSessionFactoryBuilder().build(in);
        //3.根据SqlSessionFactory生产一个SqlSession
        session = factory.openSession();
        //4.使用Selsession获取Dao代理对象
        userDao = session.getMapper(IUserDao.class);
    }
    @After
    public void destory() throws IOException {
        in.close();
    }
    @Test
    public void TestFindOne() throws IOException {
        //5.执行Dao方法
        User user = userDao.findById(1);
        System.out.println(user);
        session.close();//释放一级缓存
        SqlSession session1 = factory.openSession();//再次打开session
        IUserDao userDao1 = session1.getMapper(IUserDao.class);
        User user1 = userDao1.findById(1);
        System.out.println(user1);
        System.out.println(user==user1);

    }
}

 
文件结构
 
 数据库表
 
 
 
注解开发配置二级缓存现在SqlMapConfig.xml先配置
 
    
        
    
 
在IUserDao接口类加入注解@CacheNamespace开启二级缓存
 
@CacheNamespace(blocking = true) //注解开启二级缓存，要在SqlMapConfig.xml里面开启二级缓存
public interface IUserDao {

 
编写测类
 
package com.mybateisT.TestD;

import com.mybatisD.dao.IUserDao;
import com.mybatisD.daomain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


public class SecondLevelCatchTest {
    
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession session;
    private IUserDao userDao;
    @Before
    public void init() throws IOException {
        //1.获取字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.根据字节输入流构建SqlSessionFactory
        factory = new SqlSessionFactoryBuilder().build(in);
        //3.根据SqlSessionFactory生产一个SqlSession
        session = factory.openSession();
        //4.使用Selsession获取Dao代理对象
        userDao = session.getMapper(IUserDao.class);
    }
    @After
    public void destory() throws IOException {
        in.close();
    }
    @Test
    public void TestFindOne() throws IOException {
        //5.执行Dao方法
        User user = userDao.findById(1);
        System.out.println(user);
        session.close();//释放一级缓存
        SqlSession session1 = factory.openSession();//再次打开session
        IUserDao userDao1 = session1.getMapper(IUserDao.class);
        User user1 = userDao1.findById(1);
        System.out.println(user1);
        System.out.println(user==user1);

    }
}

 
 
2.还有什么问题可以留言给我，会尽心解答的，觉得文章不错的话点个赞把 
欢迎分享，转载请注明来源：内存溢出
原文地址:https://54852.com/zaji/5712754.html
缓存查询配置二级缓存方法
赞
(0)
打赏
微信扫一扫
支付宝扫一扫
都市网景一级用户组
00

生成海报
【java中的类型转换】
上一篇
2022-12-17
曹同学的ArrayList笔记

下一篇2022-12-17

发表评论

请登录后评论...
登录后才能评论
提交
评论列表（0条）

	



















保存