看程序学mybatis 基础篇2- CRUD

最新推荐文章于 2025-03-23 11:32:53 发布

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最新推荐文章于 2025-03-23 11:32:53 发布

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分类专栏： mybatis

本文链接：https://blog.youkuaiyun.com/tujiahao1/article/details/94555197

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本文详细介绍了使用MyBatis框架进行增删查改(CRUD)操作的具体步骤，包括配置XML映射文件、执行SQL语句及代码实现，是MyBatis初学者不可多得的实践指南。

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步骤 1: 在前一步的基础上进行
通过Mybatis进行CRUD一套操作，建立在上一个知识点Mybatis 入门教程的基础上进行。
步骤 2 : 配置文件Category.xml
首先一次性修改配置文件Category.xml，提供CRUD对应的sql语句。
每个SQL如何使用在后续对应操作里一一讲解。

<?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.how2java.pojo">
        <insert id="addCategory" parameterType="Category" >
            insert into category_ ( name ) values (#{name})   
        </insert>
         
        <delete id="deleteCategory" parameterType="Category" >
            delete from category_ where id= #{id}  
        </delete>
         
        <select id="getCategory" parameterType="_int" resultType="Category">
            select * from   category_  where id= #{id}   
        </select>
 
        <update id="updateCategory" parameterType="Category" >
            update category_ set name=#{name} where id=#{id}   
        </update>
        <select id="listCategory" resultType="Category">
            select * from   category_     
        </select>    
    </mapper>

步骤 3 : 增加
运行之后，如图所示可以看到通过Mybatis查询出来的数据里有新增加的Category

通过session.insert调用addCategory对应的SQL语句

Category c = new Category();
c.setName(“新增加的Category”);
session.insert(“addCategory”,c);

addCategory对应的插入sql语句，#{name}会自动获取c对象的name属性值

insert into category_ ( name ) values (#{name})

TestMybatis.java :

package com.how2java;
 
import java.io.IOException;
import java.io.InputStream;
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.how2java.pojo.Category;
 
public class TestMybatis {
 
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
 
        Category c = new Category();
        c.setName("新增加的Category");
        session.insert("addCategory",c);
         
        listAll(session);
         
        session.commit();
        session.close();
 
    }
 
    private static void listAll(SqlSession session) {
        List<Category> cs = session.selectList("listCategory");
        for (Category c : cs) {
            System.out.println(c.getName());
        }
    }
}

代码片段：

insert into category_ ( name ) values (#{name})

在这里插入图片描述
步骤 4 : 删除
删除id=6的对象

Category c = new Category();
c.setId(6);
session.delete(“deleteCategory”,c);

deleteCategory对应删除的sql语句

delete from category_ where id= #{id} TestMybatis.java :

package com.how2java;
 
import java.io.IOException;
import java.io.InputStream;
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.how2java.pojo.Category;
 
public class TestMybatis {
 
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
 
        Category c = new Category();
        c.setId(6);
        session.delete("deleteCategory",c);
         
        listAll(session);
         
        session.commit();
        session.close();
 
    }
 
    private static void listAll(SqlSession session) {
        List<Category> cs = session.selectList("listCategory");
        for (Category c : cs) {
            System.out.println(c.getName());
        }
    }
}

代码片段：

delete from category_ where id= #{id}

步骤 5 : 获取
通过session.selectOne获取id=3的记录

Category c= session.selectOne(“getCategory”,3);

getCategory对应的sql语句：

select * from category_ where id= #{id}

TestMybatis.java :

package com.how2java;
 
import java.io.IOException;
import java.io.InputStream;
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.how2java.pojo.Category;
 
public class TestMybatis {
 
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
 
        Category c= session.selectOne("getCategory",3);
         
        System.out.println(c.getName());
         
//      listAll(session);
         
        session.commit();
        session.close();
 
    }
 
    private static void listAll(SqlSession session) {
        List<Category> cs = session.selectList("listCategory");
        for (Category c : cs) {
            System.out.println(c.getName());
        }
    }
}

代码片段：

select * from category_ where id= #{id}

步骤 6 : 修改
通过session.update进行修改

session.update(“updateCategory”,c);

updateCategory对应的sql语句：

update category_ set name=#{name} where id=#{id}

TestMybatis.java :

package com.how2java;
 
import java.io.IOException;
import java.io.InputStream;
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.how2java.pojo.Category;
 
public class TestMybatis {
 
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
 
        Category c= session.selectOne("getCategory",3);
        c.setName("修改了的Category名稱");
        session.update("updateCategory",c);
         
        listAll(session);
         
        session.commit();
        session.close();
 
    }
 
    private static void listAll(SqlSession session) {
        List<Category> cs = session.selectList("listCategory");
        for (Category c : cs) {
            System.out.println(c.getName());
        }
    }
}

代码片段：

update category_ set name=#{name} where id=#{id}

步骤 7 : 查询所有
session.selectList执行查询语句

List cs = session.selectList(“listCategory”);

listCategory对应的sql语句

select * from category_

TestMybatis.java :

package com.how2java;
 
import java.io.IOException;
import java.io.InputStream;
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.how2java.pojo.Category;
 
public class TestMybatis {
 
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
 
        listAll(session);
         
        session.commit();
        session.close();
 
    }
 
    private static void listAll(SqlSession session) {
        List<Category> cs = session.selectList("listCategory");
        for (Category c : cs) {
            System.out.println(c.getName());
        }
    }
}

代码片段：

select * from category_