在AS3中卸载垃圾收集器的对象

Question

我在flex builder中创建了一个名为loginInterface的对象。当这个对象被初始化时，它加载登录界面，创建按钮，输入框等。

我为这个对象创建了一个名为unload的方法。我也有一个方法返回接口是否已经加载。现在，我想卸载对象，以便屏幕不仅可以为新界面留出空间，而且还应该真正删除对象，以便可以重新分配内存。

的loginInterface.as类文件：

package 
{ 
    //import required libraries 
    import flash.display.Sprite; 
    import flash.events.MouseEvent; 
    import flash.net.URLRequest; 
    import flash.net.navigateToURL; 

    public class LoginInterface extends Sprite 
    { 
     private var welcomeLabel:CustomLabel; 
     private var versionLabel:CustomLabel; 
     private var loginButton:CustomButton; 
     private var registerButton:CustomButton; 
     private var usernameLabel:CustomLabel; 
     private var passwordLabel:CustomLabel; 
     private var usernameInputBox:CustomInputBox; 
     private var passwordInputBox:CustomInputBox; 
     private var loaded:Boolean = false; 

     public function LoginInterface() 
     { 
      trace("LoginInterface object loaded."); 
      init(); //initialize the login interface 
     } 

     public function init():void //initialize the login interface 
     { 
      trace("LoginInterface init method was called."); 

      //create objects 
      welcomeLabel = new CustomLabel(200, 100, 500, 30, "Welcome to the ALPHA client."); //welcome label 
      versionLabel = new CustomLabel(200, 120, 500, 30, "Version: v1.0.000", "Arial", 0x000000, 12); //version label 
      loginButton = new CustomButton(300, 300, 100, 30, "Login"); //login button 
      registerButton = new CustomButton(400, 300, 100, 30, "Register") //register button   
      usernameLabel = new CustomLabel(200, 200, 200, 30, "username: "); //username label  
      passwordLabel = new CustomLabel(200, 240, 200, 30, "password: "); //password label 
      usernameInputBox = new CustomInputBox(300, 200, 200, 30, false, 0x6D7B8D); //username input box 
      passwordInputBox = new CustomInputBox(300, 240, 200, 30, true, 0x6D7B8D); //password input box 

      //add objects to the display tree 
      addChild(welcomeLabel); 
      addChild(versionLabel); 
      addChild(loginButton); 
      addChild(registerButton); 
      addChild(usernameInputBox); 
      addChild(usernameLabel); 
      addChild(passwordInputBox); 
      addChild(passwordLabel); 

      //register object events 
      registerButton.addEventListener(MouseEvent.CLICK, registerClicked); //register button is clicked 
      loginButton.addEventListener(MouseEvent.CLICK, loginClicked); //login button is clicked 

      //interface has been loaded 
      loaded = true; 
     } 

     public function isLoaded():Boolean 
     { 
      if (loaded) return true; 
      return false; 
     } 

     public function unload():void 
     { 
      if (!loaded) return; 
      //welcomeLabel 
      removeChild(welcomeLabel); 
      welcomeLabel = null; 
      //versionLabel 
      removeChild(versionLabel); 
      versionLabel = null; 
      //loginButton 
      loginButton.removeEventListener(MouseEvent.CLICK, loginClicked); 
      removeChild(loginButton); 
      loginButton = null; 
      //registerButton 
      registerButton.removeEventListener(MouseEvent.CLICK, registerClicked); 
      removeChild(registerButton); 
      registerButton = null; 
      //usernameInputBox 
      removeChild(usernameInputBox); 
      usernameInputBox = null; 
      //usernameLabel 
      removeChild(usernameLabel); 
      usernameLabel = null; 
      //passwordInputBox 
      removeChild(passwordInputBox); 
      passwordInputBox = null; 
      //passwordLabel 
      removeChild(passwordLabel); 
      passwordLabel = null; 
      //set loaded to false 
      loaded = false; 
     } 

     private function loginClicked(event:MouseEvent):void 
     { 
      trace("Login button has been clicked."); 
      var username:String = usernameInputBox.text; 
      var password:String = passwordInputBox.text; 
      if (!checkLogin(username, password)) { 
       new Alert("Please enter a correct username and password."); 
      } 
      else { 
       trace("Creating socket connection."); 
       var socketConnection:SocketConnection = new SocketConnection(this); 
      } 
     } 

     private function checkLogin(username:String, password:String):Boolean 
     { 
      if ((username == "") || (password == "")) { 
       return false; 
      } 
      return true; 
     } 

     private function registerClicked(event:MouseEvent):void 
     { 
      trace("Register button has been clicked."); 
      var url:URLRequest = new URLRequest("http://url.com/client/register.php"); 
      navigateToURL(url, "_blank"); 
     } 
    } 
} 

请看看那里的对象被加载的初始化函数和卸载功能，他们应该被卸载。这在视觉上起作用。然而，这是否是最好的方式 - 甚至会让这些对象在一段时间后被垃圾收集器从内存中卸载？

Answer 1

当您从其父级的displayList中移除一个对象（例如LoginInterface）时，该对象内部的所有子对象也将自动从内存中移除，只要没有包含对该对象的引用的其他对象儿童。

因此，您实际上并不需要删除添加到LoginInterface的displayList的每个对象。您只需要移除您分配的事件侦听器。

因此，有什么不对你有什么打算的，但是你真正需要你的unload方法是：

loginButton.removeEventListener(MouseEvent.CLICK, loginClicked); 
registerButton.removeEventListener(MouseEvent.CLICK, registerClicked); 

希望有所帮助。

Answer 2

您卸载代码将按照您的意图工作。 Flash垃圾回收器使用引用计数来确定特定对象是否是垃圾收集的候选对象。运行你的unload（）函数后，你在load（）中创建的所有CustomButton对象的引用计数为0，并最终被垃圾收集。