Android SD卡内的文件读写操作，androidsd卡内读写,private Stri

Android SD卡内的文件读写操作，androidsd卡内读写,private Stri

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,"未发现SD卡！",Toast.LENGTH_LONG).show();            return "SD Card error";        }    }

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,"未发现SD卡！",Toast.LENGTH_LONG).show();        }      }