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，并且需要发送一个没有消息体的 POST 请求。

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

当我尝试以上方法时，我收到了411错误代码。 我还尝试设置“Content-Length”标头为“0”，但发现受到限制。 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();

它抛出了java.io.FileNotFoundException

通常我应该使用以下响应：

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

那我该如何发起这个请求呢？

- Ozan

---

你是否搜索过 java http client post zero length？ - Jim Garrison

是的，但似乎在Java 11 HttpClient中无法实现。有人说JDK 12+可以实现。 - Ozan

Answer 1

如果我启用-Djdk.httpclient.HttpClient.log=requests,headers，在Jdk 11上使用HttpClient应该也能做到同样的事情。我可以看到在下面的请求中发送了Content-Length: 0：

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());

- daniel

---

这个答案的关键部分是 .version(HttpClient.Version.HTTP_1_1) - 这就是解决问题的方法。当使用HTTP 2时，如果Content-Length头为零，HttpClient会省略它。 - Daniel Schilling

Answer 2

我使用HttpURLConnection实现了它：

HttpURLConnection con = (HttpURLConnection) urlBuilder.toURL().openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);
con.setRequestProperty("Authorization", "Bearer " + getCargoApiAuthToken());
con.setFixedLengthStreamingMode(0);
con.connect();

if (con.getResponseCode() != 200 && con.getResponseCode() != 201) {
    // Error response scenario
    return;
}

BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));

StringBuilder stringBuilder = new StringBuilder();

String line;
while ((line = reader.readLine()) != null) {
    stringBuilder.append(line).append("\n");
}

CancelDeliveryResponse cancelDeliveryResponse = gson.fromJson(stringBuilder.toString(), CancelDeliveryResponse.class);

- Ozan