将文件读取为字符串

我需要在 android 中将 xml 文件作为 String 加载，以便我可以将其加载到 TBXML xml 解析器库并解析它。我现在将文件读取为 String 的实现需要大约 2 秒，即使对于一些 KB 的非常小的 xml 文件也是如此。是否有任何已知的快速方法可以在 Java/Android 中将文件读取为字符串？

这是我现在的代码：

public static String readFileAsString(String filePath) {
    String result = "";
    File file = new File(filePath);
    if ( file.exists() ) {
        //byte[] buffer = new byte[(int) new File(filePath).length()];
        FileInputStream fis = null;
        try {
            //f = new BufferedInputStream(new FileInputStream(filePath));
            //f.read(buffer);

            fis = new FileInputStream(file);
            char current;
            while (fis.available() > 0) {
                current = (char) fis.read();
                result = result + String.valueOf(current);
            }
        } catch (Exception e) {
            Log.d("TourGuide", e.toString());
        } finally {
            if (fis != null)
                try {
                    fis.close();
                } catch (IOException ignored) {
            }
        }
        //result = new String(buffer);
    }
    return result;
}

最终使用的代码如下：

http://www.java2s.com/Code/Java/File-Input-Output/ConvertInputStreamtoString.htm

public static String convertStreamToString(InputStream is) throws Exception {
    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();
    String line = null;
    while ((line = reader.readLine()) != null) {
      sb.append(line).append("\n");
    }
    reader.close();
    return sb.toString();
}

public static String getStringFromFile (String filePath) throws Exception {
    File fl = new File(filePath);
    FileInputStream fin = new FileInputStream(fl);
    String ret = convertStreamToString(fin);
    //Make sure you close all streams.
    fin.close();        
    return ret;
}