文件读取权限

       读取sdcard文件  

String state = Environment.getExternalStorageState();
		if(Environment.MEDIA_MOUNTED.equals(state)){
			if(Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)){
				//只能读数据
			}else{
				String path = Environment.getExternalStorageDirectory().getPath();
				String path2 = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getPath();
			}
		}

 读取内存文件

try {
			FileInputStream in = openFileInput("huaxin.txt");
			byte [] buffer = new byte[1024];
			int len;
			StringBuffer sb = new StringBuffer();
			while((len = in.read(buffer)) != -1){
				sb.append(new String(buffer,0,len,"UTF-8"));
			}
			System.out.println(sb.toString());
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

 往内存写文件

try {
			FileOutputStream out = openFileOutput("huaxin.txt", Context.MODE_PRIVATE);
			out.write("I am huaxin".getBytes("UTF-8"));
			out.flush();
			out.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}