c# - Xamarin/C# 中的 Android FileObserver 示例？

Question

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Answer 1

创建一个继承自 Android.OS.FileObserver 的类, 你只需要实现 OnEvent()和一个(+)构造函数。看过一次之后，它是一个非常简单的模式...;-)

注意事项:

• 在路径上观看，如果您需要按文件过滤，请在 OnEvent 中执行
• 不要让你的 FileObserver 对象得到 GC，否则你的 OnEvents 会神奇地停止 :-/
• 记得调用 StartWatching() 以接收 OnEvent 调用

FileObserver 类:

using System;
using Android.OS;
using Android.Util;

namespace MyFileObserver
{
    public class MyPathObserver : Android.OS.FileObserver
    {
        static FileObserverEvents _Events = (FileObserverEvents.AllEvents);
        const string tag = "StackoverFlow";

        public MyPathObserver (String rootPath) : base(rootPath, _Events)
        {
            Log.Info(tag, String.Format("Watching : {0}", rootPath)); 
        }

        public MyPathObserver (String rootPath, FileObserverEvents events) : base(rootPath, events)
        {
            Log.Info(tag, String.Format("Watching : {0} : {1}", rootPath, events)); 
        }

        public override void OnEvent(FileObserverEvents e, String path)
        {
            Log.Info(tag, String.Format("{0}:{1}",path, e)); 
        }
    }
}

示例用法:

var pathToWatch = System.Environment.GetFolderPath (System.Environment.SpecialFolder.Personal);
// Do not let myFileObserver get GC'd, stash it's ref in an activty, or ...
myFileObserver = new MyPathObserver (pathToWatch);
myFileObserver.StartWatching (); // and StopWatching () when you are done...
var document = Path.Combine(pathToWatch, "StackOverFlow.txt");
button.Click += delegate {
    if (File.Exists (document)) {
        button.Text = "Delete File";
        File.Delete (document);
    } else {
        button.Text = "Create File";
        File.WriteAllText (document, "Foobar");
    }
};

adb logcat 输出(点击测试按钮时):

I/StackoverFlow( 3596): StackOverFlow.txt:Create
I/StackoverFlow( 3596): StackOverFlow.txt:Open
I/StackoverFlow( 3596): StackOverFlow.txt:Modify
I/StackoverFlow( 3596): StackOverFlow.txt:CloseWrite
I/StackoverFlow( 3596): StackOverFlow.txt:Delete
I/StackoverFlow( 3596): StackOverFlow.txt:Create
I/StackoverFlow( 3596): StackOverFlow.txt:Open
I/StackoverFlow( 3596): StackOverFlow.txt:Modify
I/StackoverFlow( 3596): StackOverFlow.txt:CloseWrite
I/StackoverFlow( 3596): StackOverFlow.txt:Delete
I/StackoverFlow( 3596): StackOverFlow.txt:Create
I/StackoverFlow( 3596): StackOverFlow.txt:Open
I/StackoverFlow( 3596): StackOverFlow.txt:Modify
I/StackoverFlow( 3596): StackOverFlow.txt:CloseWrite