mybatis

mybatis编写顺序和内容

第一步，新建maven项目

省略......

第二步，下载pom依赖，添加内容如下：

注意，如过想用lombok插件，光导入pom还不行，还需要再idea中下载plugin插件

<dependencies>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.7</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.22</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.16</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>RELEASE</version>
        <scope>compile</scope>
    </dependency>
</dependencies>

第三步，新建mybatis-config.xml（也可以是别的名字）配置mybatis配置文件，内容如下：

<?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>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://134.175.xxx.xxx:3306/testdb"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/test01/dao/UserDao.xml"/>
    </mappers>
</configuration>

第四步，编写数据库表的实体类，内容如下：

我这里用了lombok，所以没有写get，set方法

package com.test01.domain;


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

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Integer id;
    private String name;
    private Integer age;
}

第五步，编写dao映射接口

package com.test01.dao;

import com.test01.domain.User;

import java.util.List;

public interface UserDao {
    public List<User> findAll();
    public void insertData(User user);
    public void delData(User user);
    public void updateData(User user);
    public User findById(Integer id);
}

第六步，编写dao的xml映射文件

<?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.test01.dao.UserDao">
    <select id="findAll" resultType="com.test01.domain.User">
        select * from user;
    </select>
    <insert id="insertData" parameterType="com.test01.domain.User">
        insert into user (id, name, age) values (#{id},#{name},#{age});
    </insert>
    <delete id="delData" parameterType="com.test01.domain.User">
        delete from user where id=#{id}
    </delete>
    <update id="updateData" parameterType="com.test01.domain.User">
        update user set name=#{name} where id=#{id}
    </update>

    <select id="findById" parameterType="Integer" resultType="com.test01.domain.User">
        select * from user where id=#{id}
    </select>
</mapper>

最后目录结构如下：