“java.lang.IllegalStateException: Cannot set reque

问题:

I am new to Android and trying to get HTML content of a web page and that is when I came across this issue.

java.lang.IllegalStateException: Cannot set request property after connection is made

Code :

public static String getHTMLPage(String inputURL, String host, String referer, String cookie, String breakString) {

    String htmlContent = "";
    try {
        URL u = new URL(inputURL);
        HttpURLConnection uc = (HttpURLConnection) u.openConnection();
        uc.setRequestProperty("Host", host);
        uc.setRequestProperty("Connection", "keep-alive");
        if (!referer.isEmpty()) {
            uc.setRequestProperty("Referer", referer);
        }
        uc.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/13.0.782.112 Safari/535.1");
        uc.setRequestProperty("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
        uc.setRequestProperty("Accept-Encoding", "html");
        uc.setRequestProperty("Accept-Language", "en-US,en;q=0.8");
        uc.setRequestProperty("Accept-Charset", "ISO-8859-1,utf-8;q=0.7,*;q=0.3");

        if (!cookie.isEmpty()) {
            uc.setRequestProperty("Cookie", cookie);
        }

        BufferedReader br = new BufferedReader(new InputStreamReader(uc.getInputStream()));
        String line = "";
        while ((line = br.readLine()) != null) {
            if (!breakString.isEmpty() && line.contains(breakString)) {
                break;
            }
            htmlContent += line;
        }
        br.close();
    } catch (Exception e) {
        System.out.println(e);
    }
    return htmlContent;
}

Basically, I have written this in a pure java application (where it is working fine) and I just wanted to re-use the same. I have googled and found few SO pages (1,2,3,4), but none of them addresses the problem specific to HTTPURLConnection directly. (Though, some advised about HTTPClient, which is found to be deprecated which I don't want to use.)

Adding getResponseCode() is returning the value as 200 successfully.

System.out.println("RESPONSE CODE : "+uc.getResponseCode());

I have looked the reference page and which states

public void setRequestProperty (String field, String newValue)

Sets the value of the specified request header field. The value will only be used by the current URLConnection instance. This method can only be called before the connection is established.

How I can set the request property before making the connections ? As per the code, we are getting the HTTPURLConnection object only after opening connection for a specific URL (and casting it with HTTPURLConnection)

         HttpURLConnection uc = (HttpURLConnection) u.openConnection();

What is the correct way to use HTTPURLConnection to read HTML page along with setRequestProperty ?

回答1:

The connection isn't created by 'URL.openConnection().` It is created when you get the input or error stream or the response code.

NB you shouldn't call setDoOutput(true) unless you are going to do output, which you aren't here. It sets the HTTP method to POST.