Mybatis框架快速入门超详细教程_Java

mybatis 是一款支持定制化 sql、存储过程以及高级映射的轻量级半自动 orm 框架。它不仅仅可以与mysql一起用，pg也可以。

想要了解更多可以去官网看看，里面有中文版。

一、开发步骤

1. 添加mybatis坐标

<project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
  xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelversion>4.0.0</modelversion>
  <groupid>com.itheima</groupid>
  <artifactid>ithiema_mybatis_quick</artifactid>
  <packaging>war</packaging>
  <version>1.0-snapshot</version>
  <name>ithiema_mybatis_quick maven webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupid>junit</groupid>
      <artifactid>junit</artifactid>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
      <dependency>
          <groupid>com.mchange</groupid>
          <artifactid>c3p0</artifactid>
          <version>0.9.5.2</version>
      </dependency>
      <dependency>
          <groupid>mysql</groupid>
          <artifactid>mysql-connector-java</artifactid>
          <version>8.0.28</version>
      </dependency>
      <dependency>
          <groupid>com.alibaba</groupid>
          <artifactid>druid</artifactid>
          <version>1.1.21</version>
      </dependency>
      <dependency>
          <groupid>org.junit.jupiter</groupid>
          <artifactid>junit-jupiter</artifactid>
          <version>release</version>
          <scope>compile</scope>
      </dependency>
      <dependency>
          <groupid>org.springframework</groupid>
          <artifactid>spring-context</artifactid>
          <version>6.1.2</version>
      </dependency>
      <dependency>
          <groupid>org.springframework</groupid>
          <artifactid>spring-test</artifactid>
          <version>5.3.12</version>
      </dependency>
      <dependency>
          <groupid>javax.servlet</groupid>
          <artifactid>javax.servlet-api</artifactid>
          <version>4.0.1</version>
      </dependency>
      <dependency>
          <groupid>javax.servlet.jsp</groupid>
          <artifactid>javax.servlet.jsp-api</artifactid>
          <version>2.3.3</version>
      </dependency>
      <dependency>
          <groupid>org.springframework</groupid>
          <artifactid>spring-web</artifactid>
          <version>6.1.2</version>
      </dependency>
      <dependency>
          <groupid>org.springframework</groupid>
          <artifactid>spring-webmvc</artifactid>
          <version>6.1.2</version>
      </dependency>
      <dependency>
          <groupid>log4j</groupid>
          <artifactid>log4j</artifactid>
          <version>1.2.17</version>
      </dependency>
      <dependency>
          <groupid>org.mybatis</groupid>
          <artifactid>mybatis</artifactid>
          <version>3.5.9</version>
      </dependency>
  </dependencies>
  <build>
    <finalname>ithiema_mybatis_quick</finalname>
  </build>
</project>

2.创建user链接

3.编写user实体类

package com.itheima.domain;
public class user {
    private int id;
    private string username;
    private string password;
    public int getid() {
        return id;
    }
    public void setid(int id) {
        this.id = id;
    }
    public string getusername() {
        return username;
    }
    public void setusername(string username) {
        this.username = username;
    }
    public string getpassword() {
        return password;
    }
    public void setpassword(string password) {
        this.password = password;
    }
    @override
    public string tostring() {
        return "user{" +
                "id=" + id +
                ", name='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

4.编写映射文件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">
<!--为什么要给命名空间？当前这个usermapper。xml还会写很多sql语句，调用时候，使用命名空间点方法id-->
<mapper namespace="usermapper">
    <select id="findall" resulttype="com.itheima.domain.user">
        select * from user
    </select>
</mapper>

5.编写核心文件sqlmapconfig.xml

<?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>
<!--    配置数据源的环境-->
    <environments default="development">
        <environment id="development">
            <transactionmanager type="jdbc"></transactionmanager>
            <datasource type="pooled">
                <property name="driver" value="com.mysql.cj.jdbc.driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/dbstudy?servertimezone=asia/shanghai&usessl=false"/>
                <property name="username" value="root"/>
                <property name="password" value="admin"/>
            </datasource>
        </environment>
    </environments>
<!--    加载映射文件-->
    <mappers>
        <mapper resource="com.itheima.mapper/usermapper.xml"></mapper>
    </mappers>
</configuration>

