SpringDataJPA之关联关系

  本文介绍下SpringDataJPA怎么处理关联关系

关联关系处理

1.一对一

  用户和角色设置一对一关系，通过外键关联。

pojo设置

创建 Users 实体

代码语言：javascript复制

@Entity
@Table(name="t_users")
public class Users implements Serializable{
	@Id
	//strategy=GenerationType.IDENTITY 自增长
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="userid")
	private Integer userid;
	
	@Column(name="username")
	private String username;
	
	@Column(name="userage")
	private Integer userage;
	
	public Roles getRoles() {
		return roles;
	}
	public void setRoles(Roles roles) {
		this.roles = roles;
	}
	@OneToOne
	//@JoinColumn：就是维护一个外键
	@JoinColumn(name="roles_id")
	private Roles roles;
	
	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;
	}
	@Override
	public String toString() {
		return "Users [userid="   userid   ", username="   username   ",userage="   userage   "]";
	}
}

创建 Roles 实体

代码语言：javascript复制

@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;
	public Users getUsers() {
		return users;
	}
	public void setUsers(Users users) {
		this.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;
	}
}

关联关系操作

代码语言：javascript复制

/**
* 一对一关联关系测试
* @author Administrator
*
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class OneToOneTest {
	@Autowired
	private UsersDao usersDao;
	/**
	* 添加用户同时添加角色
	*/
	@Test
	public void test1(){
		//创建角色
		Roles roles = new Roles();
		roles.setRolename("管理员");
		//创建用户
		Users users = new Users();
		users.setUserage(30);
		users.setUsername("赵小刚");
		//建立关系
		users.setRoles(roles);
		roles.setUsers(users);
		//保存数据
		this.usersDao.save(users);
	}
	/**
	* 根据用户 ID 查询用户，同时查询用户角色
	*/
	@Test
	public void test2(){
		Users users = this.usersDao.findOne(13);
		System.out.println("用户信息：" users);
		Roles roles = users.getRoles();
		System.out.println(roles);
	}
}

2.一对多

从角色到用户的一对多的关联关系 角色：一方 用户：多方

pojo

代码语言：javascript复制

@Entity
@Table(name="t_users")
public class Users implements Serializable{
	@Id
	//strategy=GenerationType.IDENTITY 自增长
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="userid")
	private Integer userid;
	
	@Column(name="username")
	private String username;
	
	@Column(name="userage")
	private Integer userage;
	
	@ManyToOne()
	@JoinColumn(name="roles_id")
	private Roles roles;
	
	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;
	}
	@Override
	public String toString() {
		return "Users [userid="   userid   ", username="   username   ",userage="   userage   "]";
	}
}

代码语言：javascript复制

@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;
	
	@OneToMany(mappedBy="roles")
	private Set<Users> users = new HashSet<>();
	
	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;
	}
	@Override
	public String toString() {
		return "Roles [roleid="   roleid   ", rolename="   rolename   "]";
	}
}

操作

代码语言：javascript复制

/**
* 一对多的关联关系测试
* @author Administrator
*
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class OneToManyTest {
@Autowired
private UsersDao usersDao;
	/**
	* 添加用户同时添加角色
	*/
	@Test
	public void test1(){
		//创建角色
		Roles roles = new Roles();
		roles.setRolename("管理员");
		//创建用户
		Users users =new Users();
		users.setUserage(30);
		users.setUsername("小王");
		//建立关系
		roles.getUsers().add(users);
		users.setRoles(roles);
		//保存数据
		this.usersDao.save(users);
	}
	/**
	* 根据用户 ID 查询用户信息，同时查询角色
	*/
	@Test
	public void test2(){
		Users users = this.usersDao.findOne(14);
		System.out.println("用户姓名：" users.getUsername());
		Roles roles = users.getRoles();
		System.out.println(roles);
	}
}

3.多对多

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

Pojo

代码语言：javascript复制

@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
	//@JoinTable:配置中间表信息
	//joinColumns:建立当前表在中间表中的外键字段
	@JoinTable(name="t_roles_menus",joinColumns=@JoinColumn(name="role_id"),inverseJoinColumns=@JoinColumn(name="menu_id"))
	private Set<Menus> menus = new HashSet<>();
	
	public Set<Menus> getMenus() {
		return menus;
	}
	public void setMenus(Set<Menus> menus) {
		this.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;
	}
	@Override
	public String toString() {
		return "Roles [roleid="   roleid   ", rolename="   rolename   "]";
	}
}

代码语言：javascript复制

@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 Set<Roles> getRoles() {
		return roles;
	}
	public void setRoles(Set<Roles> roles) {
		this.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;
	}
	@Override
	public String toString() {
		return "Menus [menusid="   menusid   ", menusname="   menusname  ", menusurl="   menusurl   ", fatherid="  fatherid   "]";
	}
}

操作

代码语言：javascript复制

/**
* 多对多关联关系测试
* @author Administrator
*
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class ManyToManyTest {
	@Autowired
	private RolesDao rolesDao;
	/**
	* 添加角色同时添加菜单
	*/
	@Test
	public void test1(){
		//创建角色对象
		Roles roles = new Roles();
		roles.setRolename("超级管理员");
		//创建菜单对象 XXX 管理平台 --->用户管理
		Menus menus = new Menus();
		menus.setMenusname("XXX 管理平台");
		menus.setFatherid(-1);
		menus.setMenusurl(null);
		//用户管理菜单
		Menus menus1 = new Menus();
		menus1.setMenusname("用户管理");
		menus1.setFatherid(1);
		menus1.setMenusurl(null);
		//建立关系
		roles.getMenus().add(menus);
		roles.getMenus().add(menus1);
		menus.getRoles().add(roles);
		menus1.getRoles().add(roles);
		//保存数据
		this.rolesDao.save(roles);
	}
	/**
	* 查询 Roles
	*/
	@Test
	public void test2(){
		Roles roles = this.rolesDao.findOne(3);
		System.out.println("角色信息：" roles);
		Set<Menus> menus = roles.getMenus();
		for (Menus menus2 : menus) {
			System.out.println("菜单信息：" menus2);
		}
	} 
}

pojo

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