java - HTTP Get : Only download the header?(不支持HEAD)

Question

在我的代码中，我使用一些 Http Get 请求以流的形式下载一些文件。我使用以下代码:

public String getClassName(String url) throws ClientProtocolException, IOException {
        HttpResponse response = sendGetRequestJsonText(url);

        Header[] all = response.getAllHeaders();
        for (Header h : all) {
            System.out.println(h.getName() + ": " + h.getValue());
        }

        Header[] headers = response.getHeaders("Content-Disposition");
        InputStreamParser.convertStreamToString(response.getEntity().getContent());
        String result = "";
        for (Header header : headers) {
            result = header.getValue();
        }
        return result.substring(result.indexOf("''") + "''".length(), result.length()).trim();
    }

但这会下载响应的全部内容。我只想检索没有内容的 http header 。 HEAD 请求似乎不起作用，因为那时我得到状态 501，未实现。我该怎么做？

Answer 1

您可以考虑只发出 HEAD 而不是发出 GET 请求要求:

The HEAD method is identical to GET except that the server MUST NOT return a message-body in the response. The metainformation contained in the HTTP headers in response to a HEAD request SHOULD be identical to the information sent in response to a GET request. This method can be used for obtaining metainformation about the entity implied by the request without transferring the entity-body itself. This method is often used for testing hypertext links for validity, accessibility, and recent modification.