Host name may not be null in HttpResponse execute for android

问题

I get the error "Target host must not be null, or set in parameters".

I DO have Internet permission in my manifest file
I have put 'http://' before my Url
I DO encode the URL

This is my code:

   String url = "http://maps.google.com/maps/api/directions/json?origin=1600 Pennsylvania Avenue NW, Washington, DC 20500&destination=1029 Vermont Ave NW, Washington, DC 20005&sensor=false";
   HttpClient httpclient = new DefaultHttpClient();
   String goodURL = convertURL(url);//change weird characters for %etc
   HttpPost httppost = new HttpPost(goodURL);
   HttpResponse response = httpclient.execute(httppost);

In 5th line (last line above), my program throws an exception. here is the exact error:

java.lang.IllegalArgumentException: Host name may not be null

I Do encode my string in method convertURL...

goodURL= http://maps.google.com/maps/api/directions/json?origin=3%20Cedar%20Ave%2c%20Highland%20Park%2c%20NJ%2008904&destination=604%20Bartholomew%20Road%2c%20Piscataway%2c%20New%20Jersey%2008854&sensor=false

Any suggestions? Thanks!

回答1:

I'm not sure what your URL encode method is doing, but if you are using a method from the framework like URLEncoder, you should never pass the full URL, just the parameters list you need to encode to escape special characters.

Encoding the full URL will percent escape every character, including the :// into %3A%2F%2F and all additional slashes into %2F.

Take a look at the value of your goodUrl string after you encode it.

回答2:

Just use:

URLEncoder.encode(YOUR_STRING);

回答3:

Encode your URL string before you post the request, but only encode the parameters after the ?:

String url = "http://maps.google.com/maps/api/directions/json?";
String params = "origin=1600 Pennsylvania Avenue NW, Washington, DC 20500&destination=1029 Vermont Ave NW, Washington, DC 20005&sensor=false";
HttpClient httpclient = new DefaultHttpClient();
String goodParams = convertURL(params);//change weird characters for %etc
HttpPost httppost = new HttpPost(url + goodParams);
HttpResponse response = httpclient.execute(httppost);

来源：https://stackoverflow.com/questions/12537522/host-name-may-not-be-null-in-httpresponse-execute-for-android

标签

android

http-post

httpresponse

illegalargumentexception