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MyBatis
快速入门#xf…前言
公司要求没办法前端也要了解一下后端知识这里记录一下自己的学习
学习教程黑马mybatis教程全套视频教程2天Mybatis框架从入门到精通
文档 https://mybatis.net.cn/index.html
MyBatis
快速入门查询user表中所有数据
创建user表添加数据创建模块导入坐标编写mybatis核心配置文件 ----替换连接信息解决硬编码问题编写sql映射文件— 统一管理sql语句解决硬编码问题编码 定义POJO类对应数据库的表加载核心配置文件获取SqlSessionFactory对象获取SQLSession对象执行sql语句释放资源
创建模块
创建模块 File - New - Module 导入坐标 pom.xml
dependencies!--mybatis依赖--dependencygroupIdorg.mybatis/groupIdartifactIdmybatis/artifactIdversion3.5.9/version/dependency!--mysql驱动依赖--dependencygroupIdmysql/groupIdartifactIdmysql-connector-java/artifactIdversion8.0.31/version/dependency!-- junit 单元测试 --dependencygroupIdjunit/groupIdartifactIdjunit/artifactIdversion4.13.2/versionscopetest/scope/dependency!-- slf4j 日志 --dependencygroupIdorg.slf4j/groupIdartifactIdslf4j-api/artifactIdversion1.7.30/version/dependency!-- logback 日志 --dependencygroupIdch.qos.logback/groupIdartifactIdlogback-classic/artifactIdversion1.2.3/version/dependencydependencygroupIdch.qos.logback/groupIdartifactIdlogback-core/artifactIdversion1.2.3/version/dependency/dependenciessrc/main/resources/logback.xml ?xml version1.0 encodingUTF-8?
configuration!-- console表示当前日志信息是可以输出到控制台的--appender nameConsole classch.qos.logback.core.ConsoleAppenderencoderpattern【%level】 %cyan(【%thread】) %boldGreen(%logger{15}) - %msg %n/pattern/encoder/appenderlogger namecom.Carter_x levelDEBUG additivityfalseappender-ref refConsole//logger
/configuration核心配置文件 src/main/resources/mybatis-config.xml
?xml version1.0 encodingUTF-8 ?
!DOCTYPE configurationPUBLIC -//mybatis.org//DTD Config 3.0//ENhttp://mybatis.org/dtd/mybatis-3-config.dtd
configurationenvironments defaultdevelopmentenvironment iddevelopmenttransactionManager typeJDBC/dataSource typePOOLED!-- 数据库连接信息--property namedriver valuecom.mysql.cj.jdbc.Driver/property nameurl valuejdbc:mysql://localhost:3306/test/property nameusername valueroot/property namepassword value123456//dataSource/environment/environmentsmappersmapper resourceorg/mybatis/example/BlogMapper.xml//mappers
/configurationsql映射文件 src/main/resources/UserMapper.xml表示是来操作user表的sql映射文件
?xml version1.0 encodingUTF-8 ?
!DOCTYPE mapperPUBLIC -//mybatis.org//DTD Mapper 3.0//ENhttp://mybatis.org/dtd/mybatis-3-mapper.dtd!--
namespace: 命名空间
resultType:返回值的类型一般是实体类
id:唯一标识
--
mapper namespacetestselect idselectAllUser resultTypecom.example.pojo.Userselect * from user;/select
/mapper在src/main/java下创建对于的实体类
package com.example.pojo;public class User {
}修改mybatis-config.xml文件指定刚才创建的sql映射文件
mappers!-- 加载sql映射文件--mapper resourceuserMapper.xml/
/mappers编码
修改之前创建的User类类的属性要与对应表里的字段对应
package com.example.pojo;public class User {private Integer id;private String name;private Integer age;private String email;public Integer getId() {return id;}public void setId(Integer id) {this.id id;}public String getName() {return name;}public void setName(String name) {this.name name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age age;}public String getEmail() {return email;}public void setEmail(String email) {this.email email;}Overridepublic String toString() {return User{ id id , name name \ , age age , email email \ };}}编写测试类
编写一个测试类用于测试代码
package org.example;import java.io.IOException;
import java.io.InputStream;
import java.util.List;import com.example.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class Main {public static void main(String[] args) throws IOException {// 1、加载mybatis的核心配置文件获取SqlSessionFactory对象下面的是从官网复制的String resource mybatis-config.xml;InputStream inputStream Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory new SqlSessionFactoryBuilder().build(inputStream);// 2、获取SqlSession对象SqlSession sqlSession sqlSessionFactory.openSession();// 3、执行sql语句查询所有数据// 指定要执行的sql语句这里传入对应的标识对应UserMapper.xml文件中select idselectAllUser resultTypeUserListUser userList sqlSession.selectList(test.selectAllUser);System.out.println(userList);System.out.println(数据总条数 userList.size());// 4、关闭资源sqlSession.close();}
}执行结果
