Spring boot + mybatis resultMap高级映射(一对一、一对多、多对多)

application.properties配置文件

############################################
##  MySQL数据库连接
############################################
spring.datasource.url = jdbc:mysql://localhost:3306/dongsuo_test?useUnicode=true&characterEncoding=utf8&useSSL=false
spring.datasource.username = root
spring.datasource.password = 123456
spring.datasource.driverClassName = com.mysql.jdbc.Driver
############################################
##  配置自动建表：updata:没有表新建，有表更新操作,控制台显示建表语句
############################################
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
############################################
# 加载mybatis 配置的Mapper
############################################
mybatis.mapper-locations=classpath:mybatisMapper/*Mapper.xml

1、创建所用到的表

-- 学生表
create table student(
id int primary key auto_increment,
name varchar(20),
sex varchar(8),
age int
) ENGINE=InnoDB  DEFAULT CHARSET=utf8

alter table student add column c_id int;
alter table student add constraint foreign key(c_id) references headclass(hc_id)

insert into student(name,sex,age,c_id) values('tom','男',20,1);
insert into student(name,sex,age,c_id) values('jack','男',18,2);
insert into student(name,sex,age,c_id) values('chen','男',21,1);
-- 课程表
create table course(
id int primary key auto_increment,
name varchar(20),
credit int
)ENGINE=InnoDB  DEFAULT CHARSET=utf8

insert into course(name,credit) values('Math',5);
insert into course(name,credit) values('Computer',3);
-- 学生课程中间表
create table student_course(
s_id int,
c_id int,
sc_date date,
primary key(s_id,c_id),
foreign key(s_id) references student(id),
foreign key(c_id) references course(id)
)ENGINE=InnoDB DEFAULT CHARSET=utf8

insert into student_course(s_id,c_id,sc_date) values(1,1,'2018-01-01');
insert into student_course(s_id,c_id,sc_date) values(1,2,'2018-01-02');
insert into student_course(s_id,c_id,sc_date) values(2,1,'2018-02-01');
insert into student_course(s_id,c_id,sc_date) values(2,2,'2018-06-12');
-- 班主任表
create table headtecher(
ht_id int primary key auto_increment,
ht_name varchar(20),
ht_age int
)engine=InnoDB default charset=utf8

insert into headtecher(ht_name,ht_age) values('张三',35);
insert into headtecher(ht_name,ht_age) values('刘能',40);

select *from headtecher;
-- 班级表
create table headclass(
hc_id int primary key auto_increment,
hc_name varchar(20),
ht_id int unique,
foreign key(ht_id) references headtecher(ht_id)
)engine=InnoDB default charset=utf8

insert into headclass(hc_name,ht_id) values('软件工程（1）班',1);
insert into headclass(hc_name,ht_id) values('软件工程（2）班',2)

2、创建实体类

     学生实体：

public class Student {
    private Integer id;
    private String name;
    private String sex;
    private Integer age;
    private List courses;  //多对多

    public Student() {
    }

    public Student(Integer id, String name, String sex, Integer age, List courses) {
        this.id = id;
        this.name = name;
        this.sex = sex;
        this.age = age;
        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 getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public List getCourses() {
        return courses;
    }

    public void setCourses(List courses) {
        this.courses = courses;
    }
}

     课程实体：

public class Course {
    private Integer id;
    private String name;
    private Integer credit;
    private List students; //多对多

    public Course() {
    }

    public Course(Integer id, String name, Integer credit, List students) {
        this.id = id;
        this.name = name;
        this.credit = credit;
        this.students = students;
    }

    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 Integer getCredit() {
        return credit;
    }

    public void setCredit(Integer credit) {
        this.credit = credit;
    }

    public List getStudents() {
        return students;
    }

    public void setStudents(List students) {
        this.students = students;
    }
}

    学生课程实体：

public class StudentCourse {

    private Student student;
    private Course course;
    private Date date;

    public StudentCourse() {
    }

    public StudentCourse(Student student, Course course, Date date) {
        this.student = student;
        this.course = course;
        this.date = date;
    }

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public Course getCourse() {
        return course;
    }

    public void setCourse(Course course) {
        this.course = course;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }
}

