Android Alarmmanager 同步

发布于 2024-10-30 23:13:44 字数 1403 浏览 1 评论 0原文

我指的是 http:// /developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/AlarmService_Service.html

线程的可运行看起来像这样

Runnable mTask = new Runnable() 
{        
    public void run() 
    {  
        Log.v("service", "thread is running after 5 min");
        // Normally we would do some work here...  for our sample, we will           
        // just sleep for 30 seconds.            
        long endTime = System.currentTimeMillis() + 15*1000;            
        while (System.currentTimeMillis() < endTime) 
        {                
            synchronized (mBinder) 
            {                    
                try 
                {                        
                    mBinder.wait(endTime - System.currentTimeMillis());      
                } 
                catch (Exception e) 
                {                    

                }                
            }            
        }            // Done with our work...  stop the service!            
        AlarmService_Service.this.stopSelf();     
    }    
}

我承认我有一些问题同步的概念...线程运行 while 循环等待 15 秒，在该循环中我等待 15 秒。那么，如果我只想编写一个日志条目，例如 Log.v(TAG,TEXT);，那么可运行程序会是什么样子？如果我想将新条目写入自己的数据库表中，会发生什么变化？

谢谢，A.

原文

I am referring to http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/AlarmService_Service.html

There the runnable of the thread looks like this

Runnable mTask = new Runnable() 
{        
    public void run() 
    {  
        Log.v("service", "thread is running after 5 min");
        // Normally we would do some work here...  for our sample, we will           
        // just sleep for 30 seconds.            
        long endTime = System.currentTimeMillis() + 15*1000;            
        while (System.currentTimeMillis() < endTime) 
        {                
            synchronized (mBinder) 
            {                    
                try 
                {                        
                    mBinder.wait(endTime - System.currentTimeMillis());      
                } 
                catch (Exception e) 
                {                    

                }                
            }            
        }            // Done with our work...  stop the service!            
        AlarmService_Service.this.stopSelf();     
    }    
}

I admit that I have some problems with the concept of synchronized... The thread runs the while loop to wait 15s, within that loop I have wait for 15s. So how would the runnable look like if I just want to write a log entry e.g. Log.v(TAG,TEXT);? What would change if I want to write a new entry into my own database table?

Thanks, A.

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余生共白头 2024-11-06 23:13:44

如果您只想要一个日志语句，那么以下内容将正常工作。

Runnable mTask = new Runnable() 
{        
    public void run() 
    {  
        Log.v("TAG", "Some verbose log message");
    }    
}

您是否需要在对象上使用同步取决于对象是否是线程安全的。如果它不是线程安全的，那么您将需要使用同步块确保一次只有一个线程访问该对象。在您的示例中，mBinder 不是线程安全的，因此为了调用绑定器的 wait 方法，您需要确保您是访问它的唯一线程。

runnable 最常用于在不同线程中执行代码，以便长时间运行的操作（例如 IO，但在本例中只是等待）不会阻塞 UI 线程。

If you just want a log statement then the following will work fine

Runnable mTask = new Runnable() 
{        
    public void run() 
    {  
        Log.v("TAG", "Some verbose log message");
    }    
}

Whether you need to use synchronized on an object depends on whether object is thread-safe or not. If it is not thread-safe, then you will need to ensure that only one thread access the object at a time by using a synchronized block. In your example mBinder is not thread-safe, so in order to call the wait method of the binder you need to ensure that you are the only thread accessing it.

A runnable is most often used to execute code in a different thread, so that long running operations (such as IO, but in this case just waiting) do not block the UI thread.

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