Mybatis中的一对多及多对一举例-白红宇

这次要连数据库建表及插入的数据都列表，

推导和理解起来，就通畅多了。

adea227c0357b072d69added026f4d6eeb5b512f

建表及插入数据：

CREATE TABLE tb_clazz(  id INT PRIMARY KEY AUTO_INCREMENT,  CODE VARCHAR(18),  NAME VARCHAR(18));INSERT INTO tb_clazz(CODE, NAME) VALUES('j1601', 'Java');INSERT INTO tb_clazz(CODE, NAME) VALUES('j1602', 'Python');INSERT INTO tb_clazz(CODE, NAME) VALUES('j1603', 'Javascript');INSERT INTO tb_clazz(CODE, NAME) VALUES('j1604', 'Go');CREATE TABLE tb_student(  id INT PRIMARY KEY AUTO_INCREMENT,  NAME VARCHAR(18),  SEX CHAR(18),  AGE INT,  clazz_id INT,  FOREIGN KEY (clazz_id) REFERENCES tb_clazz(id));INSERT INTO tb_student(NAME, SEX, AGE, clazz_id) VALUES('jack', 'M', 22, 1);INSERT INTO tb_student(NAME, SEX, AGE, clazz_id) VALUES('rose', 'F', 18, 1);INSERT INTO tb_student(NAME, SEX, AGE, clazz_id) VALUES('tom', 'M', 25, 2);INSERT INTO tb_student(NAME, SEX, AGE, clazz_id) VALUES('mary', 'F', 20, 2);INSERT INTO tb_student(NAME, SEX, AGE, clazz_id) VALUES('tommy', 'M', 25, 4);INSERT INTO tb_student(NAME, SEX, AGE, clazz_id) VALUES('jacky', 'F', 20, 4);

clazz.java

package org.fkit.domain;import java.util.List;public class Clazz {	private Integer id;	private String code;	private String name;	private List
    
      students;	public Integer getId() {		return id;	}	public void setId(Integer id) {		this.id = id;	}	public String getCode() {		return code;	}	public void setCode(String code) {		this.code = code;	}	public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}	public List
     
       getStudents() {		return students;	}	public void setStudents(List
      
        students) {		this.students = students;	}	@Override	public String toString() {		return "Clazz [id=" + id + ", code=" + code + ", name=" + name + "]";	}			}

Student.java

package org.fkit.domain;public class Student {	private Integer id;	private String name;	private String sex;	private Integer age;	private Clazz clazz;	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 Clazz getClazz() {		return clazz;	}	public void setClazz(Clazz clazz) {		this.clazz = clazz;	}	@Override	public String toString() {		return "Student [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + "]";	}		}

ClassMapper.xml

StudentMapper.xml

OneToManyTest.java

package org.fkit.tst;import java.util.List;import org.apache.ibatis.session.SqlSession;import org.fkit.domain.Clazz;import org.fkit.domain.Student;import org.fkit.factory.FKSqlSessionFactory;import org.fkit.mapper.ClazzMapper;import org.fkit.mapper.StudentMapper;public class OneToManyTest {	public static void main(String[] args) throws Exception {		// TODO Auto-generated method stub		SqlSession session = FKSqlSessionFactory.getSqlSession();				OneToManyTest t = new OneToManyTest();		t.testSelectClazzById(session);		t.testSelectStudentById(session);		session.commit();		session.close();	}		public void testSelectClazzById(SqlSession session) {		ClazzMapper cm = session.getMapper(ClazzMapper.class);		Clazz clazz = cm.selectClazzById(4);		System.out.println(clazz.getId() + " " + clazz.getCode() + " " + clazz.getName()); 		List
    
      students = clazz.getStudents();		for (Student stu : students) {			System.out.println(stu);		}	}		public void testSelectStudentById(SqlSession session) {		StudentMapper sm = session.getMapper(StudentMapper.class);		Student stu = sm.selectStudentById(1);		System.out.println(stu);		System.out.println(stu.getClazz());	}}

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