在AS3中卸載垃圾收集器的對象

Question

我在flex builder中創建了一個名爲loginInterface的對象。當這個對象被初始化時，它加載登錄界面，創建按鈕，輸入框等。

我爲這個對象創建了一個名爲unload的方法。我也有一個方法返回接口是否已經加載。現在，我想卸載對象，以便屏幕不僅可以爲新界面留出空間，而且還應該真正刪除對象，以便可以重新分配內存。

的loginInterface.as類文件：

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"); 
     } 
    } 
} 

請看看那裏的對象被加載的初始化函數和卸載功能，他們應該被卸載。這在視覺上起作用。然而，這是否是最好的方式 - 甚至會讓這些對象在一段時間後被垃圾收集器從內存中卸載？

Answer 1

當您從其父級的displayList中移除一個對象（例如LoginInterface）時，該對象內部的所有子對象也將自動從內存中移除，只要沒有包含對該對象的引用的其他對象兒童。

因此，您實際上並不需要刪除添加到LoginInterface的displayList的每個對象。您只需要移除您分配的事件偵聽器。

因此，有什麼不對你有什麼打算的，但是你真正需要你的unload方法是：

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

希望有所幫助。

Answer 2

您卸載代碼將按照您的意圖工作。 Flash垃圾回收器使用引用計數來確定特定對象是否是垃圾收集的候選對象。運行你的unload（）函數後，你在load（）中創建的所有CustomButton對象的引用計數爲0，並最終被垃圾收集。