android将对象写入文件和从文件中读取对象数据

FileOutputStream fileOutputStream = null;
ObjectOutputStream objectOutputStream = null;
try{
   JSONObject jsonObject=new JSONObject(msg);
   String status=jsonObject.getString("status");
   if(status.equals("1")){
      Gson gson=new Gson();
      teacherResponseList=gson.fromJson(jsonObject.getJSONArray("result").toString(),new TypeToken<List<TeacherResponse>>(){}.getType());
      Log.d("queryteacherandgroup",msg);
      Log.d("query", "查询理财师列表ONACTIVITYCreatedOEHttpCallBack");

      File teacherFile = new File(Environment.getExternalStorageDirectory().toString() + File.separator + "teacher.dat");
      if (!teacherFile.getParentFile().exists()) {
         teacherFile.getParentFile().mkdirs();
      }
      if (!teacherFile.exists()) {
         teacherFile.createNewFile();
      }
      fileOutputStream = new FileOutputStream(teacherFile.toString());
      objectOutputStream = new ObjectOutputStream(fileOutputStream);
      objectOutputStream.writeObject(teacherResponseList);

   }
}catch (Exception e){
   e.getStackTrace();
}finally {
   if (fileOutputStream != null) {
      try {
         fileOutputStream.close();

      } catch (Exception e) {
         e.getStackTrace();
      }
      if (objectOutputStream != null) {
         try {
            objectOutputStream.close();

         } catch (Exception e) {
            e.getStackTrace();
         }
      }
   }
   //mGroupAdapter.notifyDataSetChanged();   
}



 FileInputStream fileInputStream = null;
    ObjectInputStream objectInputStream = null;
    try{
        File teacherFile = new File(Environment.getExternalStorageDirectory().toString() + File.separator + "teacher.dat");
        if (!teacherFile.getParentFile().exists()) {
            teacherFile.getParentFile().mkdirs();
        }
        if (!teacherFile.exists()) {
            teacherFile.createNewFile();
        }
        fileInputStream = new FileInputStream(teacherFile.toString());
        objectInputStream = new ObjectInputStream(fileInputStream);
        teacherResponseList=(List<TeacherResponse> )objectInputStream.readObject();
    }catch (Exception e){
        e.getStackTrace();
    }finally {
        if (fileInputStream != null) {
            try {
                fileInputStream.close();

            } catch (Exception e) {
                e.getStackTrace();
            }
            if (objectInputStream != null) {
                try {
                    objectInputStream.close();

                } catch (Exception e) {
                    e.getStackTrace();
                }
            }
        }
    }


}