如何防止GUI在多线程中互相干扰

Question

我一直是用Java处理图像的程序。然而，在这个图像处理过程中，同时运行的同时（包括进度条等）的swing GUI会冻结，直到处理完成。我试过多线程程序来解决这个问题，让处理在后台运行，但它似乎不工作。

下面是我一直在使用的一些代码。

public class GUIThread implements Runnable { 
    public static final int CHOOSER_HUB = 0; 
    public static final int LAUNCH_IMAGE_PREVIEWER = 1; 
    public static final int DISABLE_PREVIEWER_BUTTONS = 2; 
    public static final int MEMORY_USAGE_WINDOW = 3; 
    private int guiNumber; 

    // ========================================================================== 
    // |        START CODE        | 
    // ========================================================================== 

    /** 
    * Runs begins the thread. This method is also for pre-run configuration, 
    * but so far there is none of that. 
    * 
    * @param GUINumber 
    *   The GUI number, indicating which GUI to start. 
    */ 
    public void start(int GUINumber) { 
     DebugMessenger.out("Starting new thread for GUI"); 
     guiNumber = GUINumber; 
     run(); 
    } 

    /** 
    * Starts the thread, and runs a method determined by what guiNumber was set. 
    */ 
    @Override 
    public void run() { 
     DebugMessenger.out("Thread running"); 
     if (guiNumber == GUIThread.CHOOSER_HUB) 
      createChooserHub(); 
     if (guiNumber == GUIThread.LAUNCH_IMAGE_PREVIEWER) 
      createPreviewer(); 
     if (guiNumber == GUIThread.DISABLE_PREVIEWER_BUTTONS) 
      disablePreviewerButtons(); 
     if (guiNumber == GUIThread.MEMORY_USAGE_WINDOW) 
      createMemoryUsageWindow(); 
    } 

    /* More code, including methods called by run() */ 

} 

要启动我的程序，我只需运行以下代码。

public class Main { 
    /** 
    * Main method. Starts the threads and lets them roll. 
    * @param args 
    */ 
    public static void main(String[] args) { 
     // start threads 
     DebugMessenger.out("Starting Main"); 
     GUIThread guiThread = new GUIThread(); 
     guiThread.start(GUIThread.LAUNCH_IMAGE_PREVIEWER); 
     if(Config.DEBUG_OUTPUT_ENABLED) { 
      memBarThread = new GUIThread(); 
      memBarThread.start(GUIThread.MEMORY_USAGE_WINDOW); 
     } 
     DebugMessenger.out("Main complete"); 
    } 
} 

正如你所看到的，我做了关于尽可能简单的多线程，但它似乎仍然是，当我运行程序和图像预览开始处理，内存使用率窗口冻结。我怎样才能防止这一点？

Answer 1

你的代码中缺少一个重要的东西，它将成为瓶颈，在Java中，你从来不会自己调用run（）（如果你这样做，它不会创建一个单独的线程，而是运行在主线程本身），而将创建一个Thread对象，并开始如低于Thread（使用启动方法），这样它会调用在一个单独的线程的run（）方法，如下所示：

GUIThread类：

public class GUIThread implements Runnable { 
    public static final int CHOOSER_HUB = 0; 
    public static final int LAUNCH_IMAGE_PREVIEWER = 1; 
    public static final int DISABLE_PREVIEWER_BUTTONS = 2; 
    public static final int MEMORY_USAGE_WINDOW = 3; 
    private int guiNumber; 


    public void setGUINumber(int GUINumber) { 
     this.guiNumber = GUINumber; 
    } 

    @Override 
    public void run() { 
     DebugMessenger.out("Thread running"); 
     if (guiNumber == GUIThread.CHOOSER_HUB) 
      createChooserHub(); 
     if (guiNumber == GUIThread.LAUNCH_IMAGE_PREVIEWER) 
      createPreviewer(); 
     if (guiNumber == GUIThread.DISABLE_PREVIEWER_BUTTONS) 
      disablePreviewerButtons(); 
     if (guiNumber == GUIThread.MEMORY_USAGE_WINDOW) 
      createMemoryUsageWindow(); 
    } 

    /* More code, including methods called by run() */ 

} 

主类：

public class Main { 
    /** 
    * Main method. Starts the threads and lets them roll. 
    * @param args 
    */ 
    public static void main(String[] args) { 
     // start threads 
     DebugMessenger.out("Starting Main"); 

     GUIThread guiThread = new GUIThread(); 
     guiThread. setGUINumber(GUIThread.LAUNCH_IMAGE_PREVIEWER); 

     //Create and Start the Thread now using Thread API 
     Thread threadObj = new Thread(guiThread).start(); 

     if(Config.DEBUG_OUTPUT_ENABLED) { 
      memBarThread = new GUIThread(); 
      memBarThread.start(GUIThread.MEMORY_USAGE_WINDOW); 
     } 
     DebugMessenger.out("Main complete"); 
    } 
} 

可以here

Answer 2

您没有使用多线程在所有与您所提供的代码看起来。

您从调用GUIThread.start(int)开始，不管这个调用run()这是什么输入，我猜是阻塞工作的方法。没有一个新的线程被创建并被告知开始独立执行。

我建议你考虑以下概念：

• 并发Swing和事件调度循环：https://docs.oracle.com/javase/tutorial/uiswing/concurrency/index.html
• 执行人：https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/Executors.html
• 主题：https://docs.oracle.com/javase/tutorial/essential/concurrency/runthread.html

Answer 3

你的GUI冻结因为这些操作仍在Swing GUI线程中运行。

让GUIThread类扩展Thread（而不是执行Runnable）并调用线程的start方法。