docs: private HttpResponse init() throws HttpException {
  		try {
  			this.status = httpConnection.responseCode();
  			this.in = (this.status < HttpStatus.HTTP_BAD_REQUEST) ? httpConnection.getInputStream() : httpConnection.getErrorStream();
  		} catch (IOException e) {
  			if (e instanceof FileNotFoundException) {
  				// 服务器无返回内容，忽略之
  			} else {
  				throw new HttpException(e);
  			}
  		}
  
  		try {
  			this.headers = httpConnection.headers();
  		} catch (IllegalArgumentException e) {
  			StaticLog.warn(e, e.getMessage());
  		}
  		final Charset charset = httpConnection.getCharset();
  		this.charsetFromResponse = charset;
  		if (null != charset) {
  			this.charset = charset;
  		}
  
  		if (null == this.in) {
  			// 在一些情况下，返回的流为null，此时提供状态码说明
  			this.in = new ByteArrayInputStream(StrUtil.format("Error request, response status: {}", this.status).getBytes());
  		} else if (isGzip() && false == (in instanceof GZIPInputStream)) {
  			try {
  				in = new GZIPInputStream(in);
  			} catch (IOException e) {
  				// 在类似于Head等方法中无body返回，此时GZIPInputStream构造会出现错误，在此忽略此错误读取普通数据
  				// ignore
  			}
  		} else if (isDeflate() && false == (in instanceof DeflaterInputStream)) {
  			//Accept-Encoding: defalte
  			in = new DeflaterInputStream(in);
  		}
  
  		// 同步情况下强制同步
  		return this.isAsync ? this : forceSync();
  	}