问题
HttpURLConnection con = null;
Response response = new Response();
String TAG = "HttpConHandler";
try{
/*
* IMPORTANT:
* User SHOULD provide URL Encoded Parms
*/
Log.p(TAG, "URL="+ urlStr);
String q=httpHeaders.get("Authorization");
URL url = new URL(urlStr);
con = (HttpURLConnection) url.openConnection();
con.setRequestProperty("Authorization", q);
con.setRequestProperty("GData-Version", "3.0");
Hi I am getting java.lang.IllegalStateException: Cannot set method after connection is made
error when setRequestProperty
method is called ,but when I call this method before connection I get NullPointerException
because con
is null. What can I do to solve this?
回答1:
Please check this URL from Google : http://developer.android.com/reference/java/net/HttpURLConnection.html
It is ok to use the openConnection()
method before setting your headers. Here are the steps from the documentation:
- Obtain a new HttpURLConnection by calling URL.openConnection() and casting the result to HttpURLConnection.
- Prepare the request. The primary property of a request is its URI. Request headers may also include metadata such as credentials, preferred content types, and session cookies.
- Optionally upload a request body. Instances must be configured with
setDoOutput(true)
if they include a request body. Transmit data by writing to the stream returned bygetOutputStream()
. - Read the response. Response headers typically include metadata such as the response body's content type and length, modified dates and session cookies. The response body may be read from the stream returned by
getInputStream()
. If the response has no body, that method returns an empty stream. - Disconnect. Once the response body has been read, the
HttpURLConnection
should be closed by callingdisconnect()
. Disconnecting releases the resources held by a connection so they may be closed or reused.
However if the problem persists you can either try to debug you code and check the connection.connected private flag to see where it becomes true; I've experienced a similar problem after making a call to the getContentType()
method.
Otherwise you can just switch to HttpClient API:
HttpClient httpclient = new DefaultHttpClient();
// Prepare a request object
HttpGet httpget = new HttpGet(url);
// Execute the request
HttpResponse response;
try {
response = httpclient.execute(httpget);
....
回答2:
Don't use URL's convenience method, either use an HttpURLConnection or other library.
回答3:
This may work:
URL url = new URL(urlStr);
con = (HttpURLConnection) url.openConnection();
con.setDoOutput(true);
con.setRequestProperty("Authorization", q);
con.setRequestProperty("GData-Version", "3.0");
来源:https://stackoverflow.com/questions/7726195/setrequestproperty-method-giving-java-lang-illegalstateexception-cannot-set-met