如何将文件内容转成String字符串

try {
    //spring,springBoot环境下可以使用此方式，也可以直接new File(path)
      File keyWordFile = ResourceUtils.getFile("classpath:keyWord.txt");
      BufferedReader reader = new BufferedReader(new FileReader(keyWordFile));
      //使用StringBuilder更快，但不安全，因为此处只有读，所以不影响
      StringBuilder buffer = new StringBuilder();
      String keyWord = null;
      while ((keyWord = reader.readLine()) != null) {
          buffer.append(keyWord);
      }
      //去除字符串中的空格
      String keyWords = buffer.toString().replaceAll("\\s*", "");
  } catch (FileNotFoundException e) {
      e.printStackTrace();
  } catch (IOException e) {
      e.printStackTrace();
 }

    String s = IOUtils.toString(new FileInputStream(keyWordFile) , "UTF-8");
  //去除空格和换行符
    String keyWords = keyWordStr.replaceAll("\\s*", "").replaceAll("\\n","");

 public static String toString(InputStream input, Charset encoding) throws IOException {
        StringBuilderWriter sw = new StringBuilderWriter();
        copy((InputStream)input, (Writer)sw, (Charset)encoding);
        return sw.toString();
  }
  
  public static void copy(InputStream input, Writer output, Charset inputEncoding) throws IOException {
        InputStreamReader in = new InputStreamReader(input, Charsets.toCharset(inputEncoding));
        copy((Reader)in, (Writer)output);
  }

  public static int copy(Reader input, Writer output) throws IOException {
       long count = copyLarge(input, output);
       return count > 2147483647L ? -1 : (int)count;
  }

 public static long copyLarge(Reader input, Writer output) throws IOException {
      return copyLarge(input, output, new char[4096]);
 }

 public static long copyLarge(Reader input, Writer output, char[] buffer) throws IOException {
        long count;
        int n;
        for(count = 0L; -1 != (n = input.read(buffer)); count += (long)n) {
            output.write(buffer, 0, n);
        }
        return count;
    }