Android SD卡內的文件讀寫操作

private String readFromFile(Context context){


    if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {

        String foldername = Environment.getExternalStorageDirectory().getPath()+ "/eryaApp";
        File folder = new File(foldername);

        if (folder == null || !folder.exists()) {
            folder.mkdir();
        }

        File targetFile=new File("/sdcard/eryaApp/eryaShoppingList.txt");
        String readedStr="";

         try{
            if(!targetFile.exists()){
                targetFile.createNewFile();
                return "No File error ";
            }else{
                 InputStream in = new BufferedInputStream(new FileInputStream(targetFile));
                 BufferedReader br= new BufferedReader(new InputStreamReader(in, "UTF-8"));
                 String tmp;

                 while((tmp=br.readLine())!=null){
                     readedStr+=tmp;
                 }
                 br.close();
                 in.close();

                 return readedStr;
            }
         } catch (Exception e) {
                Toast.makeText(context,e.toString(),Toast.LENGTH_LONG).show();
                return e.toString();
         }
    }else{
        Toast.makeText(context,"未發現SD卡！",Toast.LENGTH_LONG).show();
        return "SD Card error";
    }

}</pre> 



private void SavedToText(Context context,String stringToWrite){


    if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {

        String foldername = Environment.getExternalStorageDirectory().getPath()+ "/eryaApp";
        File folder = new File(foldername);

        if (folder == null || !folder.exists()) {
            folder.mkdir();
        }

        String fileName="/eryaShoppingList"+".txt";

        File targetFile = new File(foldername + fileName);
        OutputStreamWriter osw;

         try{
            if(!targetFile.exists()){
                targetFile.createNewFile();
                osw = new OutputStreamWriter(new FileOutputStream(targetFile),"utf-8");
                osw.write(stringToWrite);  
                osw.close();
            }else{
                osw = new OutputStreamWriter(new FileOutputStream(targetFile,true),"utf-8");
                osw.write("\n"+stringToWrite);
                osw.flush();
                osw.close();
            }
         } catch (Exception e) {
            Toast.makeText(context,e.toString(),Toast.LENGTH_LONG).show();
         }
    }else{
        Toast.makeText(context,"未發現SD卡！",Toast.LENGTH_LONG).show();
    }



  }</pre>