前置环境
创建数据库表并添加数据:
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` int(11) NOT NULL auto_increment,
`username` varchar(32) NOT NULL COMMENT '用户名称',
`birthday` datetime default NULL COMMENT '生日',
`sex` char(1) default NULL COMMENT '性别',
`address` varchar(256) default NULL COMMENT '地址',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into `user`(`id`,`username`,`birthday`,`sex`,`address`) values
(41,'老王','2018-02-27 17:47:08','男','北京'),
(42,'小二王','2018-03-02 15:09:37','女','北京金燕龙'),
(43,'小二王','2018-03-04 11:34:34','女','北京金燕龙'),
(45,'传智播客','2018-03-04 12:04:06','男','北京金燕龙'),
(46,'老王','2018-03-07 17:37:26','男','北京'),
(48,'小马宝莉','2018-03-08 11:44:00','女','北京修正');
项目结构

配置文件
[db.properties]driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://192.168.91.1:3306/test?useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true
username=root
password=123456
[mybatis.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>
<properties resource="db.properties"/>
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>
<typeAliases>
<package name="com.rhett.domain"></package>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="{driver}"/>
<property name="url" value="{url}"/>
<property name="username" value="{username}"/>
<property name="password" value="{password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/rhett/dao/IUserDao.xml"/>
</mappers>
</configuration>
添加JavaBean
在domain下编写bean:
package com.rhett.domain;
import java.io.Serializable;
import java.util.Date;
public class User implements Serializable {
private Integer id;
private String username;
private Date birthday;
private String sex;
private String address;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User [id=" + id + ", username=" + username + ", birthday=" + birthday
+ ", sex=" + sex + ", address="
+ address + "]";
}
}
编写Mapper
首先编写接口类IuserDao:
package com.rhett.dao;
import com.rhett.domain.User;
import org.apache.ibatis.annotations.Select;
import java.util.List;
public interface IUserDao {
/**
* 查询所有操作
*/
List<User> findAll();
}
然后在resources和包对应的相同文件夹下编写mapper的xml配置(IUserDao.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">
<mapper namespace="com.rhett.dao.IUserDao">
<!-- 配置查询所有操作 -->
<select id="findAll" resultType="User">
select * from user
</select>
</mapper>
然后在mybatis.xml文件中配置mapper(见上面的配置,我用了包扫描)
编写测试类
package test;
import com.rhett.dao.IUserDao;
import com.rhett.domain.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 java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class MybatisTest {
public static void main(String[] args) throws IOException {
// 1.读取配置文件
InputStream in = Resources.getResourceAsStream("mybatis.xml");
// 2.创建SqlSessionFactory工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
// 3.使用工厂生成SqlSession对象
SqlSession session = factory.openSession();
// 4.使用SqlSession创建Dao接口的代理
IUserDao userDao = session.getMapper(IUserDao.class);
// 5.使用代理对象执行方法
List<User> users = userDao.findAll();
for(User user:users){
System.out.println(user);
}
// 6.释放资源
session.close();
in.close();
}
}
输出:
User [id=41, username=老王, birthday=Wed Feb 28 07:47:08 CST 2018, sex=男, address=北京]
User [id=42, username=小二王, birthday=Sat Mar 03 05:09:37 CST 2018, sex=女, address=北京金燕龙]
User [id=43, username=小二王, birthday=Mon Mar 05 01:34:34 CST 2018, sex=女, address=北京金燕龙]
User [id=45, username=传智播客, birthday=Mon Mar 05 02:04:06 CST 2018, sex=男, address=北京金燕龙]
User [id=46, username=老王, birthday=Thu Mar 08 07:37:26 CST 2018, sex=男, address=北京]
User [id=48, username=小马宝莉, birthday=Fri Mar 09 01:44:00 CST 2018, sex=女, address=北京修正]
补充:基于注解的修改方法
在编写接口的时候加上注解:
public interface IUserDao {
/*
* 查询所有用户
*/
@Select("select * from user")
List<User> findAll();
}
然后修改mybatis.xml
<!-- 告知 mybatis 映射配置的位置 -->
<mappers>
<mapper class="com.itheima.dao.IUserDao"/>
</mappers>
就可以不用IUserDao.xml了。
原创文章,作者:彭晨涛,如若转载,请注明出处:https://www.codetool.top/article/mybatis%e4%bd%bf%e7%94%a8%e4%b8%8e%e5%85%a5%e9%97%a8%e6%a1%88%e4%be%8b/