mybatis增删改查的写法集合

增删改查的写法集合

注意：xml文件尽量不要注释

• Usermapping

  public interface UserMapping {
  
      //查询
      List<User> getUserlist();
      User getUserById(int id);
  
      //增加元素
      int insertItem(User user);
  
      //删除元素
      int deleteItem(int i);
  
      //更改元素
      int updataItem(User user);
  }
  
  

• UserMapper.xml

  <?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.yunjiu.dao.UserMapping">
  
  
      <select id="getUserlist" resultType="com.yunjiu.pojo.User">
          select * from mybatis.user;
      </select>
  
      <select id="getUserById" parameterType="int" resultType="com.yunjiu.pojo.User">
        select  * from mybatis.user where id=#{id};
      </select>
  
  
      <insert id="insertItem" parameterType="com.yunjiu.pojo.User">
          insert into mybatis.user(id,name,pwd) values(#{id},#{name},#{pwd})
      </insert>
  
      <delete id="deleteItem" parameterType="int">
          delete from mybatis.user where id=#{i};
      </delete>
  
      <update id="updataItem" parameterType="com.yunjiu.pojo.User">
          update mybatis.user set name=#{name},pwd=#{pwd} where id=#{id};
      </update>
  </mapper>
  

• Mytest(测试文件)

import com.yunjiu.dao.UserMapping;
import com.yunjiu.pojo.User;
import com.yunjiu.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class MyTest {
    @Test
    public void selectUser() {
        SqlSession session = MybatisUtils.getSession();//使用工具类的方法

        //方法一:（不推荐使用）
        //List<User> users = session.selectList("com.kuang.mapper.UserMapper.selectUser");


        //方法二:
        UserMapping mapper = session.getMapper(UserMapping.class);//导入接口类
        List<User> users = mapper.getUserlist();//使用接口类的方法

        for (User user: users){
            System.out.println(user);
        }
        session.close();//注意，记得关
    }
    @Test
    public  void selectById(){
        SqlSession session = MybatisUtils.getSession();//使用工具类的方法

        UserMapping mapper = session.getMapper(UserMapping.class);//导入接口类
     User users = mapper.getUserById(1);//使用接口类的方法


            System.out.println(users);

        session.close();
    }
    @Test
    public  void insertItem(){
        SqlSession session = MybatisUtils.getSession();//使用工具类的方法

        UserMapping mapper = session.getMapper(UserMapping.class);//导入接口类
        int users = mapper.insertItem(new User(1,"白","15151"));//使用接口类的方法

if(users>0){
    System.out.println("增加成功");
    session.commit();//注意增删改查都需要提交才行
    session.close();
}
      else {
    System.out.println("增加失败");
    session.rollback();
    session.close();
      }

    }

    @Test
    public  void deleteItem(){
        SqlSession session = MybatisUtils.getSession();//使用工具类的方法

        UserMapping mapper = session.getMapper(UserMapping.class);//导入接口类
        int users = mapper.deleteItem(01);//使用接口类的方法

        if(users>0){
            System.out.println("删除成功");
            session.commit();//注意增删改查都需要提交才行
            session.close();
        }
        else {
            System.out.println("删除失败");
            session.rollback();
            session.close();
        }

    }
    @Test
    public  void updateItem(){
        SqlSession session = MybatisUtils.getSession();//使用工具类的方法

        UserMapping mapper = session.getMapper(UserMapping.class);//导入接口类
        int users = mapper.updataItem(new User(02,"白边","545"));//使用接口类的方法

        if(users>0){
            System.out.println("更新成功");
            session.commit();//注意增删改查都需要提交才行
            session.close();
        }
        else {
            System.out.println("更新失败");
            session.rollback();
            session.close();
        }

    }
}

核心配置文件

<?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="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>xml
    </environments>l
    <mappers>
        <mapper resource="com/yunjiu/dao/UserMapper.xml"/>
    </mappers>
</configuration>

• 实体类

  public class User {
  
      private int id;  //id
      private String name;   //姓名
      private String pwd;   //密码
  
      public User() {
  
      }
  
      public User(int id, String name, String pwd) {
          this.id = id;
          this.name = name;
          this.pwd = pwd;
      }
  
      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 String getPwd() {
          return pwd;
      }
  
      public void setPwd(String pwd) {
          this.pwd = pwd;
      }
  
      @Override
      public String toString() {
          return "User{" +
                  "id=" + id +java
                  ", name='" + name + '\'' +
                  ", pwd='" + pwd + '\'' +
                  '}';
      }
  }