httpurlconnection非法状态异常:已连接

Question

我试图发布参数并从输入流读取重定向的页面,但我不知道任何此异常

Exception in thread "main" java.lang.IllegalStateException: Already connected
    at java.net.URLConnection.setDoOutput(URLConnection.java:900)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.setDoOutput(HttpsURLConnectionImpl.java:455)
    at com.company.Main.main(Main.java:58)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

码:

try {

        CookieHandler cookieHandler = null;
        CookieManager.setDefault(cookieHandler);


        HttpURLConnection urlConnection = (HttpURLConnection) new URL("site").openConnection();
        InputStream i = new BufferedInputStream(urlConnection.getInputStream());
        StringBuilder stringBuilder =new StringBuilder();


        int c;
        while ((c=i.read())!=-1){
            stringBuilder.append((char)c);
        }

         // for getting the post paramters that is user name and password field
        Pattern p = Pattern.compile("<input name=\"\\w{22}\" type=\"text\" id=\"\\w{22}\" />");
        Matcher matcher = p.matcher(stringBuilder.toString());

        String user_name = null;
        while (matcher.find()){

            user_name = matcher.group().split("\"")[1];

        }

        String password = null;
        p= Pattern.compile("<input name=\"\\w{22}\" type=\"password\" id=\"\\w{22}\" />");
        matcher= p.matcher(stringBuilder.toString());
        while (matcher.find()){

            password = matcher.group().split("\"")[1];

        }
        System.out.print(user_name + "  "  + password);



        String urlParameters  = user_name+"=xyz&"+password+"=xyz";
        byte[] postData       = urlParameters.getBytes( StandardCharsets.UTF_8 );
        int    postDataLength = postData.length;

        urlConnection.setDoOutput(true);
        urlConnection.setDoInput(true);
        urlConnection.setRequestMethod("POST");
        urlConnection.setRequestMethod(Integer.toString(postDataLength));


        Writer writer = new BufferedWriter(new OutputStreamWriter(urlConnection.getOutputStream()));
        writer.write(urlParameters);
        writer.flush();

        urlConnection.setDoInput(true);
        urlConnection.getContent();

        while ((c=i.read())!=-1){
            System.out.print((char)c);

        }


    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 1

你需要调用urlConnection.setDoInput(true),urlConnection.setDoOutput(true),urlConnection.setRequestMethod("POST"),urlConnection.setRequestMethod(Integer.toString(postDataLength))和之前调用更改查询任何其他方法urlConnection.getInputStream(),并urlConnection.getOutputStream()为这些方法实际上将启动请求,以便调用一次实在来不及修改,这就是为什么你这样做的原因请求Exception.

响应更新

您实际面临的主要问题是由于您希望重用HttpURLConnection它而不打算重用,这就是您遇到此异常的原因,您需要HttpURLConnection为每个HTTP请求创建一个新的.