具有参数的单例枚举枚举实现 [英] Singleton Enum implementation with parameters

问题描述

但是，当我第一次初始化时，我也希望将一些参数传递给构造函数。 / p>

如何实现？有单参加参数的做法是一个好习惯吗？

  public enum DaoManager {
 INSTANCE; 
私有静态ILog记录器; //通过记录器
私有静态DatabasePool池; //传递数据库池
 
 public void init（ILog logger，DatabasePool pool）{
 this.logger = logger; 
 this.pool = pool; 
} 
 
} 
  

现在我正在使用一个init将记录器和数据库池传递给DaoManager的方法。

但如果客户端无法调用init（）方法，那么很有可能失败。

有人可以指导我怎么做？

解决方案

我可以使init方法私有吗？

如果对象存在所需的某种初始化逻辑一个有效的状态。那么应该有一个工厂，当一个对象被请求的时候这样做。

有一个 static init 不好的设计。

使用Singleton的BTW更适用于测试。有一个全局状态使对象难以测试。

你不应该限制构造函数，而是使对象 singleton 。使用某种上下文对象来获取应用程序的单一实例 DaoManager 。

  applicationContext.getDaoManager（）
  

I am trying to implement a Singleton with Java enum.

But I also want to pass some parameters to the constructor when it is initialized for the first time.

How do I achieve that? Is it a good practice to have Singletons with parameter?

public enum DaoManager {
    INSTANCE;
    private static ILog logger; //for passing the logger;
    private static DatabasePool pool; //passing the Database pool

    public void init(ILog logger, DatabasePool pool){
          this.logger = logger;
          this.pool = pool;   
    }

 }

Right now I am using a init method to pass the logger and database pool to DaoManager.

But if client fails to invoke the init() method then there a good chance of failure.

Can someone please guide me on how do I do this?

解决方案

Can I make the init method private?

If there is some kind of initialization logic required for the object to be in a valid state. Then there should be a factory which does this when an object is requested to it.

Having a static init is bad design.

BTW using Singleton is more an anti-pattern for testing. Having a global state makes the object hard to test.

You should not restrict the constructor but make the object singleton with a small 's'. Use some kind of a context object to get the access of the application wide single instance of the DaoManager.

applicationContext.getDaoManager()

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