Idea（Mybatis框架）中对SQL的增删改查

原创已于 2023-04-09 18:06:34 修改 · 3k 阅读

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文章标签：

#mybatis #intellij-idea #sql

于 2023-04-09 17:41:02 首次发布

本文详细介绍了如何创建原始数据库，然后逐步构建Mybatis框架，包括引入相关依赖、配置核心配置文件、创建实体类、映射接口以及测试类。最后展示了在Idea中进行MySQL的增删改查操作。

一：创建原始数据库

二：创建mybatis_1文件，搭建原始Mybatis框架

1：引入相关依赖

2：引入相关资源（config核心配置文件、db、log4j）

3：\src\main\java分别创建包（实体包、映射包、测试包）并创建相应的class类文件

4：创建实体包与映射链接接口

5：创建测试类（find查）

三：在Idea中写Mysql的增删改查

一：创建原始数据库

二：创建mybatis_1文件，搭建原始Mybatis框架

1：引入相关依赖

代码如下：xml

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.32</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.example</groupId>
        <artifactId>mybatis_1</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.12</version>
    </dependency>
</dependencies>

2：引入相关资源（config核心配置文件、db、log4j）

代码如下：

mybatis-config:

<?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>
    <!-- 环境配置 -->
    <!-- 加载类路径下的属性文件 -->
    <properties resource="db.properties"/>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <!-- 数据库连接相关配置 ,db.properties文件中的内容-->
            <dataSource type="POOLED">
                <property name="driver" value="${mysql.driver}"/>
                <property name="url" value="${mysql.url}"/>
                <property name="username" value="${mysql.username}"/>
                <property name="password" value="${mysql.password}"/>
            </dataSource>
        </environment>
    </environments>
    <!-- mapping文件路径配置 -->
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
    </mappers>

</configuration>

log4j代码：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
        <param name="Encoding" value="UTF-8"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n"/>
        </layout>
    </appender>
    <logger name="java.sql">
        <level value="debug"/>
    </logger>
    <logger name="org.apache.ibatis">
        <level value="info"/>
    </logger>
    <root>
        <level value="debug"/>
        <appender-ref ref="STDOUT"/>
    </root>
</log4j:configuration>

db代码：mybatis1是你创建数据库的名

mysql.driver=com.mysql.cj.jdbc.Driver
mysql.url=jdbc:mysql://localhost:3306/mybatis1?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false
mysql.username=root
mysql.password=123456

3：\src\main\java分别创建包（实体包、映射包、测试包）并创建相应的class类文件

①.pojo的class代码：

package org.example.pojo;

public class Users {

    private int id;
    private String name;
    private int age;
    private String sex;

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

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

    @Override
    public String toString() {
        return "Users{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                '}';
    }
}

②、Mapper和Utils的代码暂时不填

4：创建实体包与映射链接接口

UsersMapper代码如下：

<?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为映射的根节点-->
<!-- mapper为映射的根节点，namespace指定Dao接口的完整类名
mybatis会依据这个接口动态创建一个实现类去实现这个接口，
而这个实现类是一个Mapper对象-->
<mapper namespace="com.example.pojo.User">
    <!--id ="接口中的方法名"
　　parameterType="传入的参数类型"
　　resultType = "返回实体类对象，使用包.类名"-->
    <select id="findById" parameterType="int"
            resultType="com.example.pojo.User">
        select *
        from users
        where id = #{id}
   </select>
</mapper>

5：创建测试类

代码如下：

@Test
public void testFindUserById(){
    SqlSession session = MyBatisUtil.getSqlSession();

    UserMapper mapper = session.getMapper(UserMapper.class);
    User user = mapper.findUserById(1);
    System.out.println("user = " + user);

}

三：在Idea中写Mysql的增删改查

①：写映射类：

②：写映射文件：


<insert id="insertEmp" parameterType="Employee">
    insert into employee values(null, #{name}, #{age}, #{position});
</insert>

<!--public int updateEmpById(Employee employee);-->
<update id="updateEmpById" parameterType="employee">
    update employee set name=#{name}, age=#{age}, position = #{position} where id = #{id}
</update>

<!--public int deleteEmpById(int id);-->
<delete id="deleteEmpById" parameterType="int">
    delete from employee where id=#{id}
</delete>

③：写测试类：

public class TestUser {
    @Test
    public void testFindUserById(){
        SqlSession session = MyBatisUtil.getSqlSession();

        UserMapper mapper = session.getMapper(UserMapper.class);
        User user = mapper.findUserById(1);
        System.out.println("user = " + user);

    }

    @Test
    public void testInsertEmp(){
        SqlSession session = MyBatisUtil.getSqlSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        User emp = new User();
        emp.setUname("小米");
        emp.setUage(24);
        emp.setUid(3);
        int result = mapper.insertUser(emp);
    }


    @Test
    public void testUpdateEmp(){
        SqlSession session = MyBatisUtil.getSqlSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        User emp = new User();
        emp.setUid(4);
        emp.setUname("小明");
        emp.setUage(36);
        int result = mapper.updateUserById(emp);
    }

    @Test
    public void testDeleteEmpById(){
        SqlSession session = MyBatisUtil.getSqlSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        int result = mapper.delUserById(5);
    }

}

执行结果：