Question

我对gae有疑问。我有一个申请http://www.similarityface.appspot.com/query。我正在尝试通过java中的程序与此应用程序通信，以通过POST方法执行查询。产生500错误的问题。代码在下面，有人可以帮我说出我做错了什么。

public class Vetores_Facebook {
   public static void main(String[] args) throws UnsupportedEncodingException, IOException {
        final String server = "https://www.similarityface.appspot.com/query";
        URL url = null;
        try {
            url = new URL(server);

    } catch (MalformedURLException ex) {
        Logger.getLogger(Vetores_Facebook.class.getName()).log(Level.SEVERE, null, ex);
    }

    HttpURLConnection urlConn = null;
    try {
        // URL connection channel.
        urlConn = (HttpURLConnection) url.openConnection();

    } catch (IOException ex) {
        Logger.getLogger(Vetores_Facebook.class.getName()).log(Level.SEVERE, null, ex);
    }


    urlConn.setDoOutput (true);

    // No caching, we want the real thing.
    urlConn.setUseCaches (false);

    try {    

        urlConn.setRequestMethod("POST");
    } catch (ProtocolException ex) {
        Logger.getLogger(Vetores_Facebook.class.getName()).log(Level.SEVERE, null, ex);
    }

    try {

        urlConn.connect();
    } catch (IOException ex) {
        Logger.getLogger(Vetores_Facebook.class.getName()).log(Level.SEVERE, null, ex);
    }

    String message = URLEncoder.encode("get_object(\"me\", metadata=1)", "UTF-8");
    try (OutputStreamWriter writer = new OutputStreamWriter(urlConn.getOutputStream())) {
        writer.write(message);
        writer.close();

    }



     if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
         System.out.println("ok");
        }
     else{
            int x = urlConn.getResponseCode();
            System.out.println("error "+x);

     }
 }
}

Answer 1

try {

    urlConn.connect();
} catch (IOException ex) {
    Logger.getLogger(Vetores_Facebook.class.getName()).log(Level.SEVERE, null, ex);
}

String message = URLEncoder.encode("get_object(\"me\", metadata=1)", "UTF-8");
try (OutputStreamWriter writer = new OutputStreamWriter(urlConn.getOutputStream())) {
    writer.write(message);
    writer.close();

}

问题是你在调用urlConn.connect（）;这似乎刷新了你可能拥有的任何输出缓冲区，并准备连接以获取输入流。在此之后尝试写入以打开输出流将导致异常。

使用此处给出的示例以正确的方式执行此操作：https://developers.google.com/appengine/docs/java/urlfetch/usingjavanet#Using_HttpURLConnection

使用Google AppEngine和类java.net时出错500

1 个答案: