MyBatis 初探

话说很早以前就知道ibatis是一个ORM—对象关系映射框架，以前一直使用的是hibernate，所以也没去实际感受一下他的魅力之所在~~现在有个项目用到了MyBatis，所以就特来感受一番。
@@需要准备的jar包：mybatis-3.0.5.jar和sqljdbc.jar

下面开始我们的项目：
1、第一步：建立数据库studentDB，建表StudentInfo，具体的建表语句就不写了，比较简单。
2、第二步：创建工程

3、第三步：导入jar包（mybatis-3.0.5.jar和sqljdbc.jar）

4、第四步：编写MyBatis主配置文件—可以自定义名字。我在这里延续ibatis的传统使用SqlMapConfig.xml（类似于hibernate中的hibernate.cfg.xml文件），具体代码如下：

<?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>
		<typeAlias type="com.up.StudentInfo" alias="StudentInfo"/>
	</typeAliases>
	<environments default="development"> 
		<environment id="development"> 
			<transactionManager type="JDBC"/> 
				<dataSource type="POOLED"> 
					<property name="driver" value="com.microsoft.sqlserver.jdbc.SQLServerDriver"/> 
					<property name="url" value="jdbc:sqlserver://localhost:1433;databasename=studentDB"/> 
					<property name="username" value="sa"/> 
					<property name="password" value="123456"/> 
				</dataSource> 
		</environment> 
	</environments> 
	<mappers> 
		<mapper resource="studentMapper.xml"/> 
	</mappers> 
</configuration> 

5、第五步：配置数据库表映射文件：studentMapper.xml（类似于hiberante中的.hbm.xml文件）

<?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">	
<!--这里namespace必须配置为StudentMapper接口的路径，否则运行时会报“is not known to the MapperRegistry”
-->
<mapper namespace="com.up.StudentMapper">
     <!-- 这里必须配置resultMap，否则在selectBoy中，将报null错误，无法将数据库中的值注入到StudentInfo类中-->
      <resultMap type="StudentInfo" id="boys">
		<id property="stuid" column="stuid"/>
		<result property="stuname" column="stuname" />
		<result property="stusex" column="stusex" />
		<result property="stuscore" column="stuscore" />
		<result property="stuage" column="stuage" />
	</resultMap>
	<select id="selectBoy" parameterType="string" resultMap="boys" resultType="arraylist">
		select * from StudentInfo where stusex = #{stusex}
	</select>
        <!--这里的id必须配置和StudentMapper中的方法一样，否则也会报错。下面也一样道理-->
        <select id="selectByID" parameterType="int" resultType="StudentInfo">
		select * from StudentInfo where stuid = #{stuid} 
	</select>
	<insert id="addStudent" parameterType="StudentInfo" useGeneratedKeys="true">
		insert into StudentInfo(stuname,stusex,stuscore,stuage)
		values(#{stuname},#{stusex},#{stuscore},#{stuage})
	</insert>
	<update id="updateStudent" parameterType="StudentInfo">
		update StudentInfo 
			set stuname=#{stuname},stusex=#{stusex},stuscore=#{stuscore}
		where stuid=#{stuid}
	</update>
	<delete id="deleteStudent" parameterType="int">
		delete from StudentInfo where stuid = #{stuid} 
	</delete>
</mapper>

6、第六步：编写java代码

StudentInfo实体类的代码如下：

package com.up;
public class StudentInfo {
	private int stuid;
	private String stuname;
	private String stusex;
	private double stuscore;
	private int stuage;
	public StudentInfo(){
		super();
	}
	public StudentInfo(int stuid,String stuname,String stusex,double stuscore,int stuage){
		super();
		this.stuid = stuid;
		this.stuname = stuname;
		this.stusex = stusex;
		this.stuscore = stuscore;
		this.stuage = stuage;
	}
	public void setStuid(int stuid) {
		this.stuid = stuid;
	}
	public int getStuid() {
		return stuid;
	}
	public int getStuage() {
		return stuage;
	}
	public String getStuname() {
		return stuname;
	}
	public double getStuscore() {
		return stuscore;
	}
	public String getStusex() {
		return stusex;
	}
	public void setStuage(int stuage) {
		this.stuage = stuage;
	}
	public void setStuname(String stuname) {
		this.stuname = stuname;
	}
	public void setStuscore(double stuscore) {
		this.stuscore = stuscore;
	}
	public void setStusex(String stusex) {
		this.stusex = stusex;
	}
	public String toString(){
		return "学号："+this.getStuid()+" 姓名："+this.getStuname()+" 性别："+this.getStusex()+
				" 年龄："+this.getStuage()+" 分数："+this.getStuscore();
	}
}

