Spring Data JPA 的一对多，一对多，多对多操作

一对一的关联关系

需求：用户与角色的一对一的关联关系

用户：一方

角色：一方

创建 Users 实体

@Entity
@Table(name = "t_users")
public class Users implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)//自增长
    @Column(name = "userid")
    private Integer userid;

    private String username;

    private Integer userage;

    @OneToOne(cascade = CascadeType.PERSIST)
    //@ManyToOne(cascade = CascadeType.PERSIST)
    @JoinColumn(name = "fk_roles_id")
    private Roles roles;

创建Roles实体

@Entity
@Table(name = "t_roles")
public class Roles {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "roleid")
    private Integer roleid;

    @Column(name = "rolename")
    private String rolename;

    @OneToOne(mappedBy = "roles")
    private Users users;

一对一关联关系操作

com.bjsxt.dao.UserDao

package com.bjsxt.dao;

import com.bjsxt.pojo.Users;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface UserDao extends JpaRepository<Users,Integer>, JpaSpecificationExecutor<Users> {

}

com.bjsxt.test.UserTest

   @Test
    public void addUserAndRole(){
        Roles roles=new Roles();
        roles.setRolename("管理员");

        Users users=new Users();
        users.setUsername("yxf");
        users.setUserage(22);

        //建立关系
        users.setRoles(roles);
        roles.setUsers(users);

        userDao.save(users);

一对多的关联关系

需求：从角色到用户的一对多的关联关系

角色：一方

用户：多方

创建 Users 实体

package com.bjsxt.pojo;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "t_users")
public class Users implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)//自增长
    @Column(name = "userid")
    private Integer userid;

    private String username;

    private Integer userage;

   // @OneToOne(cascade = CascadeType.PERSIST)
    @ManyToOne(cascade = CascadeType.PERSIST)
    @JoinColumn(name = "fk_roles_id")
    private Roles roles;
    public Users(){}

    public Integer getUserid() {
        return userid;
    }

    public void setUserid(Integer userid) {
        this.userid = userid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getUserage() {
        return userage;
    }

    public void setUserage(Integer userage) {
        this.userage = userage;
    }

    public Roles getRoles() {
        return roles;
    }

    public void setRoles(Roles roles) {
        this.roles = roles;
    }

    public Users(String username, Integer userage, Roles roles) {
        this.username = username;
        this.userage = userage;
        this.roles = roles;
    }

    @Override
    public String toString() {
        return "Users{" +
                "userid=" + userid +
                ", username='" + username + '\'' +
                ", userage=" + userage +
                ", roles=" + roles +
                '}';
    }
}

创建 Roles 实体

package com.bjsxt.pojo;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "t_roles")
public class Roles {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "roleid")
    private Integer roleid;

    @Column(name = "rolename")
    private String rolename;

    //@OneToOne(mappedBy = "roles")
    //private Users users;
    @OneToMany(mappedBy = "roles",cascade = CascadeType.PERSIST)
    private Set<Users> users=new HashSet<>();

    public Roles(String rolename, Set<Users> users) {
        this.rolename = rolename;
        this.users = users;
    }

    @Override
    public String toString() {
        return "Roles{" +
                "roleid=" + roleid +
                ", rolename='" + rolename + '\'' +
                ", users=" + users +
                '}';
    }

    public Integer getRoleid() {
        return roleid;
    }

    public void setRoleid(Integer roleid) {
        this.roleid = roleid;
    }

    public String getRolename() {
        return rolename;
    }

    public void setRolename(String rolename) {
        this.rolename = rolename;
    }

    public Set<Users> getUsers() {
        return users;
    }

    public void setUsers(Set<Users> users) {
        this.users = users;
    }

    public Roles(){}

}

一对多的关联关系操作

 @Test
    public void addUserAndRole(){
        Roles roles=new Roles();
        roles.setRolename("班长");

        Users users=new Users();
        users.setUsername("xm");
        users.setUserage(22);

        Users users1=new Users();
        users1.setUsername("hw");
        users1.setUserage(23);
        Set<Users> set = roles.getUsers();

        set.add(users);
        set.add(users1);

        users.setRoles(roles);
        users1.setRoles(roles);

        userDao.save(users);
        userDao.save(users1);

