Suppose u have the whole URL as: < https://cs14.salesforce.com/apex/myVFpage?id=906F00000008w9wIAA >

    String baseURL = URL.getSalesforceBaseUrl().toExternalForm(); 

// it will return: < https://cs14.salesforce.com >

    String PageURL = ApexPages.currentPage().getUrl();  

 // it will return: < /apex/myVFpage?id=906F00000008w9wIAA >

So to get your whole exact URL you can write:

    String wholeURL = baseURL+PageURL; 

// it will return: < https://cs14.salesforce.com/apex/myVFpage?id=906F00000008w9wIAA >