6.编写测试类

import com.itheima.domain.user;
import org.apache.ibatis.session.sqlsession;
import org.apache.ibatis.session.sqlsessionfactory;
import org.apache.ibatis.session.sqlsessionfactorybuilder;
import org.junit.jupiter.api.test;
import org.apache.ibatis.io.resources;
import java.io.inputstream;
import java.util.list;
public class mybatistest {
    @test
    public void test1()throws exception{
//        获得核心配置文件
        inputstream resourceasstream = resources.getresourceasstream("sqlmapconfig.xml");
//2.获得sqlsession工厂对象
        sqlsessionfactory sqlsessionfactory = new sqlsessionfactorybuilder().build(resourceasstream);
//3.获得sqlsession回话对象
        sqlsession sqlsession = sqlsessionfactory.opensession();
//4.执行sql语句 参数：namespace+id
        list<user> userlist = sqlsession.selectlist("usermapper.findall");
//5.打印结果
        system.out.println(userlist);
//6.释放资源
        sqlsession.close();
    }
}

二、映射文件概述

三、增删改查操作

3.1 增加

<!--为什么要给命名空间？当前这个usermapper。xml还会写很多sql语句，调用时候，使用命名空间点方法id-->
<mapper namespace="usermapper">
    <insert id="save" parametertype="com.itheima.domain.user">
     insert into user values(#{id},#{username},#{password})
    </insert>
</mapper>

import com.itheima.domain.user;
import org.apache.ibatis.session.sqlsession;
import org.apache.ibatis.session.sqlsessionfactory;
import org.apache.ibatis.session.sqlsessionfactorybuilder;
import org.junit.jupiter.api.test;
import org.apache.ibatis.io.resources;
import java.io.inputstream;
import java.util.list;
public class mybatistest {
    @test
    public void test1()throws exception{
        user user = new user();
        user.setusername("tom");
        user.setpassword("123456");
        //        获得核心配置文件
        inputstream resourceasstream = resources.getresourceasstream("sqlmapconfig.xml");
//2.获得sqlsession工厂对象
        sqlsessionfactory sqlsessionfactory = new sqlsessionfactorybuilder().build(resourceasstream);
//3.获得sqlsession回话对象
        sqlsession sqlsession = sqlsessionfactory.opensession();
//4.执行sql语句 参数：namespace+id
        sqlsession.insert("usermapper.save",user);
//        mybatis的事务默认是不进行提交的
        sqlsession.commit();
//6.释放资源
        sqlsession.close();
}
}

3.2 修改

<!--为什么要给命名空间？当前这个usermapper。xml还会写很多sql语句，调用时候，使用命名空间点方法id-->
<mapper namespace="usermapper">
       <update id="update" parametertype="com.itheima.domain.user">
        update user set username=#{username},password=#{password} where id=#{id}
    </update>
</mapper>

import com.itheima.domain.user;
import org.apache.ibatis.session.sqlsession;
import org.apache.ibatis.session.sqlsessionfactory;
import org.apache.ibatis.session.sqlsessionfactorybuilder;
import org.junit.jupiter.api.test;
import org.apache.ibatis.io.resources;
import java.io.inputstream;
import java.util.list;
public class mybatistest {
    @test
    public void test1()throws exception{
//      修改
        user user = new user();
        user.setid(5);
        user.setusername("lucy");
        user.setpassword("123456");
        //获得核心配置文件
        inputstream resourceasstream = resources.getresourceasstream("sqlmapconfig.xml");
//2.获得sqlsession工厂对象
        sqlsessionfactory sqlsessionfactory = new sqlsessionfactorybuilder().build(resourceasstream);
//3.获得sqlsession回话对象
        sqlsession sqlsession = sqlsessionfactory.opensession();
//4.执行sql语句 参数：namespace+id
        sqlsession.update("usermapper.update",user);
//        mybatis的事务默认是不进行提交的
        sqlsession.commit();
//6.释放资源
        sqlsession.close();
    }
}

3.3删除

//      删除
        //获得核心配置文件
        inputstream resourceasstream = resources.getresourceasstream("sqlmapconfig.xml");
//2.获得sqlsession工厂对象
        sqlsessionfactory sqlsessionfactory = new sqlsessionfactorybuilder().build(resourceasstream);
//3.获得sqlsession回话对象
        sqlsession sqlsession = sqlsessionfactory.opensession();
//4.执行sql语句 参数：namespace+id
        sqlsession.delete("usermapper.delete",1);
//        mybatis的事务默认是不进行提交的
        sqlsession.commit();
//6.释放资源
        sqlsession.close();

<!--为什么要给命名空间？当前这个usermapper。xml还会写很多sql语句，调用时候，使用命名空间点方法id-->
<mapper namespace="usermapper">
    <delete id="delete" parametertype="java.lang.integer">
        delete from user where id=#{id}
    </delete>
</mapper>