怎么获得一url的响应然后建立连接读取字符串资源

 public static String getTextByUrl(String url){
    	StringBuilder stringBuilder = new StringBuilder();
    	URL uri;
		try {
			uri = new URL(url);
			URLConnection conn = uri.openConnection();
			
	        InputStream inStream = conn.getInputStream();	       
	        BufferedReader r = new BufferedReader(new InputStreamReader(inStream), 1000);
	        for (String line = r.readLine(); line != null; line = r.readLine()) {
	        	stringBuilder.append(line);
	        }
	        inStream.close();
	        
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return null;
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return null;
		}
        
        return stringBuilder.toString();
    }

public delegate void HttpHandle(object sender, HttpResultArgs args);
    public class HttpGet
    {
        public event HttpHandle HttpGetCompleted;
        public string url;

        public void GetRequestAsync(string url)
        {
            string resultStrings;
            HttpWebRequest req = HttpWebRequest.CreateHttp(url);
            req.BeginGetResponse((ar) =>
            {
                HttpWebRequest req2 = (HttpWebRequest)ar.AsyncState;
                HttpWebResponse response;

                // End the get response operation 
                response = (HttpWebResponse)req2.EndGetResponse(ar);
                Stream streamResponse = response.GetResponseStream();
                StreamReader streamReader = new StreamReader(streamResponse);
                resultStrings = streamReader.ReadToEnd();
                if (HttpGetCompleted != null)
                {
                    HttpResultArgs args = new HttpResultArgs();
                    args.resultString = resultStrings;
                    HttpGetCompleted(this, args);
                }
            }
            , req);
        }
    }