java - ConnectException 在一台机器上，但在另一台机器上没有

Question

我有以下代码片段:

private static String post(String msg) throws Exception {
    URL urlObj = new URL(host);
    HttpURLConnection con = (HttpURLConnection) urlObj.openConnection();

    System.out.println(String.format("Send to url [%s]", urlObj));
    System.out.println(String.format("Port [%s]", con.getURL().getDefaultPort()));
    System.out.println(String.format("POST data [%s]", msg));

    con.setRequestMethod("POST");
    con.setRequestProperty("Content-Type", "text/xml; charset=utf-8");

    con.setDoOutput(true);
    DataOutputStream wr = new DataOutputStream(con.getOutputStream());
    wr.writeBytes(msg);
    wr.flush();
    wr.close();

    int respCode = con.getResponseCode();
    System.out.println(String.format("Response code [%s]", respCode));

    BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
    String response = "", s;
    while ((s = in.readLine()) != null) {
        response += s;
    }
    in.close();

    return response;
}

此方法是程序的一部分，该程序接收 yyyyMMdd 日期字符串，将其包装在 JSON 中，以 Base 64 加密 JSON 字符串，然后将其作为查询发送到 https Web 服务。

我在连接到互联网的个人笔记本电脑上运行该程序，并且能够成功查询和处理结果。我还可以访问 Web 服务 URL 并手动提交查询。

但是，在通过代理连接到 Internet 的服务器上，我仍然可以通过浏览器手动查询 Web 服务，但现在当我运行相同的程序时会出现异常:

java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:579)
    at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:625)
    at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:160)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
    at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264)
    at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:933)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1092)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(HttpsURLConnectionImpl.java:250)
    at com.chinkai.EvaWSAgent.post(EvaWSAgent.java:87)
    at com.chinkai.EvaWSAgent.retrieve(EvaWSAgent.java:50)
    at com.chinkai.EvaWSAgent.main(EvaWSAgent.java:155)

...第 87 行在哪里

DataOutputStream wr = new DataOutputStream(con.getOutputStream());

我不确定如何解决此问题，或者是否有任何方法可以重写此方法来解决，或者这是否是我的问题(也许是代理中的设置？)不确定这是否是提出这个问题的正确位置，但无论如何，我还是想试试运气。

Answer 1

如果服务器通过代理连接到互联网，您还需要在您的应用程序中进行设置，例如像这样:

URL urlObj = new URL(host);

Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("proxy.yourdomain.com", 3128));
HttpURLConnection con = (HttpURLConnection) urlObj.openConnection(proxy);