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);

        }

    }

}