java - 使用 hibernate 注释关联两个表

Question

我是Hibernate新手，所以如果问题重复或愚蠢，请原谅我。我正在使用 Hibernate 3.3.0、PostgreSQL 数据库。现在我有2个实体。我需要将它们与@OneToMany注释关联起来，User.roleID是PK，Role.id是FK(用户只能拥有一个角色，相同的角色可以分配给多个用户)。另外，当我在 Google 中搜索时，我发现由于某种原因，每个带有注释关联的示例都有声明为 Set 的注释字段。请向我解释一下。谢谢您的建议。

纳扎尔。

用户实体:

package com.dataart.mediaportal.model;

import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;


@Entity
@Table(name = "users")
public class User implements Serializable {

    private int id;
    private String login;
    private String password;
    private String firstName;
    private String lastName;
    private int roleID;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "user_id", unique = true)
    public int getId() {
        return id;
    }

    @Column(name = "user_login", nullable=false, unique = true, length = 20 )
    public String getLogin() {
        return login;
    }

    @Column(name = "user_password", nullable = false, length = 32)
    public String getPassword() {
        return password;
    }

    @Column(name = "user_name", nullable = true)
    public String getFirstName() {
        return firstName;
    }

    @Column(name = "user_lastname", nullable = true)
    public String getLastName() {
        return lastName;
    }

    @Column(name = "role_id", nullable = false)
    public int getRoleID() {
        return roleID;
    }

    public void setRoleID(int roleID) {
        this.roleID = roleID;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public void setFirstName(String firstname) {
        this.firstName = firstname;
    }

    public void setLastName(String lastname) {
        this.lastName = lastname;
    }
}

角色实体:

package com.dataart.mediaportal.model;

import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;


@Entity
@Table(name = "roles")
public class Role implements Serializable {

    private int id;
    private String role;

    @Id
    @Column(name = "role_id", nullable = false)
    public int getId() {
        return id;
    }

    @Column(name = "role_name", nullable = false)
    public String getRole() {
        return role;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setRole(String role) {
        this.role = role;
    }

}

数据库脚本:

DROP TABLE IF EXISTS users CASCADE;
DROP TABLE IF EXISTS roles CASCADE;
DROP TABLE IF EXISTS albums CASCADE;
DROP TABLE IF EXISTS images CASCADE;

CREATE TABLE users
(
  user_login character varying(20) NOT NULL,
  user_password character varying(32) NOT NULL,
  user_name character varying,
  user_lastname character varying,
  role_id integer DEFAULT 0,
  user_id serial NOT NULL,
  CONSTRAINT pk_user_id PRIMARY KEY (user_id),
  CONSTRAINT users_user_login_key UNIQUE (user_login)
)
WITH (
  OIDS=FALSE
);
ALTER TABLE users
  OWNER TO postgres;

CREATE TABLE roles
(
  role_id integer NOT NULL,
  role_name character varying NOT NULL DEFAULT 'user'::character varying,
  CONSTRAINT role_id_pk PRIMARY KEY (role_id)
)
WITH (
  OIDS=FALSE
);
ALTER TABLE roles
  OWNER TO postgres;

INSERT INTO roles
VALUES ( 0, 'user' ),
( 1, 'admin' );

-- testlog - testpass
-- user - password
INSERT INTO users
VALUES ( 'testlog', '179ad45c6ce2cb97cf1029e212046e81', 'Nazar', 'Sobchuk', 1),
('user', '5f4dcc3b5aa765d61d8327deb882cf99', 'unknown', 'unknown', 0);


CREATE TABLE albums
(
  album_name character varying NOT NULL,
  user_id integer,
  album_id serial NOT NULL,
  CONSTRAINT album_id PRIMARY KEY (album_id),
  CONSTRAINT user_id FOREIGN KEY (user_id)
      REFERENCES users (user_id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION
)
WITH (
  OIDS=FALSE
);
ALTER TABLE albums
  OWNER TO postgres;
CREATE INDEX fki_user_id
  ON albums
  USING btree
  (user_id);

INSERT INTO albums VALUES ('Main Album', 1);

CREATE TABLE images
(
  img bytea,
  img_name character varying NOT NULL,
  album_id integer,
  img_id serial NOT NULL,
CONSTRAINT images_img_name UNIQUE(img_name),
  CONSTRAINT album_id FOREIGN KEY (album_id)
      REFERENCES albums (album_id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION

)
WITH (
  OIDS=FALSE
);
ALTER TABLE images
  OWNER TO postgres;

CREATE INDEX fki_album_id
  ON images
  USING btree
  (album_id);

插入用户:

public boolean insertUser(User user) {
    factory = getSessionFactory();
    session = factory.openSession();
    tx = session.beginTransaction();
    Query queryResult = session.createQuery("from User");
    List<User> userList = queryResult.list();
    for (User u : userList) {
        if (u.getLogin().equalsIgnoreCase(user.getLogin())) {
            FacesContext.getCurrentInstance().addMessage(null,
                    new FacesMessage("User_is_already_registered"));
            return false;
        }
    }
    session.save(user);
    tx.commit();
    session.close();
    return true;
}

Answer 1

将用户作为一对多关系添加到角色，如下所示。也创 build 置器

private List<User> userList;
    @OneToMany(mappedBy = "role")
    public List<User> getUserList() {
        return userList;
    }

将角色添加到用户的多对一关系，如下所示

private Role role;
    @ManyToOne
    public Role getRole() {
        return role;
    }