从SD卡读取文件

Question

我已将文件“ecg.text”放入目录 mnt/sdcard/ecg/ecg.text 中，然后使用以下代码来读取它，但不断捕获（FileNotFoundException）。任何有关如何查找该文件的帮助或建议将不胜感激。

提前致谢。

主要活动类：

ECGFilereader reader;

    try {
        reader = new ECGFilereader("ecg");
        reader.ReadFile(waves);

        for (int chan=0; chan<ECGFilereader.numChannels; chan++) {
            waves[chan].drawSignal(c, (wavePos[chan])); //new Waveform may need to be created
        }

    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

和 ECGFilereader.java

public class ECGFilereader {  

public final static int numChannels = 12;   // the data is stored in 12 channels, one for each lead
public final static int numSamples = 500*6; //500 = fs so *6 for 6 seconds of data
public File file;
private Scanner scanner;
short [] [] ecg = new short [numChannels] [numSamples];

 public ECGFilereader (String fname) throws FileNotFoundException 
 {
    File dir = Environment.getExternalStorageDirectory();       //accesses the ecg file from the SD card
    file = new File(dir, "mnt/sdcard/ecg/ecg.text");
    scanner = new Scanner(file);
}
public boolean ReadFile(Waveform[] waves) // sorts data into and array of an array (12 channels each containing 5000 samples)
{
    for (int m=0; m<numSamples && scanner.hasNextInt(); m++)
    {
        int x = scanner.nextInt();
        for (int chan = 0; chan<numChannels && scanner.hasNextInt(); chan++)
        {
            ecg [chan] [m] = (short) scanner.nextInt();     
        }
    }

    for (int chan=0; chan<numChannels; chan++)
        waves[chan].setSignal(ecg[chan]); // sets a signl equal to the ecg array of channels
    return true;

}

}

Answer 1

确保您在 AndroidManifest.xml 中拥有正确的权限。
我相信是：

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Answer 2

您是否尝试过 file = new File(dir, "ecg/ecg.text"); ？

但是，我不明白为什么当您甚至没有从磁盘读取文件时（您刚刚创建了一个新的 File 对象），您会收到 FileNotFoundException 。您是否忘记上传某些代码？

HTH，

阿克谢