    班主任实体：

public class HeadTecher {

    private Integer tid;
    private String tname;
    private Integer tage;

    public HeadTecher() {
    }

    public Integer getTid() {
        return tid;
    }

    public void setTid(Integer tid) {
        this.tid = tid;
    }

    public String getTname() {
        return tname;
    }

    public void setTname(String tname) {
        this.tname = tname;
    }

    public Integer getTage() {
        return tage;
    }

    public void setTage(Integer tage) {
        this.tage = tage;
    }
}

    班级实体：

public class HeadClass {
    private Integer cid;
    private String cname;
    private HeadTecher headTecher;//用于一对一

    private List students;//用于一对多

    public HeadClass() {
    }

    public Integer getCid() {
        return cid;
    }

    public void setCid(Integer cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }

    public HeadTecher getHeadTecher() {
        return headTecher;
    }

    public void setHeadTecher(HeadTecher headTecher) {
        this.headTecher = headTecher;
    }

    public List getStudents() {
        return students;
    }

    public void setStudents(List students) {
        this.students = students;
    }
}

3、创建Mapper

        HeadClassMapper:

@Mapper
@Repository
public interface HeadClassMapper {

    HeadClass selectClassById(@Param("id") Integer id);

    List getHeadTecher();

    List selectClassAndStudentById(@Param("id") Integer id);
}

      StudentMapper:

@Mapper
@Repository
public interface StudentMapper {

    public List selectStudentCourse();

}

   StudentAllMapper:

@Mapper
@Repository
public interface StudentAllMapper {

   List linkTableSel(@Param("id") Integer id);
}

4、创建Mapper对应的Mapper.xml文件

     HeadClassMapper.xml:

xml version="1.0" encoding="UTF-8"?>
mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
namespace="com.study.springboot.mybatis.mapper.HeadClassMapper">
    
    id="techermap" type="com.study.springboot.mybatis.entity.HeadTecher">
        property="tid" column="ht_id" />
        property="tname" column="ht_name" />
        property="tage" column="ht_age" />
    
    id="classmap" type="com.study.springboot.mybatis.entity.HeadClass">
        property="cid" column="hc_id" />
        property="cname" column="hc_name"/>
        property="headTecher" column="ht_id" resultMap="techermap" />
    
    
    id="selectClassById" resultMap="classmap">
        SELECT *FROM
        headclass hc,headtecher ht
        WHERE hc.ht_id=ht.ht_id
        AND hc.hc_id=#{id}
    

    id="getHeadTecher" resultMap="techermap">
        SELECT * FROM headtecher
    

    
    id="classmap2" type="com.study.springboot.mybatis.entity.HeadClass">
        property="cid" column="hc_id" />
        property="cname" column="hc_name" />
        property="headTecher" column="ht_id" resultMap="techermap" />
        property="students" ofType="com.study.springboot.mybatis.entity.Student">
            property="id" column="id"/>
            property="name" column="name"/>
            property="sex" column="sex"/>
            property="age" column="age" />
        
    
    
    id="selectClassAndStudentById" resultMap="classmap2">
        SELECT
        *FROM
        headclass hc,student s,headtecher ht
        WHERE
        hc.hc_id=s.c_id AND hc.ht_id=ht.ht_id
        AND
        hc.hc_id=#{id}
    

       StudentMapper.xml:

xml version="1.0" encoding="UTF-8"?>
mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
namespace="com.study.springboot.mybatis.mapper.StudentMapper">

    
    id="studentCourseMap" type="com.study.springboot.mybatis.entity.Student">
        column="id" property="id">
        column="name" property="name">
        column="sex" property="sex">
        column="age" property="age">
        property="courses" ofType="com.study.springboot.mybatis.entity.Course">
            property="id" column="id">
            property="name" column="name">
            property="credit" column="credit">
        
    
    id="selectStudentCourse" resultMap="studentCourseMap">
          SELECT
          s.*,
          c.*
          FROM student s,course c,student_course sc
          WHERE s.id=sc.s_id AND c.id=sc.c_id
    

