【Mybatis】使用IDEA创建第一个Mybatis入门程序

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前言

       本文介绍了本人在学习Mybatis时使用IntelliJ IDEA创建的第一个Mybatis入门程序，程序主要实现了对用户表中的信息进行增删改查操作。

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1、搭建环境

项目结构

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1.1 搭建数据库

CREATE TABLE `user`  (
  `id` int(0) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `pwd` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
)

INSERT INTO `user`(`name`, `pwd`) VALUES ('CSDN', '123456')
INSERT INTO `user`(`name`, `pwd`) VALUES ('C搜索', '123456')
INSERT INTO `user`(`name`, `pwd`) VALUES ('慢热型网友', '123456')

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1.2 新建项目

1. 新建一个普通maven项目
2. 删除src目录
3. 导入maven依赖->父工程的pom.xml

<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>

    <groupId>org.examplegroupId>
    <artifactId>mybatistestartifactId>
    <packaging>pompackaging>
    <version>1.0-SNAPSHOTversion>
    <modules>
        <module>mybatismodule>
    modules>

    <properties>
        <maven.compiler.source>8maven.compiler.source>
        <maven.compiler.target>8maven.compiler.target>
    properties>

    
    <dependencies>
        <dependency>
            
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.47version>
        dependency>
        
        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.2version>
        dependency>

        
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
        dependency>
    dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <includes>
                    <include>**/*.propertiesinclude>
                    <include>**/*.xmlinclude>
                includes>
                <filtering>truefiltering>
            resource>
            <resource>
                <directory>src/main/javadirectory>
                <includes>
                    <include>**/*.propertiesinclude>
                    <include>**/*.xmlinclude>
                includes>
                <filtering>truefiltering>
            resource>
        resources>
    build>


project>
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1.3 创建一个模块

1. 在父工程下创建一个子工程
   父工程右击->new->Module->Maven项目
2. 编写mybatis的核心配置文件（）
   在子工程创建mybatis-config.xml

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&useEncoding=false&characterEncoding=UTF-8&serverTimezone=GMT"/>
                
                <property name="username" value="username"/>
                
                <property name="password" value="password"/>
            dataSource>
        environment>
    environments>
    <mappers>
        <mapper resource="com/richard/pojo/UserMapper.xml"/>
    mappers>

configuration>


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3. 编写mybatis的工具类
   创建utils包->创建MybatisUtils.java
   com/richard/utils/MybatisUtils.java

package com.richard.utils;

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;

//sqlSessionFactory用来构建sqlSession
public class MybatisUtils {

    //提升SqlSessionFactory的作用域
    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            // 使用Mybatis第一步获取sqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

      // 既然有了SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
      // SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。
    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();

    }
}

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2、编写代码

2.1 实体类

com/richard/pojo/User.java

package com.richard.pojo;

import lombok.Data;
import java.io.Serializable;

/**
 * (User)实体类
 *
 * @author makejava
 * @since 2022-11-04 14:09:54
 */
//在这里使用了Lombok插件的@Data注解，编写实体类更方便
@Data
public class User implements Serializable {
    private static final long serialVersionUID = -76233651672372585L;
    //用户id
    private Integer id;
    //用户名
    private String name;
   //用户密码
    private String pwd;
    
}


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2.2 接口实现类

com/richard/pojo/UserMapper.xml

DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.richard.pojo.User">

    
    <select id="UserList" resultType="com.richard.pojo.User">
        select * from user
    select>
    
    
    <select id="findUserById" parameterType="Integer" resultType="com.richard.pojo.User">
        select *
        from user
        where id = #{id};
    select>
    
    
    <select id="findUserByName" parameterType="String" resultType="com.richard.pojo.User">
        --         select * from user where name like '%${value}%'
        select *
        from user
        where name like concat('%', #{name}, '%')
    select>
    
    
    <insert id="addUser" parameterType="com.richard.pojo.User">
        insert into user(id, name, pwd)
        values (#{id}, #{name}, #{pwd})
    insert>
    
    
    <update id="updateUser" parameterType="com.richard.pojo.User">
        update user
        set id=#{id},
            name=#{name},
            pwd=#{pwd}
        where id = #{id}
    update>
    
    
    <delete id="deleteUserById" parameterType="Integer">
        delete
        from user
        where id = #{id}
    delete>
mapper>


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2.3 测试类

src/test/java/com/richard/pojo/UserTest.java

package com.richard.pojo;

import com.richard.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserTest {
    @Test
    public void UserList(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        List<User> users = sqlSession.selectList("UserList");
        for (User user : users) {
            System.out.println(user);
        }
        sqlSession.close();

    }
    @Test
    public void userFindByIdTest() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        User user = sqlSession.selectOne("findUserById", 1);
        System.out.println(user.toString());
        sqlSession.close();
    }

    @Test
    public void userFindByNameTest() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        List<User> users = sqlSession.selectList("findUserByName", "C");
        for (User user : users) {
            System.out.println(user);
        }
        sqlSession.close();
    }

    @Test
    public void addUserTest() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //创建User对象
        User user = new User();
        user.setId(4);
        user.setName("add测试");
        user.setPwd("123456");
        //执行sqlsession
        int rows = sqlSession.insert("addUser", user);
        if (rows > 0) {
            System.out.println("您成功添加了" + rows + "插入了一条数据");
        } else {
            System.out.println("插入失败！！！");
        }
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void updateUserTest() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //创建User对象
        User user = new User();
        user.setId(4);
        user.setName("add测试123");
        user.setPwd("修改密码");
        //执行sqlsession
        int rows = sqlSession.insert("updateUser", user);
        if (rows > 0) {
            System.out.println("您成功修改了" + rows + "条数据");
        } else {
            System.out.println("修改失败！！！");
        }
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void deleteUserTest() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //执行sqlsession
        int rows = sqlSession.insert("deleteUserById", 4);
        if (rows > 0) {
            System.out.println("您成功删除了" + rows + "条数据");
        } else {
            System.out.println("删除失败！！！");
        }
        sqlSession.commit();
        sqlSession.close();
    }
}

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测试截图

查询User表中所有用户信息

根据用户id获取用户信息

根据用户姓名模糊查询用户信息

增加用户

修改用户

删除用户