StudentInfo实体的映射器取名为：StudentMapper(接口)，其代码如下：

package com.up;
import java.util.ArrayList;

public interface StudentMapper {
	//这里的方法对应了studentMapper.xml中的select,update,delete语句
	public ArrayList<StudentInfo> selectBoy(String male); 
	public StudentInfo selectByID(int id);
	public void addStudent(StudentInfo student);
	public void updateStudent(StudentInfo student);
	public void deleteStudent(int id);
}

注意： 该接口类似于hibernate中的dao层接口，只是该接口只需要声明，不需要实现。

据我所知：在MyBatis中不声明该接口也是可以的。也许这是一个约定俗成的东西。所以最好定义一下。

 

加载配置文件得到SqlSessionFactory工具类代码：

package com.up;

import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisUtil {
	private static final SqlSessionFactory factory;
	static {
		String resource = "SqlMapConfig.xml";
		Reader reader = null;
		try {
			reader = Resources.getResourceAsReader(resource);
		} catch (Exception e) {
			e.printStackTrace();
		}
		factory = new SqlSessionFactoryBuilder().build(reader);
	}
	
	public static SqlSessionFactory getSqlSessionFactory(){
		return factory;
	}
	
}

主要的测试类，该类只是用于测试，所以各方法定义的不是那么灵活，可扩展。

package com.up;

import java.io.Reader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

/**
 * 在该类中，主要定义了几个方法，用来测试XML文件中的insert,update,delete,select语句
 * addStudent()方法对应了studentMapper.xml中的addStudent操作
 * getBoys()方法对应了studentMapper.xml中的selectBoy操作
 * getStudent()方法对应了studentMapper.xml中的selectByID操作
 * delStudent()方法对应了studentMapper.xml中的deleteStudent操作
 * updateStudent()方法对应了studentMapper.xml中的updateStudent操作
 * 
 * @author 小小虾
 *
 */
public class TestMybatis {
	
        private static SqlSessionFactory factory = null;
	static {
		factory = MyBatisUtil.getSqlSessionFactory();
	}
	
	public void addStudent(){
		SqlSession session = factory.openSession();
		StudentInfo student = new StudentInfo();
		student.setStuname("王王王");
		student.setStuid(00001);
		student.setStusex("男");
		student.setStuscore(88);
		student.setStuage(19);
		try {
			session.selectOne("StudentMapper.addStudent", student);
			session.commit();
		} finally {
			session.close();
		}
	}
	public void getBoys(){
		
                SqlSession session = factory.openSession();
		try {
			StudentMapper mapper = session.getMapper(StudentMapper.class);
			ArrayList list = mapper.selectBoy("男");
			for(int i=0;i<list.size();i++){
				StudentInfo stu = (StudentInfo)list.get(i);
				System.out.println(stu);
			}
		} finally {
			session.close();
		}
	}
	public void getStudent(){
		
                SqlSession session = factory.openSession();
		try {
			StudentMapper mapper = session.getMapper(StudentMapper.class);
			StudentInfo stu = mapper.selectByID(10018);
			System.out.println("信息："+stu);
		} finally {
			session.close();
		}
	}
	public void delStudent(){
		
		SqlSession session = factory.openSession();
		try {
			StudentMapper mapper = session.getMapper(StudentMapper.class);
			mapper.deleteStudent(10018);
			session.commit();
		} finally {
			session.close();
		}
	}
	public void updateStudent(){
		
                SqlSession session = factory.openSession();
		StudentInfo student = new StudentInfo();
		student.setStuname("swu");
		student.setStuid(10006);
		student.setStusex("女");
		student.setStuscore(111);
		student.setStuage(100);
		try {
			StudentMapper mapper = session.getMapper(StudentMapper.class);
			mapper.updateStudent(student);
			session.commit();
		} finally {
			session.close();
		}
	}
	public static void main(String[] args) {
		
                TestMybatis m = new TestMybatis();
		m.delStudent();
		m.getStudent();
	}
	
}

注意：

try {
	StudentMapper mapper = session.getMapper(StudentMapper.class);
	mapper.addStudent(student);
} finally {
	session.close();
}

session必须在finally中关闭。

 

 

至此，我的MyBatis初探就告一段落了，在此，要感谢网络上各位大侠。