    }

多对多的关联关系

需求：一个角色可以拥有多个菜单，一个菜单可以分配多个角色。多对多的关联关系

角色：多方

菜单：多方

创建 Roles 实体

package com.bjsxt.pojo;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "t_roles")
public class Roles {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "roleid")
    private Integer roleid;

    @Column(name = "rolename")
    private String rolename;

    @ManyToMany(cascade = CascadeType.PERSIST,fetch = FetchType.EAGER)
    @JoinTable(name = "t_menus_roles",joinColumns = @JoinColumn(name = "role_id"),inverseJoinColumns = @JoinColumn(name = "menu_id"))
    private Set<Menus> menus=new HashSet<>();

    public Roles(){}

    @Override
    public String toString() {
        return "Roles{" +
                "roleid=" + roleid +
                ", rolename='" + rolename + '\'' +
                ", menus=" + menus +
                '}';
    }

    public Integer getRoleid() {
        return roleid;
    }

    public void setRoleid(Integer roleid) {
        this.roleid = roleid;
    }

    public String getRolename() {
        return rolename;
    }

    public void setRolename(String rolename) {
        this.rolename = rolename;
    }

    public Set<Menus> getMenus() {
        return menus;
    }

    public void setMenus(Set<Menus> menus) {
        this.menus = menus;
    }

    public Roles(String rolename, Set<Menus> menus) {
        this.rolename = rolename;
        this.menus = menus;
    }
}

创建 Menus 实体

package com.bjsxt.pojo;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "t_menus")
public class Menus {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "menusid")
    private  Integer menusid;

    @Column(name = "menusname")
    private String menusname;

    @Column(name = "menusurl")
    private String menusurl;

    @Column(name = "fatherid")
    private Integer fatherid;

    @ManyToMany(mappedBy = "menus")
    private Set<Roles> roles=new HashSet<>();

    public Menus(){}

    @Override
    public String toString() {
        return "Menus{" +
                "menusid=" + menusid +
                ", menusname='" + menusname + '\'' +
                ", menusurl='" + menusurl + '\'' +
                ", fatherid=" + fatherid +
                ", roles=" + roles +
                '}';
    }

    public Integer getMenusid() {
        return menusid;
    }

    public void setMenusid(Integer menusid) {
        this.menusid = menusid;
    }

    public String getMenusname() {
        return menusname;
    }

    public void setMenusname(String menusname) {
        this.menusname = menusname;
    }

    public String getMenusurl() {
        return menusurl;
    }

    public void setMenusurl(String menusurl) {
        this.menusurl = menusurl;
    }

    public Integer getFatherid() {
        return fatherid;
    }

    public void setFatherid(Integer fatherid) {
        this.fatherid = fatherid;
    }

    public Set<Roles> getRoles() {
        return roles;
    }

    public void setRoles(Set<Roles> roles) {
        this.roles = roles;
    }

    public Menus(String menusname, String menusurl, Integer fatherid, Set<Roles> roles) {
        this.menusname = menusname;
        this.menusurl = menusurl;
        this.fatherid = fatherid;
        this.roles = roles;
    }
}

多对多关联关系操作

package com.bjsxt.test;

import com.bjsxt.dao.RolesDao;
import com.bjsxt.pojo.Menus;
import com.bjsxt.pojo.Roles;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.Set;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class RolesTest {

    @Autowired
    private RolesDao rolesDao;

    @Test
    public void addRoles(){
        Roles roles=new Roles();
        roles.setRolename("超级管理员");

        Menus menus1=new Menus();
        menus1.setFatherid(-1);
        menus1.setMenusname("***管理系统");
        menus1.setMenusurl(null);

        Menus menus2=new Menus();
        menus2.setFatherid(1);
        menus2.setMenusname("用户管理");
        menus2.setMenusurl(null);

        roles.getMenus().add(menus1);
        roles.getMenus().add(menus2);
        menus1.getRoles().add(roles);
        menus2.getRoles().add(roles);

        rolesDao.save(roles);
    }

    @Test
    public void findall(){
        Roles roles = rolesDao.findOne(10);
        System.out.println("角色信息："+roles);
        Set<Menus> menus = roles.getMenus();
        for (Menus menu : menus) {
            System.out.println("菜单信息："+menu);

        }
    }
}