android - 安卓SD卡读取

Question

我在 Android 上有一个应用程序，它在系统启动时启动。有时互联网连接处于搜索模式，我设置了一个计时器来检查连接，如果找到则连接。我为 sd 卡做了同样的事情，因为它也处于准备模式。当系统启动和应用程序启动时，我在从 sd 卡读取文本文件时遇到问题，它从不从 sd 卡读取文本。当我稍后手动启动该应用程序时，它可以工作。这是我读取 sd 卡文件的代码。

 if (isSDCardAvailable())
            {
                setTickerText();
            }

    else if(!isSDCardAvailable())
            {
                //pop up message
                Toast toast=Toast.makeText(this, "Preparing SD card..", Toast.LENGTH_LONG);
                toast.show();

                //Run the sd card read process after 30 seconds
                Handler handler = new Handler(); 
                handler.postDelayed(new Runnable() { 
                     public void run() 
                     { 
                         setTickerText();
                     } 
                }, 30000);
            }

 public void setTickerText()
{
    File sdcard = Environment.getExternalStorageDirectory();

    //Get the text file
    File file = new File(sdcard,"TickerText.txt");

    //Read text from file
    StringBuilder text = new StringBuilder();

    try {
        BufferedReader br = new BufferedReader(new FileReader(file));
        String line;

        while ((line = br.readLine()) != null) {
            text.append(line);
            //text.append('\n');
        }
    }
    catch (IOException e) {
        //You'll need to add proper error handling here
    }
       }

Answer 1

编译系统启动后，您的应用程序开始读取文件。

所以在此之前你可以这样检查：

static public boolean hasStorage(boolean requireWriteAccess) {
    //TODO: After fix the bug,  add "if (VERBOSE)" before logging errors.
    String state = Environment.getExternalStorageState();
    Log.v(TAG, "storage state is " + state);

    if (Environment.MEDIA_MOUNTED.equals(state)) {
        if (requireWriteAccess) {
            boolean writable = checkFsWritable();
            Log.v(TAG, "storage writable is " + writable);
            return writable;
        } else {
            return true;
        }
    } else if (!requireWriteAccess && Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        return true;
    }
    return false;
}