MyBatis使用和配置详解

2018年2月25日 下午6:57

项目结构

MyBatis的重要依赖包

1. myBatis-3.2.3.jar
2. Mysql-connector-java-5.1.34.jar
   配置文件(xml)
3. TeacherMapper.xml
4. StudentMapper.xml
5. Reource.xml
   

配置文件详解：

TeacherMapper.xml

解析：

1. 本质：将sql语句与代码进行分离，方便管理
2. 绿色：是命名空间，是找到TeacherMapper.xml的关键标识，对应于测试代码TeacherEntity teacherEntity=sqlSession.selectOne("teacher.selectTeacherOne", "804”);中的teacher
3. 红色：是一个对应于*Entity.java实体的xml表示
4. 红色：是具体的sql的xml表示

   <!DOCTYPE mapper
   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
   <!-- namespace空间名称 -->
   <mapper namespace="teacher">
   
   	<cache></cache>
   	<!-- resultMap表示结果集 ，type表示对应的类，id表示当前标签的名称-->
   	<resultMap type="com.pan.teacher.TeacherEntity" id="teacher">
   		<!-- id标签表示当前要对应的表的主键 -->
   		<!-- column表示表中的列(字段)， property表示类中的属性-->
   		<id column="t_id" property="t_id" />
   		<!-- result表示当前表中除主键外的其他列 -->
   		<result column="t_name" property="t_name" />
   		<result column="t_sex" property="t_sex" />
   		<result column="t_birthday" property="t_birthday" />
   		<result column="prof" property="prof" />
   		<result column="depart" property="depart" />
   		<collection property="studentList" column="t_id" select="com.pan.test.StudentEntity.selectByT_id"></collection>
   	</resultMap>
   	<select id="selectTeacherOne" parameterType="string" resultMap="teacher">
   		select * from teacher where t_id=#{t_id}
   	</select>
   </mapper>

source.xml

解析：

1. 红色：是连接数据库的各种配置信息，用于登录数据库
2. 绿色：是用于声明项目中实体类对应的xml配置文件有哪些。

实体类

本质就是对应于数据库表字段的get，set方法

package com.pan.teacher;

import java.io.Serializable;
import java.util.List;

import com.pan.test.StudentEntity;

public class TeacherEntity implements Serializable{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private String t_id;
	private String t_name;
	private String t_sex;
	private String t_birthday;
	private String prof;
	private String depart;
	private List<StudentEntity> studentList;
	public String getT_id() {
		return t_id;
	}
	public void setT_id(String t_id) {
		this.t_id = t_id;
	}
	public String getT_name() {
		return t_name;
	}
	public void setT_name(String t_name) {
		this.t_name = t_name;
	}
	public String getT_sex() {
		return t_sex;
	}
	public void setT_sex(String t_sex) {
		this.t_sex = t_sex;
	}
	public String getT_birthday() {
		return t_birthday;
	}
	public void setT_birthday(String t_birthday) {
		this.t_birthday = t_birthday;
	}
	public String getProf() {
		return prof;
	}
	public void setProf(String prof) {
		this.prof = prof;
	}
	public String getDepart() {
		return depart;
	}
	public void setDepart(String depart) {
		this.depart = depart;
	}
	public List<StudentEntity> getStudentList() {
		return studentList;
	}
	public void setStudentList(List<StudentEntity> studentList) {
		this.studentList = studentList;
	}
	
}

测试

package com.pan.teacher;

import java.io.IOException;
import java.io.Reader;
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;

import com.pan.test.StudentEntity;

public class TeacherTest {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub

		//读取myBatis的核心配置文件
		Reader reader=Resources.getResourceAsReader("reource.xml");
		//创建二级缓存
		SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(reader);
		//创建一级缓存
		SqlSession sqlSession=sessionFactory.openSession();
		
		//-------------------级联查询----------------
		//注意：在myBatis中只有级联查询，没有级联增删改
		TeacherEntity teacherEntity=sqlSession.selectOne("teacher.selectTeacherOne", "804");
		System.out.println(teacherEntity.getT_name());
		List<StudentEntity> list=teacherEntity.getStudentList();
		System.out.println(list.size());
	}

}