Java:执行 HTTP REST GET 调用而不读取响应

Question

我所处的场景是向 JVM 服务器发送 HTTP GET。此 HTTP GET 的目的是停止远程 JVM(它将像在 Kubernetes Pod 中一样自动重新启动)。

我观察到，当使用 cURL 发送请求时，它会按预期工作:

$ curl namespace.192.168.42.204.nip.io/rest

但是，当用 Java 发送 HTTP GET 时，它会失败，因为它尝试读取响应，该响应为 null:

private String sendGet(String url) throws Exception {

    URL obj = new URL(url);
    HttpURLConnection con = (HttpURLConnection) obj.openConnection();

    // optional default is GET
    con.setRequestMethod("GET");

    int responseCode = con.getResponseCode();

    System.out.println("Response Code : " + responseCode);

    BufferedReader in = new BufferedReader(
            new InputStreamReader(con.getInputStream()));
    String inputLine;
    StringBuffer response = new StringBuffer();

    while ((inputLine = in.readLine()) != null) {
        response.append(inputLine);
    }

    in.close();

    return "SUCCESS";

}

事实上，当我尝试读取responseCode时，会抛出异常:

java.net.UnknownHostException: namespace.192.168.42.204.nip.io/rest
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at java.net.Socket.connect(Socket.java:538)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:463)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:558)
    at sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
    at sun.net.www.http.HttpClient.New(HttpClient.java:339)
    at sun.net.www.http.HttpClient.New(HttpClient.java:357)
    at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1220)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1156)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1050)
    at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:984)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
    at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)

是否可以在 Java 中模拟 cURL 行为？需要发送 GET 请求而不读取响应。你知道用 Java 实现这一点的方法吗？

Answer 1

如果没有什么可读的，也许你可以调用 connect

con.connect();
con.close();