Java 11 发送不带正文的 HTTP POST 请求

Question

我正在使用 java 11 http 客户端，我需要发送一个没有正文的 post 请求。

HttpRequest request = getRequestBuilder()
    .uri(urlBuilder.toURL().toURI())
    .POST(HttpRequest.BodyPublishers.noBody())
    .build();
HttpResponse<String> httpResponse = httpClient.send(request, HttpResponse.BodyHandlers.ofString()); 

当我按照上面的方法尝试时，我收到 411 错误代码。我还尝试将“Content-Length”标头设置为“0”，但发现这是受到限制的。

然后我尝试了这个：

    URL url = new URL(getHost());
    Map<String,Object> params = new LinkedHashMap<>();
    params.put("trackingNo", orderPackage.getCargoTrackingCode());
    params.put("referenceNo", orderPackage.getCargoCode());

    StringBuilder postData = new StringBuilder();
    for (Map.Entry<String,Object> param : params.entrySet()) {
        if (postData.length() != 0) postData.append('&');
        postData.append(URLEncoder.encode(param.getKey(), "UTF-8"));
        postData.append('=');
        postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
    }
    byte[] postDataBytes = postData.toString().getBytes("UTF-8");

    HttpURLConnection conn = (HttpURLConnection)url.openConnection();
    conn.setRequestMethod("POST");
    conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
    conn.setDoOutput(true);
    conn.getOutputStream().write(postDataBytes);

    Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));

    StringBuilder sb = new StringBuilder();
    for (int c; (c = in.read()) >= 0;)
        sb.append((char)c);
    String response = sb.toString();

它抛出java.io.FileNotFoundException

通常我应该使用如下响应：

CancelDeliveryResponse cancelDeliveryResponse = gson.fromJson(httpResponse.body(), CancelDeliveryResponse.class);

那么我该如何提出这个请求呢？

Answer 1

您应该能够对 HttpClient 执行相同的操作 - 在 Jdk 11 上，如果我启用日志记录，-Djdk.httpclient.HttpClient.log=requests,headers我可以看到 Content-Length: 0 是通过以下请求发送的：

HttpRequest request = HttpRequest.newBuilder()
    .uri(<uri>)
    .header("Authorization", "Bearer " + <token>)
    .version(HttpClient.Version.HTTP_1_1)
    .POST(HttpRequest.BodyPublishers.noBody())
    .build();
HttpResponse<String> httpResponse = httpClient.send(request, HttpResponse.BodyHandlers.ofString());