android中如何读取txt文件的内容以及其编码问题

public static String (String strFilePath)
{
    String path = strFilePath;
    String content = ""; //文件内容字符串
    //打开文件
    File file = new File(path);
    //如果path是传递过来的参数，可以做一个非目录的判断
    if (file.isDirectory())
    {
        Log.d("TestFile", "The File doesn't not exist.");
    }
    else
    {
        try {
            InputStream instream = new FileInputStream(file);
            InputStreamReader inputStreamReader = null;
            try {
                inputStreamReader = new InputStreamReader(instream, "utf-8");
            } catch (UnsupportedEncodingException e1) {
                e1.printStackTrace();
            }
            BufferedReader reader = new BufferedReader(inputStreamReader);
            StringBuffer sb = new StringBuffer("");
            String line;
            try {
                while ((line = reader.readLine()) != null) {
                    sb.append(line);
                    sb.append("n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            content = sb.toString();
        }
        catch (java.io.FileNotFoundException e)
        {
            Log.d("TestFile", "The File doesn't not exist.");
        }
        catch (IOException e)
        {
            Log.d("TestFile", e.getMessage());
        }
    }
    return content;
}