首先由两个类Student和Grade。

package cn.wong.pojo;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name = "t_student")
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int stuId;
    private String stuName;
    private int age;

    @ManyToOne(cascade = CascadeType.ALL)
    // @ManyToOne(cascade=CascadeType.ALL,fetch=FetchType.LAZY) 启用懒加载
    @JoinColumn(name = "grade_Id", nullable = false)
    private Grade grade;

    public Student() {
        super();
    }

    public Student(int stuId, String stuName, int age, Grade grade) {
        super();
        this.stuId = stuId;
        this.stuName = stuName;
        this.age = age;
        this.grade = grade;
    }

    public int getStuId() {
        return stuId;
    }

    public void setStuId(int stuId) {
        this.stuId = stuId;
    }

    public String getStuName() {
        return stuName;
    }

    public void setStuName(String stuName) {
        this.stuName = stuName;
    }

    public int getAge() {
        return age;
    }

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

    public Grade getGrade() {
        return grade;
    }

    public void setGrade(Grade grade) {
        this.grade = grade;
    }

}

package cn.wong.pojo;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name = "t_grade")
public class Grade {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Id")
    private int gradeId;

    private String gradeName;

    @OneToMany(mappedBy = "grade", cascade = CascadeType.ALL)
    // @OneToMany(mappedBy="grade",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
    // 关闭延迟加载
    private Set<Student> students = new HashSet<Student>();

    public Grade() {

    }

    public Grade(int gradeId, String gradeName) {
        this.gradeId = gradeId;
        this.gradeName = gradeName;
    }

    public Grade(int gradeId, String gradeName, Set<Student> students) {
        this.gradeId = gradeId;
        this.gradeName = gradeName;
        this.students = students;
    }

    public Set<Student> getStudents() {
        return students;
    }

    public void setStudents(Set<Student> students) {
        this.students = students;
    }

    public int getGradeId() {
        return gradeId;
    }

    public void setGradeId(int gradeId) {
        this.gradeId = gradeId;
    }

    public String getGradeName() {
        return gradeName;
    }

    public void setGradeName(String gradeName) {
        this.gradeName = gradeName;
    }

}

测试比较简单，就省略了。