配置pom配置文件
首先在pom配置文件中添加mysql以及mybatis依赖,此处mysql依赖尽量与后续添加可视化数据库源所用的mysql驱动版本保持一致
<!--mybatis依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.6</version>
</dependency>
<!--mysql依赖-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.29</version>
</dependency>
之后添加资源文件指定
<build>
<resources>
<!--java目录-->
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
</resource>
<!--resource目录-->
<resource>
<directory>src/main/resource</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
</resource>
</resources>
</build>
添加jdbc.properties属性配置文件
在resource目录下添加jdbc属性配置文件
jdbc.driverClassName=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/qinsijun?userUnicode=true&character=utf-8
jdbc.username=root
jdbc.password=admin
创建查询实体类
实体类的属性需与所查询字段保持一致,如有自增字段构造方法须设置两个,全参构造方法和缺少自增字段属性的构造方法
package com.thugstyle.pojo;
public class Student {
private Integer id;
private String lojinName;
private String lojinPwd;
private String realName;
public Student(Integer id, String lojinName, String lojinPwd, String realName) {
this.id = id;
this.lojinName = lojinName;
this.lojinPwd = lojinPwd;
this.realName = realName;
}
public Student(String lojinName, String lojinPwd, String realName) {
this.lojinName = lojinName;
this.lojinPwd = lojinPwd;
this.realName = realName;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLojinName() {
return lojinName;
}
public void setLojinName(String lojinName) {
this.lojinName = lojinName;
}
public String getLojinPwd() {
return lojinPwd;
}
public void setLojinPwd(String lojinPwd) {
this.lojinPwd = lojinPwd;
}
public String getRealName() {
return realName;
}
public void setRealName(String realName) {
this.realName = realName;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", lojinName='" + lojinName + '\'' +
", lojinPwd='" + lojinPwd + '\'' +
", realName='" + realName + '\'' +
'}';
}
}
配置StudentMapper.xml配置文件
<?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是整个文件的大标签,用来开始和结束xml文件-->
<!--namespace指定命名空间,相当于包名,用来区分不同mapper.xml文件中相同的id属性-->
<mapper namespace="qsj">
<select id="getAll" resultType="com.thugstyle.pojo.Student">
/*resultType指定查询返回的结果类型,如果是集合,则必须是泛型类型
parameterType如果有参数,则必须通过他来指定参数的类型*/
select id,lojinName,lojinPwd,realName from t_user
</select>
</mapper>
配置 SqlMapConfig.xml核心配置文件
<?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">
<!--头部配置粘贴-->
<configuration>
<!-- 第一步:读取jdbc属性配置文件-->
<properties resource="jdbc.properties"></properties>
<!--第二步:配置数据库环境变量,数据库连接配置-->
<environments default="development">
<!--开发时在公司使用的数据库配置-->
<environment id="development">
<!--id就是environments的default属性使用的-->
<!--配置事务管理器,可通过查询mybatis源码包了解事务管理方式-->
<!-- type:指定事务管理的方式
JDBC:事务的控制交给程序员处理
MANAGED:由容器(Spring)管理事务-->
<transactionManager type="JDBC"></transactionManager>
<!--配置数据源-->
<!-- type:指定不同的配置方式
JNDI:java命名目录接口,在服务器端进行数据库连接池的管理
POOLED:使用数据库连接池
UNPOOLED:不使用数据库连接池-->
<dataSource type="POOLED">
<!--配置数据库连接的基本参数-->
<property name="driver" value="${jdbc.driverClassName}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!--注册mapper.xml文件-->
<mappers>
<mapper resource="StudentMapper.xml"></mapper>
<!--resource:通过resource目录下指定名称的文件注册
url:使用绝对路径注册
class:动态代理方式注册-->
</mappers>
</configuration>
创建测试类完成查询
package com.thugstyle;
import com.thugstyle.pojo.Student;
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 org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class MyTest {
@Test
public void TestMybatis() throws IOException {
/* 使用文件流读取核心配置文件SqlMapConfig.xml*/
InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
/*创建SqlSessionFactory工厂*/
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
/*取出SqlSession对象*/
SqlSession sqlSession = factory.openSession();
/*完成查询操作*/
List<Student> list = sqlSession.selectList("qsj.getAll");
list.forEach(student -> System.out.println(student));
/*关闭sqlSession*/
sqlSession.close();
}
}