java.io.FileNotFoundException：/storage/sdcard/MyApp/questions.txt：open failed：EACCES（Permission denied）

Question

我尝试保存文件时遇到问题。首先，当我在较旧的Eclipse上尝试它时，它正常工作，但我必须使用新的Eclipse，所以我从旧的Eclipse导出项目并将其导入新的Eclipse。现在它没有保存并给我这个例外：

$('.abc').click(function(e, elem){ // alert is shown once only 

$(".custom-menu li").click(function(){ // alert is shown 3 times

我把我用来保存的代码（这个代码适用于较旧的eclipse，在new中给我异常）：

java.io.FileNotFoundException: /storage/sdcard/MyApp/questions.txt: open failed: EACCES (Permission denied)

我的清单文件：

public void saveDates(boolean mainScreen)
{

    String extr = Environment.getExternalStorageDirectory().toString();
    File mFolder = new File(extr + "/MyApp");
    if (!mFolder.exists()) 
    {
        mFolder.mkdir();
    }
    String strF = mFolder.getAbsolutePath();
    File mSubFolder = new File(strF /*+ "/MyApp-SubFolder"*/);
    if (!mSubFolder.exists()) 
    {
        mSubFolder.mkdir();
    }

    //Nombre del fichero
    String s = "questions.txt";

    BufferedWriter out;      
    try 
    {
        FileWriter fileWriter = new  FileWriter(mSubFolder.getAbsolutePath() + "/" + s, false);
        out = new BufferedWriter(fileWriter);

        out.write(indexAnswer + ";");
        out.write("\r\n");
        out.write(finished + ";");
        out.write("\r\n");
        out.write(directricesGenerales + ";");
        out.write("\r\n");
        out.write(politicaAmbiental + ";");
        out.write("\r\n");
        out.write(planificacion + ";");
        out.write("\r\n");
        out.write(implementacion + ";");
        out.write("\r\n");
        out.write(verificacion + ";");
        out.write("\r\n");
        out.write(revision + ";");
        out.write("\r\n");
        out.write(definicionProyecto + ";");
        out.write("\r\n");
        out.write(analisisAmbiental + ";");
        out.write("\r\n");
        out.write(desarrollo + ";");
        out.write("\r\n");
        out.write(disenyoDetalle + ";");
        out.write("\r\n");
        out.write(planAccion + ";");
        out.write("\r\n");
        out.write(evaluacionContinua + ";");
        out.write("\r\n");
        out.close();
    }
    catch (FileNotFoundException e) 
    {
        e.printStackTrace();
    }
    catch (IOException e) 
    {
        e.printStackTrace();
    }

    Toast.makeText(getApplicationContext(), "Datos guardados.", Toast.LENGTH_LONG).show();

    if(mainScreen)
    {
        // Cerrar la ventana de test y volver a la de inicio
        Intent intent = new Intent();

        intent.setClass(questions.this, MainActivity.class);
        startActivity(intent);
        finish();
    }
}

我的模拟器细节图片：

任何人都可以帮助我吗？我想保存文件就像我在旧版本中那样，我不知道为什么不起作用。

Answer 1

首先，您需要在清单中使用此权限才能读取文件：

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

其次，您的文件确实存在。如果没有，那么首先需要在向其写入数据之前创建文件。

如何创建文件：How to create a file in Android?

创建文件的示例代码：

// use "File.separator" instead of "/"
File file = new File(Environment.getExternalStorageDirectory() + File.separator + "test.txt");

//create the file
file.createNewFile();

//text you want to write to your file
String text = "your_text";

//check if file exists
if(file.exists()){
    OutputStream fo = new FileOutputStream(file);

    //write the data
    fo.write(text);

    //close to avoid memory leaks
    fo.close();

    //give a log message that the file was created with "text"
    System.out.println("file created: "+file);
}