MyBatis中的三种映射方法(2)

1、先在数据库里创建student表、course表、student_course桥表（里面存放student的id和course的id）

create table course (
id number primary key,
course_code varchar2(30) not null,
course_name varchar2(30) not null
);
create table student (
id number primary key,
name varchar2(10) not null,
gender varchar2(10) ,
major varchar2(10) ,
grade varchar2(10)
);
create table student_course (
id number primary key,
student_id number references student(id),
course_id number references course(id)
);

2、建立实体类

Student.java

package com.briup.ManyToMany;

import java.util.List;

public class Student {
	private Integer id;
	private String name;
	private String gender;
	private String major;
	private String grade;
	private List courses;
	public Student() {
		super();
	}
	
	public Student(String name, String gender, String major, String grade) {
		super();
		this.name = name;
		this.gender = gender;
		this.major = major;
		this.grade = grade;
	}

	public Student(Integer id, String name, String gender, String major, String grade, List courses) {
		super();
		this.id = id;
		this.name = name;
		this.gender = gender;
		this.major = major;
		this.grade = grade;
		this.courses = courses;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	public String getMajor() {
		return major;
	}
	public void setMajor(String major) {
		this.major = major;
	}
	public String getGrade() {
		return grade;
	}
	public void setGrade(String grade) {
		this.grade = grade;
	}
	public List getCourses() {
		return courses;
	}
	public void setCourses(List courses) {
		this.courses = courses;
	}
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", gender=" + gender + ", major=" + major + ", grade=" + grade
				+ ", courses=" + courses + "]";
	}
	

}

Course.java

package com.briup.ManyToMany;

import java.util.List;

public class Course {
	private Integer id;
	private String courseCode;
	private String courseName;
	private List students;
	public Course() {
		super();
	}
	
	public Course(Integer id, String courseCode, String courseName) {
		super();
		this.id = id;
		this.courseCode = courseCode;
		this.courseName = courseName;
	}
	

	public Course(String courseCode, String courseName) {
		super();
		this.courseCode = courseCode;
		this.courseName = courseName;
	}

	public Course(Integer id, String courseCode, String courseName, List students) {
		super();
		this.id = id;
		this.courseCode = courseCode;
		this.courseName = courseName;
		this.students = students;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getCourseCode() {
		return courseCode;
	}
	public void setCourseCode(String courseCode) {
		this.courseCode = courseCode;
	}
	public String getCourseName() {
		return courseName;
	}
	public void setCourseName(String courseName) {
		this.courseName = courseName;
	}
	public List getStudents() {
		return students;
	}
	public void setStudents(List students) {
		this.students = students;
	}
	@Override
	public String toString() {
		return "Course [id=" + id + ", courseCode=" + courseCode + ", courseName=" + courseName + ", students="
				+ students + "]";
	}
	

}

3、创建映射接口

StudentMapper.java

package com.briup.ManyToMany;

import java.util.List;

public interface StudentMapper {
	//插入student数据
	public void insertStudent(Student student);
	//插入course数据
	public void insertCourse(Course course);
	//通过id查询学生
	public Student getStudentById(Integer id);
	//通过id查询课程
	public Course getCourseById(Integer id);
	//学生x选课y
	public void studentSelectCourse(Student student, Course course);
	//查询比指定id值小的学生信息
	public List getStudentByIdonCondition(Integer id);
	//查询student级联查询出所选的course并且组装成完整的对象
	public Student getStudentByIdWithCourses(Integer id);

}

4、创建映射文件

StudentMapper.xml（我只写了嵌套结果，没有写嵌套查询）

	
		
		
		
		
		
	
	
	
		
		
		
	
	
	
		
		
		
		
		
		
	

	
	
		
			select my_seq.nextval from dual
		
		insert into student(id,name,gender,major,grade)
		values(#{id},#{name},#{gender},#{major},#{grade})
	
	
	
	
		
			select my_seq.nextval from dual
		
		insert into course(id,course_code,course_name)
		values(#{id},#{courseCode},#{courseName})
	
	
	
	
		select *
		from student
		where id=#{id}
	
	
	
	
		select *
		from course
		where id=#{id}
	
	
	
	
		insert into student_course(id,student_id,course_id)
		values(my_seq.nextval,#{param1.id},#{param2.id})
	
	
	
	
		select *
		from student
		where id#{id}
	
	
	
	
		select s.id as sid,s.name,s.gender,s.major,s.grade,c.id as cid,c.course_code,c.course_name
		from student s,course c,student_course sc
		where s.id=sc.student_id 
			and c.id=sc.course_id 
			and s.id=#{id}
	

5、测试代码

StudentTest.java

package com.briup.ManyToMany;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.briup.utils.MySqlsessionFactoryUtil;

public class StudentTest {
	@Test
	public void insertStudent() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		Student student = new Student("小立","女","信管","大四");
		mapper.insertStudent(student);
		sqlSession.commit();
	}
	@Test
	public void insertCourse() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		Course course = new Course("002","mybatis");
		mapper.insertCourse(course);
		sqlSession.commit();
	}
	@Test
	public void getStudentById() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		Student student = mapper.getStudentById(1);
		System.out.println(student);
	}
	@Test
	public void getCourseById() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		Course course = mapper.getCourseById(1);
		System.out.println(course);
	}
	
	@Test
	public void studentSelectCourse() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		Student student = mapper.getStudentById(1);
		Course course = mapper.getCourseById(1);
		mapper.studentSelectCourse(student, course);
		sqlSession.commit();
	}
	
	@Test
	public void getStudentByIdWithCourses() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		Student student = mapper.getStudentByIdWithCourses(1);
		System.out.println(student);
	}
	
	@Test
	public void getStudentByIdonCondition() {
		SqlSession sqlSession = MySqlsessionFactoryUtil.getSqlSessionFactoryBuilder().openSession();
		StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
		List student = mapper.getStudentByIdonCondition(4);
		System.out.println(student);
	}

}