Android SD卡内的文件读写操作详解编程语言

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(); 
        } 
          
           
          
      }