分类

基本步骤

第一步：编写核心配置文件mybatisConfig.xml文件
第二步：编写实体类User.class
第三步：编写Mapper配置文件userMappaer.xml文件
第四步：编写测试类userTest.class

注意事项

1. （.xml文件）配置文件里尽量不要编写汉字注释，极有可能报错
2. maven尽量配置自己的maven,自带的可能会发生某些错误
3. 核心配置文件中的usermapper.xml文件文件路径一定要写对，否者会报查找不到文件错误
4. 实体类User.class类中的属性名一定要和数据表中的字段名一致
5. 实体类中不要忘记编写toSting()方法，否者程序运行成功后打印出来得是地址而不是数据值
6. 事务代码块编写完毕后要提交事务，否则程序运行成功但实际数据表中的数据不受实际操作影响

##.编写mybatis核心配置文件
https://mybatis.org/mybatis-3/zh/getting-started.html

<?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="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="mapper.xml配置文件路径‘/0’"/>
  </mappers>
</configuration>

<?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.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="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/guolu/dao/userMapper.xml"/>
    </mappers>
</configuration>

编写User.class文件

package com.guolu;

public class User {
    int id;
    String name;
    String pwd;

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getPwd() {
        return pwd;
    }

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

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

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public String toString(){
        return ("User="+"{"
                + "id="+id+"\t"
                +"name="+name+"\t"
                +"pwd="+pwd+"\t"
                +"}");
    }
}

编写userMapper.xml配置文件

<?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="userMapper">
    <select id="selectTable" resultType="com.guolu.User">
        select *from user
    </select>
    <insert id="insertTable" parameterType="com.guolu.User">
        insert  into user values(#{id},#{name},#{pwd})
    </insert>
    <delete id="deleteTable" parameterType="com.guolu.User" >
        delete from user where id=#{id}
    </delete>
</mapper>

编写测试类 UserTest.class

package com.guolu.model;
import com.guolu.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class SelectTest {

    public static void main(String[] args) {

        try {
            InputStream resourceAsStream = Resources.getResourceAsStream("mybatisConfig.xml");
            //获得sqlSession工厂对象
            SqlSessionFactory sqlSessionFactory = new
                    SqlSessionFactoryBuilder().build(resourceAsStream);
            //获得sqlSession对象
            SqlSession sqlSession = sqlSessionFactory.openSession();
            //执行sql语句
            List<User> userList = sqlSession.selectList("userMapper.selectTable");
            //打印结果
            for (User users : userList) {
                System.out.println(users);
            }
             //提交事务
               sqlSession.commit()
            //释放资源
            sqlSession.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

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