Spring-Mybatis 练习_spring和mybatis项目练习

1.pojo中的User类

package com.ysj.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private int id;
    private String name;
    private String password;
}

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2.创建Mpper包中的Mapper

package com.ysj.mapper;

import com.ysj.pojo.User;

import java.util.List;

public interface UserMapper {
    List<User> getUsers();
}
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3.在2创建到之后在资源包中创建一个同名同包的UserMapper.xml用来写sql语句 mapmper的命名空间是本类的全称

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ysj.mapper.UserMapper">


    <select id="getUsers" resultType="user">
        select *
        from user;
    </select>
</mapper>
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4.接口类的实现

• 需要一个属性来获得与数据库的连接sqlSessionTemplate
• 在此实现类的同时就进行需要的操作，不需要在主函数或者test中写

package com.ysj.mapper;

import com.ysj.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;

import java.util.List;

public class UserMapperImpl implements UserMapper{
    //我们的所有的操作，都使用sqlSession来执行，在原来。而现在都使用sqlSessionTemplate；
    private SqlSessionTemplate sqlSession;

    public void setSqlSession(SqlSessionTemplate sqlSession) {
        this.sqlSession = sqlSession;
    }

    @Override
    public List<User> getUsers() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.getUsers();

    }
}
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5.配置文件的配置

• mybatis-config.xml可以不使用都放在spring-dao.xml中配置，使用经常在本文件中配置标签以及别名的使用标签

<?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核心配置文件-->
<configuration>

    <settings>
        <!--标准的日志工厂实现-->
        <setting name="logImpl" value="STDOUT_LOGGING"/>
        <!--是否开启自动驼峰命名规则(camel case)映射-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <!--显示的开启默认缓存-->
        <setting name="cacheEnabled" value="true"/>
    </settings>

    <typeAliases>
        <!--别用小写-->
        <package name="com.ysj.pojo"/>        
    </typeAliases>

</configuration>
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• spring-dao.xml的配置一般用来进行数据库的连接，降低耦合时可以不需改改动文件，要想更换数据库时直接改一些相关的配置，mapper文件的绑定也在此配置类似mybatis中的核心文件的配置都可以在里面配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
                           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--专注操作数据库  很少改内容-->


    <!--DataSource:使用Spring-的数据源替换Mybatis的配置-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url"
                  value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
        <property name="username" value="root"/>
        <property name="password" value="88888888"/>
    </bean>

    <!--sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!--绑定mybatis配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!--mapper的注册-->
        <property name="mapperLocations" value="classpath:com/ysj/mapper/UserMapper.xml"/>
        <!--别名的使用-->
        <property name="typeAliasesPackage" value="com.ysj.pojo"/>
    </bean>

    <!--SqlSessionTemplate:就是我们使用的sqlSession-->

    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--只能使用构造器注入sqlSessionFactory，因为没有set方法-->
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>

</beans>
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• applicationContext文件，可以作为核心文件，别的包的内容直接引进，文件还有一个作用就是，接口实现类的对象的创建在此创建

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
                           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--实现类的实例化，以及引用其他包，之后有后续直接引进本文件-->

    <import resource="spring-dao.xml"/>

    <bean id="userMapper" class="com.ysj.mapper.UserMapperImpl">
        <property name="sqlSession" ref="sqlSession"/>
    </bean>

</beans>
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6.test

package org.example;

import com.ysj.mapper.UserMapper;
import com.ysj.pojo.User;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

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

/**
 * Unit test for simple App.
 */
public class AppTest 
{
    @Test
    public void test1() throws IOException {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
        UserMapper userMapper = context.getBean("userMapper", UserMapper.class);
        List<User> users = userMapper.getUsers();
        for (User user : users) {
            System.out.println(user);
        }
    }
}
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注意事项（理解）：

• test中

    public void testAddUser() {
        //获得配置文件的信息
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //利用反射得到UserMapperImpl的对象
        UserMapper userMapper = context.getBean("userMapper", UserMapper.class);
        //反射得到的对象 调用方法
        userMapper.addUser(new User(7, "王小帅", "ai1234"));
    }
    public void testDeleteUser() {
    }
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• 实现类中

    @Override
    public int addUser(User user) {

        //sqlSession已经注入  得到UserMapper的代理
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //代理对象在进行操作xml中的addUser
        return mapper.addUser(user);
    } 
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