        StudentAllMapper.xml(关系整合):

xml version="1.0" encoding="UTF-8"?>
mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
namespace="com.study.springboot.mybatis.mapper.StudentAllMapper">
    
    id="studentmap" type="com.study.springboot.mybatis.entity.Student">
        property="id" column="id"/>
        property="name" column="name"/>
        property="sex" column="sex" />
        property="age" column="age" />
        property="courses" resultMap="coursemap" />
    
    id="coursemap" type="com.study.springboot.mybatis.entity.Course">
        property="id" column="id" />
        property="name" column="name" />
        property="credit" column="credit" />
    
    id="techermap" type="com.study.springboot.mybatis.entity.HeadTecher">
        property="tid" column="ht_id" />
        property="tname" column="ht_name" />
        property="tage" column="ht_age" />
    
    id="classmap" type="com.study.springboot.mybatis.entity.HeadClass">
        property="cid" column="hc_id" />
        property="cname" column="hc_name"/>
        property="headTecher" column="ht_id" resultMap="techermap" />
        property="students" ofType="com.study.springboot.mybatis.entity.Student" resultMap="studentmap"/>
    

    id="linkTableSel" resultMap="classmap">
        select
        *from
        student S
        left join student_course SC on S.id=SC.s_id
        left join course C on SC.c_id=C.id
        left join headclass HC on S.c_id=HC.hc_id
        left join headtecher HT on HC.ht_id=HT.ht_id
        where 1=1
        test="id!=null">
            AND S.id=#{id}
        
    

5、接口调用

@Autowired
private HeadClassMapper headClassMapper;
@RequestMapping(value = "/classInfo",method = RequestMethod.GET,produces = {"application/json"})
public DataResponseVo getClassInfo(@RequestParam(value = "id",required = true) Integer id){
    return new DataResponseVo(0,headClassMapper.selectClassById(id));
}

@RequestMapping(value = "/getTecherinfo",method = RequestMethod.GET,produces = {"application/json"})
public DataResponseVo getHeadTecher(){
    return new DataResponseVo(0,headClassMapper.getHeadTecher());
}
@RequestMapping(value = "/getclassandstudent",method = RequestMethod.GET,produces = {"application/json"})
public DataResponseVo getClassAndStudent(@RequestParam(value = "id",required = true) Integer id){
    return new DataResponseVo(0,headClassMapper.selectClassAndStudentById(id));
}

@Autowired
private StudentMapper studentMapper;
@Autowired
private StudentAllMapper studentAllMapper;

@RequestMapping(value = "/info",method = RequestMethod.GET,produces = {"application/json"})
public DataResponseVo getStudentInfo(){
    return new DataResponseVo(0,studentMapper.selectStudentCourse());
}
@RequestMapping(value = "/linktable",method = RequestMethod.GET,produces = {"application/json"})
public DataResponseVo getlinkTableSel(@RequestParam(value = "id",required = true) Integer id){
    return new DataResponseVo(0,studentAllMapper.linkTableSel(id));
}

6、返回结果

{
    "code": 0,
    "content": [
        {
            "cid": 1,
            "cname": "软件工程（1）班",
            "headTecher": {
                "tid": 1,
                "tname": "张三",
                "tage": 35
            },
            "students": [
                {
                    "id": 1,
                    "name": "tom",
                    "sex": "男",
                    "age": 20,
                    "courses": [
                        {
                            "id": 1,
                            "name": "tom",
                            "credit": 5,
                            "students": null
                        }
                    ]
                },
                {
                    "id": 3,
                    "name": "chen",
                    "sex": "男",
                    "age": 21,
                    "courses": [
                        {
                            "id": 3,
                            "name": "chen",
                            "credit": null,
                            "students": null
                        }
                    ]
                }
            ]
        },
        {
            "cid": 2,
            "cname": "软件工程（2）班",
            "headTecher": {
                "tid": 2,
                "tname": "刘能",
                "tage": 40
            },
            "students": [
                {
                    "id": 2,
                    "name": "jack",
                    "sex": "男",
                    "age": 18,
                    "courses": [
                        {
                            "id": 2,
                            "name": "jack",
                            "credit": 5,
                            "students": null
                        }
                    ]
                }
            ]
        }
    ]
}