Setting up a One To ManyJoins Against a Bridge Table using JPA

Am new to JPA...

I have the following preexisting tables inside a MySQL 5 database:

• App


• User


• User_App_Bridge

The relationship(s) are mapped to the User_App_Bridge table (as the name implies, a bridge) amongst App and User as a One to Many cardinality.

The E-R diagram:

User ------ User_App_Bridge------ App

1 User is associated with many apps inside the User_App_Bridge table.

1 App is associated with many users inside the User_App_Bridge table.

The DDL for the User_App_Bridge table:

CREATE TABLE `User_App_Bridge` (
    `User_App_Bridge_Id` int(11) NOT NULL AUTO_INCREMENT,
    `User_Id` int(11) NOT NULL,
    `App_Id` int(11) NOT NULL,
    PRIMARY KEY (`User_App_Bridge_Id`),
    KEY `App_Id` (`App_Id`),
    KEY `User_Id` (`User_Id`),
    CONSTRAINT `user_app_bridge_ibfk_1` FOREIGN KEY (`App_Id`) REFERENCES `App` (`App_Id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Lets say that I have the following JPA Annotated Classes which are mapped to these tables:

@Entity
public class App {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "App_Id")
    private long appId;

    @OneToMany
    @JoinTable
    (
        name = "UserAppBridge",
        joinColumns = { @JoinColumn(name="App_Id", referencedColumnName = "App_Id") },
        inverseJoinColumns = { @JoinColumn(name="User_Id", referencedColumnName = "User_Id") }
    )
    private List<User> users;

    @Column(name = "App_Name")
    private String appName;

    // Getters & Setter methods
}

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "User_Id")
    private long userId;

    @OneToMany
    @JoinTable
    (   
       name = "UserAppBridge",
       joinColumns = { @JoinColumn(name="User_Id", referencedColumnName = "User_Id") },
       inverseJoinColumns = { @JoinColumn(name="App_Id", referencedColumnName = "App_Id", unique = true) }
    )
    private List<App> apps;

    @Column(name = "User_Name")
    private String userName;

    // Getters & Setter methods
}

@Entity
public class UserAppBridge {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "User_App_Bridge_Id")
    private long userAppBridgeId;

    @Column(name = "User_Id")
    private long userId;

    @Column(name = "App_Id")
    private long appId;

    // Getters & Setter methods
}

Question(s):

1. 
   

   Is this (the block inside the @JoinTable) the correct way to do the one to many mapping for User and App entites with the UserAppBridge?

   
   


2. 
   

   Inside the @JoinTable should the column & referencedColumnName be assigned to the SQL value (e.g. name="User_Id" , referencedColumnName = "User_Id") or should it be the Java reference name (e.g. name="userId" , referencedColumnName = "userId")?

   
   


3. 
   

   Inside the inverseJoinColumns code black, is the unique = true necessary (what is it for)?

   
   


4. 
   

   Do I need to do anything else inside the UserAppBridge class (for connecting to App and User)?

   
   

Thank you for taking the time to read this...