使用MyBatis框架实现对数据库增删改查

墨蓝 2022-04-17 02:55 266阅读 0赞

第一步：首先需要新建一个数据库，然后建一个表在表里面可以随便插入几条数据，不插入也可以，等下直接用程序插入，今天就用下面这个表举例  
![这里写图片描述][SouthEast]

**第二步：创建一个Java工程；**  
![这里写图片描述][SouthEast 1]

**第三步：创建一个实体类User，将数据库中的字段名get、set。**

package com.zhiyuan.pojo;
    
    public class User {
        private int id;
        private String name;
        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 String getSex() {
            return sex;
        }
        public void setSex(String sex) {
            this.sex = sex;
        }
    
    }
     
      
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**第四步：写连接数据库的config.xml配置文件：**

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "mybatis-3-config.dtd" >
    <configuration>
    
        <typeAliases>
            <typeAlias alias="User" type="com.zhiyuan.pojo.User"/>
        </typeAliases>
    
        <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://127.0.0.1:3306/mybatis" />
                    <property name="username" value="root" />
                    <property name="password" value="liuxi" />  
                </dataSource>
            </environment>
        </environments>
    
        <mappers>
            <mapper resource="com/zhiyuan/pojo/User.xml" />
        </mappers>
    </configuration>
     
      
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**第五步：配置对应实体类的user.XML文件，里面写MySQL增删改查语句：**

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "mybatis-3-mapper.dtd" >
    <mapper namespace="com.zhiyuan.dao.Inter">
    
        
        <insert id="getInsert" parameterType="User">
            insert into nb(name,sex) values(#{name},#{sex})
        </insert>
    
        
        <select id="getUserList" resultType="com.zhiyuan.pojo.User">
            select * from nb
        </select>
    
        
        <select id="getUser" parameterType="int" resultType="com.zhiyuan.pojo.User">
            select * from nb where id=#{id}
        </select>
    
        
        <update id="getUpdate" parameterType="com.zhiyuan.pojo.User">
            update nb set name=#{name},sex=#{sex} where id=#{id}
        </update>
    
        
        <delete id="getDelete" parameterType="int">
            delete from nb where id=#{id}
        </delete>
    </mapper>
     
      
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第六步：写对应user.xml的接口类。

package com.zhiyuan.dao;
    
    import java.util.List;
    
    import com.zhiyuan.pojo.User;
    
    public interface Inter { 
        public List<User> getUserList();
        public User getUser(int id);
        public void getInsert(User user);
        public void getUpdate(User user);
        public void getDelete(int id);
    }
     
      
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最后一步写测试类：

package com.zhiyuan.main;
    
    import java.io.IOException;
    import java.io.Reader;
    import java.util.List;
    
    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 com.zhiyuan.dao.Inter;
    import com.zhiyuan.pojo.User;
    
    public class Main {
        static SqlSessionFactory ssf;
        static SqlSession ss;
        public static void main(String[] args) throws IOException {
            Reader re = Resources.getResourceAsReader("conf.xml");
            ssf = new SqlSessionFactoryBuilder().build(re);
            ss = ssf.openSession();
            insert();
    //      userList();
    //      user();
    //      update();
    //      delete();
        }
    
        //根据ID删除字段
        private static void delete() {
            ss = ssf.openSession();
            Inter ie = ss.getMapper(Inter.class);
            ie.getDelete(1);
            ss.commit();
            System.out.println("删除后：");
            userList();
        }
    
        //根据ID更新表数据
        private static void update() {
            ss = ssf.openSession();
            Inter ite = ss.getMapper(Inter.class);
            User us = ite.getUser(3);
            us.setName("徐深何");
            us.setSex("不详");
            ite.getUpdate(us);
            ss.commit();
            System.out.println("更新后:");
            userList();
        }
    
        //条件查询
        private static void user() {
            ss = ssf.openSession();
            Inter it = ss.getMapper(Inter.class);
            User user = it.getUser(3);
            if(user != null){
                System.out.println("姓名：" + user.getName());
                System.out.println( "性别：" + user.getSex());
            }
        }
    
        //查询全部
        private static void userList() {
            ss = ssf.openSession();
            Inter is = ss.getMapper(Inter.class);
            print(is.getUserList());
        }
        private static void print(List<User> userList) {
            for(User us : userList){
                System.out.println("编号：" + us.getId());
                System.out.println("姓名：" + us.getName());
                System.out.println("性别：" + us.getSex());
            }
        }
    
        //插入
        private static void insert() {
            ss = ssf.openSession();
            Inter in = ss.getMapper(Inter.class);
            User user = new User();
            user.setName("CSDN");
            user.setSex("????");
            in.getInsert(user);
            ss.commit();
            System.out.println("插入成功");
            userList();
        }
    
    }
     
      
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最后输出结果为：  
![这里写图片描述][SouthEast 2]  
这里值得注意得到地方就是写配置文件时一定要细心，不然写到最后一运行一定会出现各种各样的错，找起来头痛。

[SouthEast]: /images/20220417/92e02098273a4b7dbe1cf7908acd033c.png
[SouthEast 1]: /images/20220417/3e4dd3d4d4e7425888699a43e8efd572.png
[SouthEast 2]: /images/20220417/1c8754e7aeb14787a0fe5bb94ff47570.png