java - 使用android存储文件和文件夹

Question

我正在开发一个移动应用程序，我将在其中将生成的值保存到文件中。我已存储在文件中，文件也保存在文件夹中。但是从应用程序退出后，当我打开文件并尝试读取值时，它不读取文件。事实上，文件存储在设备内存中而不是外部设备中。我已在 list 文件中授予权限。

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

这里我附上我的代码。请指导我我犯了什么错误。//这里我存储两个数据

public void setData(String newData , String newTime , String fileName) throws JSONException {
  try { 
  //FileOutputStream fou = openFileOutput("text.txt", MODE_WORLD_READABLE);  
  File sdcard = android.os.Environment.getExternalStorageDirectory();  
  File directory = new File(sdcard.getAbsolutePath()+ "/MyDirectory");  
  directory.mkdirs();  
  File file = new File(directory,fileName);  
  FileOutputStream fou = new FileOutputStream(file , true);  
  OutputStreamWriter osw = new OutputStreamWriter(fou);  
  try {  
  osw.write(String.valueOf(newData));
  osw.append(',');
  osw.write(String.valueOf(newTime));
  osw.write(System.lineSeparator());
  osw.close();  
  } catch (IOException e) {  
  // TODO Auto-generated catch block  
  e.printStackTrace();  
  }  
  } catch (FileNotFoundException e) {  
  // TODO Auto-generated catch block  
  e.printStackTrace();  
  }  
  }

//这里我正在读取移动设备中保存的文件内容

  @TargetApi(Build.VERSION_CODES.KITKAT)
  @JavascriptInterface
  public String ReadFile(String fileName)
  {
  String content;
  ArrayList<String> arr = new ArrayList<String>();
  //int linenumber = 0;
  File sdcard = android.os.Environment.getExternalStorageDirectory();  
  File directory = new File(sdcard.getAbsolutePath()+ "/MyDirectory");  
  //File directory = new File(sdcard.getAbsolutePath()+ "/MyDirectory");
  //File f = new File("");
  Log.d(TAG, "acrd checking called");
  System.out.println(sdcard.getAbsolutePath());
  File file = new File(directory,fileName);  
  try (InputStream fis = new FileInputStream(file)) {
  BufferedReader br=new BufferedReader(new InputStreamReader(fis));
  //char stringComma = new Character(',');
  while ((content = br.readLine()) != null) {
  // convert to char and display it
  Log.d(TAG, "called");
  arr.add(content);
  Log.d(TAG, "called");
  System.out.println(arr);
  }
  br.close();  
  } 
  catch (IOException e) {
  e.printStackTrace();
  }
  return arr.toString();
  }

可能出现什么问题？

Answer 1

完成写入后，您应该关闭输出流，例如fou.close()