code: public static String file2String(Class clazz, String relativePath, String encoding) throws IOException {
          InputStream is = null;
          InputStreamReader reader = null;
          BufferedReader bufferedReader = null;
          try {
              is = clazz.getResourceAsStream(relativePath);
              reader = new InputStreamReader(is, encoding);
              bufferedReader = new BufferedReader(reader);
              StringBuilder context = new StringBuilder();
              String lineText;
              while ((lineText = bufferedReader.readLine()) != null) {
                  context.append(lineText).append(LINE_SEPARATOR);
              }
              return context.toString();
          } finally {
              if (bufferedReader != null) {
                  bufferedReader.close();
              }
              if (reader != null) {
                  reader.close();
              }
              if (is != null) {
                  is.close();
              }
          }
      }
docs: 读取类相对路径内容
  
  @param clazz        文件
  @param relativePath 相对路径
  @param encoding     编码
  @return 文件内容
  @throws IOException 发送IO异常