从sdcard加载文件

可以结合浏览文件的代码让用户可以选文件

		/**
		 * 判断sd卡是否存在 Environment.getExternalStorageState() 得到sd卡当前的状态
		 * 
		 * getExternalStorageState() returns MEDIA_MOUNTED if the media is
		 * present and mounted at its mount point with read/write access. 如果返回
		 * MEDIA_MOUNTED表示外部存储设备存在。并且有读写的权限(因为sd卡有写保护 如果写保护关闭也是没有权限读写的)
		 */
		String fileNameString = "espeak-data/example.txt";
		int info;
		if (Environment.getExternalStorageState().equals(
				Environment.MEDIA_MOUNTED)) {
			if ("".equals(fileNameString)) {
				info = R.string.sdNotExit;
			} else {
				FileInputStream fileInputStream = null;
				try {
					/**
					 * Environment.getExternalStorageDirectory(); 得到外存储设备的路径
					 * 
					 */
					File file = new File(Environment.getExternalStorageDirectory(), fileNameString);
					fileInputStream = new FileInputStream(file);
					String contentString = DataManager.readDate(fileInputStream);
					mEditText.setText(contentString);
				} catch (Exception e) {
					info = R.string.infor;
				} finally {
					try {
						if (fileInputStream != null) {
							fileInputStream.close();
						}
					} catch (IOException e) {
						info = R.string.infor;
					}
				}
			}
		} else {
			info = R.string.infor;
		}