spring整合Mybatis完成CRUD

spring整合Mybatis

1.Mybatis的核心组件

1.1 SqlSessionFactory:用于创建SqlSession的工厂类
1.2 SqlSession : Mybatis的核心组件,用于想数据库执行SQL
1.3 配置文件: XML配置文件,对Mybatis的底层行为做出详细的配置
1.4 Mapper接口:就是DAO接口,在Mybatis中习惯性的称为Mapper
1.5Mapper映射器:用于编写SQL,并将SQL和实体类映射的主键,采用XML,注解均可实现.

2.使用Mybatis整合Spring的流程

2.1 导入pom包依赖:
1. 访问mvnrepository.com搜索MySQL,复制依赖加进pom
2.搜索要整合的框架,在mvnrepository.com中搜索mybatis-spring或者Mybatis-springboot

2.2 在application.xml文件中,配置数据库连接
在springboot官方手册中有相关配置的模板:

	# DataSourceProperties
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/jtadmin?characterEncoding=utf-8&useSSL=false&serverTimezone=Hongkong
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.type=com.zaxxer.hikari.HikariDataSource
spring.datasource.hikari.maximum-pool-size=15
spring.datasource.hikari.minimum-idle=5
spring.datasource.hikari.idle-timeout=30000

# MybatisProperties
mybatis.mapper-locations=classpath:mapper/*.xml
mybatis.type-aliases-package=com.pg.pgcommunit.entity
mybatis.configuration.useGeneratedKeys=true
mybatis.configuration.mapUnderscoreToCamelCase=true

2.3 在dao层写入属性(最好以数据库字段名命名)

添加get,set方法,重写toString方法.

2.4 在service层添加接口,并写入CRUD接口方法(注解@Mapper不能忘记)

如果不添加@Mapper注解这一层就没有交给容器来管理,后期容器扫描不到这一层

2.5在resouce层下自己建的mapper文件夹下建一个xml文件写入头模板并添加sql语句

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.pg.pgcommunit.dao.UserMapper">
    
<select id="selectById" resultType="User">
    select * from demo_user where id = #{id}
</select>
    
    <insert id="insertUser" parameterType="User" keyProperty="id">
        insert into demo_user(name,age,sex) value (#{name},#{age},#{sex})
    </insert>

    <update id="updateUser">
        UPDATE demo_user SET name =#{name} WHERE id = #{id}
    </update>

    <delete id="deleteById">
        delete from demo_user where id =#{id}
    </delete>

</mapper>

< mapper namespace=“com.pg.pgcommunit.dao.UserMapper”>

namespace路径对应添加@Mapper注解的service层接口

< select id=“selectById” resultType=“User”>
注意添加返回值类型,类型一般为对应的dao层的属性类

< insert id=“insertUser” parameterType=“User” keyProperty=“id”>
插入方法多一个keyProperty id自增属性

2.6 测试类测试执行

@SpringBootTest
@ContextConfiguration(classes =PgCommunitApplication.class)
测试类需要加注解
大致代码如下:

@SpringBootTest
@ContextConfiguration(classes =PgCommunitApplication.class)
public class testCRUD {
    @Autowired
    private UserMapper userMapper;

    @Test
    public void testSelectById(){

        User user =  userMapper.selectById(1);
        System.out.println(user);
    }

    @Test
    public void testInsertUser(){
        User user = new User();
        user.setName("nihao");
        user.setAge(55);
        user.setSex("未知");
        int i = userMapper.insertUser(user);
        System.out.println(i);
    }

    @Test
    public void testUpdateUser(){
        User user = new User();
        user.setId(241);
        user.setName("你好");
        int i = userMapper.updateUser(user);
        System.out.println(i);
    }
    @Test
    public void testDeleteById(){
        User user = new User();
        user.setId(242);
        int i = userMapper.deleteById(user.getId());
        System.out.println(i);
    }

}

小白刚刚开始研究 如有不对的地方,欢迎大佬指出!