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Mybatis 入门(用.xml 的方式)

海牙秋天 2022-03-12 阅读 122

1、SqlMapConfig.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">
<!--mybatis的主配置文件-->
<configuration>
<!-- 配置环境-->
<environments default="mysql"><!-- 默认值,可以随便起,但是下面id值要和这个一样 -->
<!-- 配置mysql的环境-->
<environment id="mysql">
<!-- 配置事务的类型-->
<transactionManager type="JDBC"></transactionManager>
<!-- 配置数据源(连接池)-->
<dataSource type="POOLED">
<!-- 配置连接数据库的4个基本信息-->
<property name="driver" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis"></property>
<property name="username" value="root"></property>
<property name="password" value="123456"></property>
</dataSource>
</environment>
</environments>
<!-- 指定映射配置文件的位置,映射配置文件是指每个dao独立的配置文件-->
<mappers>
<mapper resource="com/itheima/dao/IUserDao.xml"/>
</mappers>
</configuration>

2、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.itheima.dao.IUserDao"><!-- dao的权限定类名 -->
<!-- 配置查询所有-->
<select id="findAll" resultType="com.itheima.domain.User">
select * from user
</select>
</mapper>

3、mybatisTest.java 测试类:

package com.itheima.test;
import com.itheima.dao.IUserDao;
import com.itheima.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.InputStream;
import java.util.List;

public class MybatisTest {
public static void main(String[] args) throws Exception {
//读取配置文件
InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//创建SqlSessionFactory工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
//使用工厂创建SqlSession对象
SqlSession session = factory.openSession();
//使用SqlSession创建Dao接口的代理对象
IUserDao userDao = session.getMapper(IUserDao.class);
//使用代理对象执行方法
List<User> users = userDao.findAll();
for(User user:users){
System.out.println(user);
}
//释放资源
session.close();
in.close();

}
}

4、IUserDao.java :

package com.itheima.dao;

import com.itheima.domain.User;

import java.util.List;

//用户的持久层接口
public interface IUserDao {
List<User> findAll();
}

5、user.java :

package com.itheima.domain;

import java.io.Serializable;

public class User implements Serializable {//实现Serializable的目的可能是字符串序列
private Integer id;
private String username;
private String birthday;
private String sex;
private String address;

@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", birthday='" + birthday + '\'' +
", sex='" + sex + '\'' +
", address='" + 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 String getBirthday() {
return birthday;
}

public void setBirthday(String 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;
}
}
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