MyBatis的xml实现方式

1、该项目引入的依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.7.6</spring-boot.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>com.oopsguy.kaptcha</groupId>
            <artifactId>kaptcha-spring-boot-starter</artifactId>
            <version>1.0.0-beta-2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
            <version>4.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>com.example.demo.DemoApplication</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

2、引入配置文件

（1）yml的

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/mybatis_test?characterEncoding=utf8&useSSL=false
    username: 你的数据库名称
    password: 你的数据库密码
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  configuration: # 配置打印 MyBatis⽇志
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/**Mapper.xml

（2）properties的

#驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#数据库连接的url
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/mybatis_test?
characterEncoding=utf8&useSSL=false
#连接数据库的⽤⼾名
spring.datasource.username=root
#连接数据库的密码
spring.datasource.password=root
# 配置 mybatis xml 的⽂件路径，在 resources/mapper 创建所有表的 xml ⽂件
mybatis.mapper-locations=classpath:mapper/**Mapper.xml

3、我们设置的xml的固定格式

<?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.bite.mybatis.mapper.UserInfoXmlMapper">
    
</mapper>

4、查找操作（只有查询需要写 resultType="com.example.demo.UserInfo"）

（1）各个文件存放的位置

（2）接口代码

package com.example.demo;

import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface UserInfoXmlMapper {

    List<UserInfo> queryUserList();
}

（3）XML代码（一定要注意地址映射要正确）

<?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.example.demo.UserInfoXmlMapper">
       <select id="queryUserList" resultType="com.example.demo.UserInfo">
           select * from userinfo
       </select>
</mapper>

（4）测试部分代码（@SpringBootTest记得这个注解一定要加）

package com.example.demo;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.*;
@SpringBootTest
class UserInfoXmlMapperTest {
@Autowired
private UserInfoXmlMapper userInfoXmlMapper;
    @Test
    void queryUserList() {
        userInfoXmlMapper.queryUserList();
    }
}

5、插入操作

（1）接口部分代码

Integer insert(UserInfo userInfo);

（2）XML代码

<?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.example.demo.UserInfoXmlMapper">
       <select id="queryUserList" resultType="com.example.demo.UserInfo">
           select * from userinfo
       </select>
      <insert id="insert">
          insert into
          userinfo
          (username,password,age,gender,phone)
          values
          (#{username},#{password},#{age},#{gender},#{phone})
      </insert>
</mapper>

（3）测试部分代码

  @Test
    void insert() {
        UserInfo userInfo=new UserInfo();
        userInfo.setUsername("wanwu");
        userInfo.setAge(17);
        userInfo.setPassword("147258369");
        userInfo.setGender(1);
     userInfoXmlMapper.insert(userInfo);
    }

6、删除操作

（1）接口部分代码

Integer delete(Integer id);

（2）XML部分代码

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

（3）测试部分代码

 @Test
    void delete() {
        userInfoXmlMapper.delete(14);
    }

7、改操作

（1）接口部分代码

 Integer update(String password,Integer id);

（2）XML部分代码（idea创建的项目）

<update id="update">
        update userinfo set
        password=#{password}
        where id=#{id}
    </update>

（2）XML部分代码（阿里云创建的项目）

<update id="update">
        update userinfo set
        password=#{param1}
        where id=#{param2}
    </update>

（3）测试部分代码

 @Test
    void update() {
        userInfoXmlMapper.update("999999",15);
    }

8、mybatis赋值失败原因

（1）起别名

 <select id="queryUserList" resultType="com.example.demo.UserInfo">
           select delete_flag as deleteFlag from userinfo
       </select>

（2）通过resultmap方式（要记得把对象写全，id username等都映射上）

<resultMap id="base" type="com.example.demo.UserInfo">
   <result column="delete_flag" property="deleteFlag"></result>
</resultMap>
<select id="queryUserList" resultMap="base">
   select * from userinfo
</select>

（3）配置yml文件（驼峰命名）

mybatis:
 configuration:
   map-underscore-to-camel-case: true

9、返回自增主键

其他不变，和普通插入操作一样，就是在xml地方增加了一些设置

（1）xml地方代码

<insert id="insert" useGeneratedKeys="true" keyProperty="id">
   insert into
   userinfo
   (username,password,age,gender,phone)
   values
   (#{username},#{password},#{age},#{gender},#{phone})
</insert>

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