mybatis---demo1--(1-n)----bai

实体类1：

package com.etc.entity;

import java.util.List;

public class Teacher
{
	private int tid;
	private String tname;
	private String sex;
	private List<Student> students;
	public int getTid() {
		return tid;
	}
	public void setTid(int tid) {
		this.tid = tid;
	}
	public String getTname() {
		return tname;
	}
	public void setTname(String tname) {
		this.tname = tname;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public List<Student> getStudents() {
		return students;
	}
	public void setStudents(List<Student> students) {
		this.students = students;
	}
	@Override
	public String toString() {
		return "Teacher [sex=" + sex + ", tid=" + tid + ", tname=" + tname
				+ "]";
	}
}
=================================================
实体类2：

package com.etc.entity;

public class Student
{
	private int sid;
	private String sname;
	private String sex;
	private Teacher teacher;//外键的关联对象
	public int getSid() {
		return sid;
	}
	public void setSid(int sid) {
		this.sid = sid;
	}
	public String getSname() {
		return sname;
	}
	public void setSname(String sname) {
		this.sname = sname;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public Teacher getTeacher() {
		return teacher;
	}
	public void setTeacher(Teacher teacher) {
		this.teacher = teacher;
	}
	@Override
	public String toString() {
		return "Student [sex=" + sex + ", sid=" + sid + ", sname=" + sname
				+ "]";
	}
}
==================================================================
dao类1：

package com.etc.dao;

import java.util.List;

import com.etc.entity.Teacher;

public interface TeacherDao {
	Teacher findById(int id);
	List<Teacher> findAll();
}
===========================================
dao类2：

package com.etc.dao;

import com.etc.entity.Student;

public interface StudentDao
{
	Student findById(int id);
}
=============================================
工具类：

package com.etc.utils;

import java.io.InputStream;
import java.sql.Connection;

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 org.apache.log4j.lf5.util.Resource;

//实现获取、释放mybatis数据库连接的工具类
public class MyBatisSessionFactory {
	//定义常量
	private static String CONFIG_FILE_LOCATION="mybatis-config.xml";

	//考虑到该工具类允许被多线程执行。因为封装1个线程池，让每个线程从线程池中获取1个连接。让1个线程对应
	//1条数据库连接,这样更安全
	//ThreadLocal的作用：让"线程"绑定"资源",这样就不会出现多个线程同享资源的情况。更安全。牺牲内存，换取”安全“
	private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();

	private static InputStream is; //用于读取配置文件的流对象

	private static SqlSessionFactory fac;//用于管理多个连接的工厂。一个工厂对应1个数据库。

	//在该类的静态段中加载配置文件，这样可以确保只执行1次。
	static
	{
		try {
			is = Resources.getResourceAsStream(CONFIG_FILE_LOCATION);//读取配置文件
			fac = new SqlSessionFactoryBuilder().build(is);//通过配置文件创建1个连接工厂
		} catch (Exception e)
		{
			e.printStackTrace();
		}

	}
	//获取1条连接
	public static SqlSession getSession()
	{
		SqlSession s  = threadLocal.get(); //找线程池要1条连接
		if(s==null) //第1次时，拿不到，则由工厂获取1条连接并放入线程池
		{
			s = fac.openSession();//由工厂获取1条连接并放入线程池
			threadLocal.set(s);//放入线程池
		}
		return s;
	}

	//关闭连接
	public static void closeSession()
	{
		SqlSession s  = threadLocal.get();//找线程池要本线程对应的连接
		threadLocal.set(null);//将该连接从线程池中清除
		if(s!=null)
			s.close();//物理关闭连接
	}
}

==================================================
mybatis-config.xml 配置：

<?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.etc.entity.Student" alias="Student"/>
	<typeAlias type="com.etc.entity.Teacher" alias="Teacher"/>
</typeAliases>
<environments default="development">
<environment id="development">
   <transactionManager type="JDBC"/>
   <dataSource type="POOLED">
  	<property name="url" value="jdbc:mysql://127.0.0.1/java?characterEncoding=utf-8"/>
  	<property name="username" value="root"/>
  	<property name="password" value="root"/>
  	<property name="driver" value="com.mysql.jdbc.Driver"/>
  </dataSource>
</environment>
</environments>
<mappers>
  	<mapper resource="com/etc/mapper/Teacher-mapper.xml"/>
  	<mapper resource="com/etc/mapper/Student-mapper.xml"/>
</mappers>
</configuration>
===================================================
Student-mapper.xml  配置：

<?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.etc.dao.StudentDao">
	<resultMap type="Student" id="StudentMap">
		<id column="sid" property="sid" />
		<result column="sname" property="sname" />
		<result column="sex" property="sex" />
		<association property="teacher" resultMap="com.etc.dao.TeacherDao.TeacherMap"/>
	</resultMap>
	<select id="findById" parameterType="java.lang.Integer"
		resultMap="StudentMap">
		select t.tid,t.tname,t.sex,s.sid,s.sname,s.sex,s.tid
		from
		teacher t,student s where t.tid = s.tid
		and t.tid = #{id}
	</select>
</mapper>
=======================================
Teacher-mapper.xml  配置：

<?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.etc.dao.TeacherDao">
	<resultMap type="Teacher" id="TeacherMap">
		<id column="tid" property="tid" />
		<result column="tname" property="tname"/>
		<result column="sex" property="sex"/>
		<collection property="students" resultMap="com.etc.dao.StudentDao.StudentMap"/>
	</resultMap>
	<select id="findById" parameterType="java.lang.Integer" resultMap="TeacherMap">
		select t.tid,t.tname,t.sex,s.sid,s.sname,s.sex,s.tid
		from teacher t,student s where t.tid = s.tid
		and t.tid = #{id}
	</select>
    <select id="findAll"  resultMap="TeacherMap">
		select t.tid,t.tname,t.sex,s.sid,s.sname,s.sex,s.tid
		from teacher t,student s where t.tid = s.tid
	</select>
</mapper>
====================================================
log4j.properties  对log4j这个jar进行文件配置：

log4j.rootLogger=WARN, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
=========================================================================
测试类：

package com.etc.test;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import com.etc.dao.TeacherDao;
import com.etc.entity.Student;
import com.etc.entity.Teacher;
import com.etc.utils.MyBatisSessionFactory;
public class TestMybatis
{
	@Test
	public void testTeacherDao()
	{
		//1 获取连接
		SqlSession s = MyBatisSessionFactory.getSession();
		//2 执行查询
		Teacher t = s.getMapper(com.etc.dao.TeacherDao.class).findById(1);
		System.out.println("老师是"+t);
		System.out.println("学生列表如下:");
		for(Student stu:t.getStudents())
		{
			System.out.println(stu);
		}
		/*List<Teacher> list = s.getMapper(com.etc.dao.TeacherDao.class).findAll();
		for(Teacher t:list)
			System.out.println(t);*/
		//4 关闭
		MyBatisSessionFactory.closeSession();
	}
}
=========================================================================