作为一个java菜鸟，早就从慕课网中学到一些基本的mybatis的用法，但是一直不成体系，懵懵懂懂，既然正式入了java这个坑，就打算好好学学，所以买了本《MyBatis从入门到精通》，在此记录下学习的点滴。
数据库版本：Server version: 8.0.15 MySQL Community Server - GPL
数据准备：
先写一个最简单的查询
1、新建一个空白的maven项目，引入相关依赖包
<dependencies>
<!--测试需要-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!--mybatis-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version></version>
</dependency>
<!--数据库连接驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version></version>
</dependency>
</dependencies>
2、在resources中添加mybatis的配置文件mybatis-config.xml
这里选用最基本的jdbc事务管理器，不用数据库连接池。此处因为mysql的版本原因，要禁用SSL。同时配置数据库实体的位置和mapper文件路径。
<?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>
<typeAliases>
<package name="com.forest.owl.entity"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC">
<property name="" value=""/>
</transactionManager>
<dataSource type="UNPOOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/forest?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper/UserMapper.xml" />
</mappers>
</configuration>
2、编辑数据库实体User
package com.forest.owl.entity;
import java.util.Date;
public class User {
private int id;
private String account;
private String passwd;
private String nickname;
private String phone;
private String email;
private Date createTime;
private Date updateTime;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
public String getPasswd() {
return passwd;
}
public void setPasswd(String passwd) {
this.passwd = passwd;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
public Date getUpdateTime() {
return updateTime;
}
public void setUpdateTime(Date updateTime) {
this.updateTime = updateTime;
}
}
3、在resources中添加mapper文件夹，在该文件夹中添加UserMapper.xml文件
mapper文件的命名空间是必须的，这里是随便命名，暂且还不清楚该属性的具体作用。
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="mapper">
<select id="selectUsers" resultType="com.forest.owl.entity.User">
SELECT id, account, passwd, nickname, phone, email, create_time as createTime, update_time as updateTime
FROM user
</select>
</mapper>
4、编写测试类
import com.forest.owl.entity.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;
import org.junit.BeforeClass;
import org.junit.Test;
import java.io.IOException;
import java.io.Reader;
import java.util.List;
public class TestUserMapper {
private static SqlSessionFactory sqlSessionFactory;
@BeforeClass
public static void init(){
try {
Reader reader = Resources.getResourceAsReader("mybatis.config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
@Test
public void TestMybatis(){
SqlSession sqlSession = sqlSessionFactory.openSession();
List<User> userList = sqlSession.selectList("selectUsers");
System.out.println(userList.size());
System.out.println(userList.get(0).getNickname());
System.out.println(userList.get(0).getCreateTime());
}
}
测试结果：