public class linkedinauth {
    public String x{get;set;}
    public static final string REDIRECT_URL='https://test.salesforce.com/services/authcallback/*****000000Ua7EAE/LinkedIn';
    public static final string LINKEDIN_API_KEY='******ahx9s8jg';
    public static final string OAUTH_CODE_END_POINT_URL='https://www.linkedin.com/uas/oauth2/authorization?response_type=code';
    public static final string SCOPE='r_basicprofile';
    public static final string STATE='75etfdcdgsdvvsdgd';

   public PageReference connect(){
     x=OAUTH_CODE_END_POINT_URL+'&client_id='+LINKEDIN_API_KEY+'&scope='+SCOPE+'&state='+EncodingUtil.urlEncode(STATE,'UTF-8')+'&redirect_uri='+EncodingUtil.urlEncode(REDIRECT_URL,'UTF-8');
     PageReference pageRef = new PageReference(x);
     return pageRef;
   }
}