MyBatis简单使用的demo
MyBatis 是一个java持久层框架,类似hibernate,但是比hibernate轻,功能没hibernate多,关于谁好谁坏,一直有人再争论,应该是各有各的好处,大家可以自行百度其优缺点。
本章内容
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- MyBatis 配置
-
- MyBatis Java dome
MyBatis 配置
- -下载MyBatis包,推荐使用maven下载
-
-下载MySql包,推荐使用maven下载
<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.31</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.1.1</version> </dependency>
MyBatis 使用
1: 建一个xml配置文件,配置数据库连接
<?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>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<!-- 配置数据库连接信息 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/test" />
<property name="username" value="root" />
<property name="password" value="xxx" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/company/userMapper.xml"/>
</mappers>
</configuration>
2:建立一个pojo User类
package com.company;
/**
* Created by zteliuyw on 15/7/6.
*/
public class User {
private int id;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
3:建立一个user方法对于的映射文件mapping
<?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.company.UserMapper">
<!--
根据id查询得到一个user对象
-->
<select id="getUser" parameterType="int"
resultType="com.company.User">
select * from user where id=#{id}
</select>
</mapper>
4:建立一个映射文件mapping对应方法的类
package com.company;
public interface UserMapper {
public User getUser(int id);
}
5:使用mybatis获取数据
public class Main {
public static void main(String[] args) throws IOException {
//mybatis的配置文件
String resource = "conf.xml";
//使用类加载器加载mybatis的配置文件(它也加载关联的映射文件)
InputStream is = Main.class.getClassLoader().getResourceAsStream(resource);
//构建sqlSession的工厂
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
//使用MyBatis提供的Resources类加载mybatis的配置文件(它也加载关联的映射文件)
//Reader reader = Resources.getResourceAsReader(resource);
//构建sqlSession的工厂
//SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
//创建能执行映射文件中sql的sqlSession
SqlSession session = sessionFactory.openSession();
/**
* 映射sql的标识字符串,
* me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值,
* getUser是select标签的id属性值,通过select标签的id属性值就可以找到要执行的SQL
*/
String statement = "com.company.User.getUser";//映射sql的标识字符串
UserMapper userMapper = session.getMapper(UserMapper.class);
//执行查询返回一个唯一user对象的sql
User user = userMapper.getUser(1);
System.out.println(user);
session.close();
}
}
输出的结果: {“id”:1,name:”liuyanwei”}