mybatis高级映射一对一、一对多、多对多

小鱼儿 2022-05-24 08:10 222阅读 0赞

一对一用assosiation用javaType

多对多用的是collection,用的是ofType

一对一

在Cunstomer类中加入Orders orders类型的属性并生产get、set方法

一对多

<resultMap type="com.yc.m.Customer" id="resultCustomerMap"> 
        <id column="id" jdbcType="INTEGER" property="id" />
        <result property="address" column="address"/> 
        <result property="postcode" column="postcode"/> 
        <result property="sex" column="sex"/> 
        <result property="cname" column="cname"/> 
        <collection property="orders" ofType="com.yc.m.Orders">
              <id property="id" column="id"/>
              <result property="code" column="code"/>
        </collection>
      </resultMap>
    collection property="orders" ofType="com.yc.m.Orders">
              <id property="id" column="id"/>
              <result property="code" column="code"/>
        </collection>
      </resultMap>

在Cunstomer类中加入List<Orders> orders类型的属性并生产get、set方法

多对多

public class Course {  
                private Integer id;  
                private String courseCode; // 课程编号  
                private String courseName;// 课程名称  
                private List<Student> students;// 选课学生  
               // get/set  
                public Course() {}  
            public Course(Integer id, String courseCode, String courseName) {  
                super();  
                this.id = id;  
                this.courseCode = courseCode;  
                this.courseName = courseName;  
            }  
            public Course(Integer id, String courseCode, String courseName,  
                    List<Student> students) {  
                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<Student> getStudents() {  
                return students;  
            }  
            public void setStudents(List<Student> students) {  
                this.students = students;  
            }  
            @Override  
            public String toString() {  
                return "Course [id=" + id + ", courseCode=" + courseCode  
                        + ", courseName=" + courseName + ", students=" + students  
                        + "]";  
            }  
    }   Course {  
                private Integer id;  
                private String courseCode; // 课程编号  
                private String courseName;// 课程名称  
                private List<Student> students;// 选课学生  
               // get/set  
                public Course() {}  
            public Course(Integer id, String courseCode, String courseName) {  
                super();  
                this.id = id;  
                this.courseCode = courseCode;  
                this.courseName = courseName;  
            }  
            public Course(Integer id, String courseCode, String courseName,  
                    List<Student> students) {  
                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<Student> getStudents() {  
                return students;  
            }  
            public void setStudents(List<Student> students) {  
                this.students = students;  
            }  
            @Override  
            public String toString() {  
                return "Course [id=" + id + ", courseCode=" + courseCode  
                        + ", courseName=" + courseName + ", students=" + students  
                        + "]";  
            }  
    }

public class Student {  
                private Integer id;  
                private String name; // 姓名  
                private String gender; // 性别  
                private String major; // 专业  
                private String grade; // 年级  
                private List<Course> courses;// 所选的课程  
            public Student(Integer id, String name, String gender,String major, String grade, List<Course> courses) {  
                    super();  
                    this.id = id;  
                    this.name = name;  
                    this.gender = gender;  
                    this.major = major;  
                    this.grade = grade;  
                    this.courses = courses;  
                }  
            public Student(Integer id, String name, String gender, String major,  
                    String grade) {  
                super();  
                this.id = id;  
                this.name = name;  
                this.gender = gender;  
                this.major = major;  
                this.grade = grade;  
            }  
            public Student() {  
                super();  
            }  
            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<Course> getCourses() {  
                return courses;  
            }  
            public void setCourses(List<Course> courses) {  
                this.courses = courses;  
            }  
            @Override  
            public String toString() {  
                return "Student [id=" + id + ", name=" + name + ", gender="  
                        + gender + ", major=" + major + ", grade=" + grade  
                        + ", courses=" + courses + "]";  
            }  
                  
            }  Student {  
                private Integer id;  
                private String name; // 姓名  
                private String gender; // 性别  
                private String major; // 专业  
                private String grade; // 年级  
                private List<Course> courses;// 所选的课程  
            public Student(Integer id, String name, String gender,String major, String grade, List<Course> courses) {  
                    super();  
                    this.id = id;  
                    this.name = name;  
                    this.gender = gender;  
                    this.major = major;  
                    this.grade = grade;  
                    this.courses = courses;  
                }  
            public Student(Integer id, String name, String gender, String major,  
                    String grade) {  
                super();  
                this.id = id;  
                this.name = name;  
                this.gender = gender;  
                this.major = major;  
                this.grade = grade;  
            }  
            public Student() {  
                super();  
            }  
            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<Course> getCourses() {  
                return courses;  
            }  
            public void setCourses(List<Course> courses) {  
                this.courses = courses;  
            }  
            @Override  
            public String toString() {  
                return "Student [id=" + id + ", name=" + name + ", gender="  
                        + gender + ", major=" + major + ", grade=" + grade  
                        + ", courses=" + courses + "]";  
            }  
                  
            }

<resultMap id="StudentResult" type="Student">  
                <id property="id" column="id"/>  
                <result property="name" column="name"/>  
                <result property="gender" column="gender"/>  
                <result property="major" column="major"/>  
                <result property="grade" column="grade"/>  
            </resultMap>  
              
            <resultMap id="StudentResultWithCourses" type="Student" extends="StudentResult">  
                <collection property="courses" resultMap="CourseResult"></collection>  
            </resultMap>  
              
            <resultMap id="CourseResult" type="Course">  
                <id property="id" column="cid"/>  
                <result property="courseCode" column="course_code"/>  
                <result property="courseName" column="course_name"/>  
            </resultMap>  
              
            <select id="getStudentByIdWithCourses" parameterType="int" resultMap="StudentResultWithCourses">  
                select s.id,s.name,s.gender,s.major,s.grade,c.id as cid,c.course_code,c.course_name,sc.id,sc.student_id,sc.course_id  
                from student s,course c,student_course sc  
                where    
                s.id=#{id}  
                and  
                s.id=sc.student_id    
                and    
                sc.course_id=c.id  
            </select>  collection property="courses" resultMap="CourseResult"></collection>  
            </resultMap>  
              
            <resultMap id="CourseResult" type="Course">  
                <id property="id" column="cid"/>  
                <result property="courseCode" column="course_code"/>  
                <result property="courseName" column="course_name"/>  
            </resultMap>  
              
            <select id="getStudentByIdWithCourses" parameterType="int" resultMap="StudentResultWithCourses">  
                select s.id,s.name,s.gender,s.major,s.grade,c.id as cid,c.course_code,c.course_name,sc.id,sc.student_id,sc.course_id  
                from student s,course c,student_course sc  
                where    
                s.id=#{id}  
                and  
                s.id=sc.student_id    
                and    
                sc.course_id=c.id  
            </select>