1.MyBatis入门示例

MyBatis:
ibatis:apache
2010 ibatis-> google colde ,Mybatis

MyBatis可以简化JDBC操作，实现数据的持久化。
ORM:Object Relational Mapping
person对象 person表

ORM：概念，
Mybatis是ORM的一个实现/Hibernate
orm可以使得开发人员像操作对象一样操作数据库表。

开发mybatis程序从步骤：
1.配置mybatis
conf.xml:配置数据库信息和需要加载的映射文件
2 表 - 类
映射文件xxMapper.xml :增删改查标签<select>
3 测试类：
session.selectOne("需要查询的SQL的namespace.id","SQL的参数值");

示例：

Student .java

public class Student {
	private int id;
	private String name;
	private int age ;	
	public Student() {
	}
	public Student(int id, String name, int age) {
		this.id = id;
		this.name = name;
		this.age = age;
	}
	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;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	} 	
	@Override
	public String toString() {
		return this.id+","+this.name+","+this.age ;
	}
}

personMapper.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="org.lanqiao.entity.personMapper"> <!--文件的路径名字-->
	<select id="queryPersonById" resultType="org.lanqiao.entity.Person"  parameterType="int">
		select * from person where  id = #{id} 
	</select>	
</mapper>

conf.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>
	<environments default="development">
		<environment id="development">
		<transactionManager type="JDBC"/>
			<dataSource type="POOLED">
			<!-- 配置数据库信息 -->
			<property name="driver" value="oracle.jdbc.OracleDriver"/>
			<property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:ORCL"/>
			<property name="username" value="scott"/>
			<property name="password" value="tiger"/>
		</dataSource>
		</environment>
	</environments>
	<mappers>
		<!-- 加载映射文件 -->
		<mapper resource="org/lanqiao/entity/personMapper.xml"/>
	</mappers>
</configuration>

TestMyBatis.java

public class TestMyBatis {
	public static void main(String[] args) throws IOException {
	//加载MyBatis配置文件（为了访问数据库）
	Reader reader = Resources.getResourceAsReader("conf.xml") ;
	SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader) ;
	//session - connection		

	SqlSession session = sessionFactory.openSession() ;
	String statement = "org.lanqiao.entity.personMapper.queryPersonById" ;<!--namespace+Id-->
	Student person = session.selectOne( statement,1 ) ;<!--1是输入参数-->
	System.out.println(person);
	session.close(); 		
   }
}

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