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  • mybatis 入门学习

    所须要jar包:mybatis-3.x.x.jar 、假设须要和spring整合,还须要增加相关的包

    1:看项目文件夹 红颜色不要关心

    2:依照步骤:

    1:增加jar包

    2:创建数据源(configuration.xml)创建数据库(此处省略)

    <?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> <!--给实体类起一个别名 user --> <typeAlias type="com.forum.po.User" alias="User" /> </typeAliases> <!--数据源配置 这块用 mysql数据库 --> <environments default="development"> <environment id="development"> <transactionManager type="jdbc" /> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/test" /> <property name="username" value="test" /> <property name="password" value="test" /> </dataSource> </environment> </environments> <mappers> <!--userMapper.xml装载进来 同等于把“dao”的实现装载进来 --> <mapper resource="myBatis/userMapper.xml" /> </mappers> </configuration>


    3:创建实体类USER
    package com.forum.po;
    
    /**
     * 用户类
     * 
     */
    public class User extends Entity {
    	private String name;
    	private Integer age;
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    	public User() {
    	}
    
    }

    4:创建dao接口、能够说是Mapper接口:UserMapper
    package com.forum.dao;
    
    import com.forum.po.User;
    
    public interface UserMapper {
    	public User findById(String Id);
    }
    

    5:创建dao的实现,不同于hibernarte的此处的实现为一个xml文件,也就是userMapper.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"> <!--这块等于dao接口的实现 namespace必须和接口的类路径一样--> <mapper namespace="com.forum.dao.UserMapper"> <!-- findById必须和接口中的方法名一样 返回一个User 就是刚才的别名 假设不弄别名要连类路径一起写 麻烦--> <select id="findById" parameterType="HashMap" resultType="User"> select * from butone.student where id=#{id} </select> </mapper>


    6:測试类,MyBatisTest
    package com.forum.test;
    
    import java.io.IOException;
    
    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 com.forum.dao.UserMapper;
    import com.forum.po.User;
    
    /**
     * myBatis数据库连接測试
     * 
     * @author db2admin
     * 
     */
    public class MyBatisTest {
    	/**
    	 * 获得MyBatis SqlSessionFactory  
    	 * SqlSessionFactory负责创建SqlSession,一旦创建成功,就能够用SqlSession实例来运行映射语句,commit,rollback,close等方法。
    	 * @return
    	 */
    	private static SqlSessionFactory getSessionFactory() {
    		SqlSessionFactory sessionFactory = null;
    		String resource = "configuration.xml";
    		try {
    			sessionFactory = new SqlSessionFactoryBuilder().build(Resources
    					.getResourceAsReader(resource));
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		return sessionFactory;
    	}
    
    	public static void main(String[] args) {
    		SqlSession sqlSession = getSessionFactory().openSession();
    		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    		User user = userMapper.findById("1");
    		System.out.println(user.getName());
    
    	}
    
    }

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  • 原文地址:https://www.cnblogs.com/wzzkaifa/p/6774222.html
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