获取文件未找到异常

Question

我有我的安卓活动：

try {  
            File root=Environment.getExternalStorageDirectory();  
            Log.i("root",root.toString());  
                            File dir=new File(root.getAbsolutePath() + "/downloads");  
            dir.mkdirs();  
            file=new File(dir,"mytext.txt");  
            FileOutputStream out=new FileOutputStream(file,true);  
            PrintWriter pw=new PrintWriter(out);  
            pw.println("Hello! Welcome");  
            pw.println("You are Here...!!!");  
            pw.flush();  
            pw.close();  
            try {  
                 out.close();  
            } catch (IOException e) {  
            // TODO Auto-generated catch block  
                e.printStackTrace();  
          }
        } catch (FileNotFoundException e) {  
             // TODO Auto-generated catch block  
             e.printStackTrace();
        }  

还添加了：

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

但它会抛出 FileNotfound 异常： 01-13 09:06:44.442: WARN/System.err(419): java.io.FileNotFoundException: /mnt/sdcard/downloads/mytext.txt（没有这样的文件或目录）

如果我添加

 if(file.exists()){  
   System.out.println("file exists");  
  }  
  else{  
     System.out.println("No such Fileeeeeeeeee");  
   }  

它进入“其他”部分。

谢谢
斯内哈

Answer 1

试试这个，它对我有用

// create a File object for the parent directory
File wallpaperDirectory = new File("/sdcard/Wallpaper/");
// have the object build the directory structure, if needed.
wallpaperDirectory.mkdirs();
// create a File object for the output file
File outputFile = new File(wallpaperDirectory, filename);
//now attach OutputStream to the file object, instead of a String representation

FileOutputStream fos = new FileOutputStream(outputFile);

GO through this for more details

Answer 2

在 Android 6 (Marshmallow) 中，我必须明确检查我的应用是否有权限 "WRITE_EXTERNAL_STORAGE"

Answer 3

不确定，但请确认您的模拟器或手机中存在外部存储，否则会出现异常。