Calling WebServices through HttpClient: A RestClient class for calling webservice using both, get and post methods, and getting the response dropped into an String.

RestClient.java

public class RestClient {
 
    private ArrayList<NameValuePair> params;
    private ArrayList<NameValuePair> headers;
 
    private String url;
 
    private int responseCode;
    private String message;
 
    private String response;
 
    public String getResponse() {
        return response;
    }
 
    public String getErrorMessage() {
        return message;
    }
 
    public int getResponseCode() {
        return responseCode;
    }
 
    public RestClient(String url)
    {
        this.url = url;
        params = new ArrayList<NameValuePair>();
        headers = new ArrayList<NameValuePair>();
    }
 
    public void AddParam(String name, String value)
    {
        params.add(new BasicNameValuePair(name, value));
    }
 
    public void AddHeader(String name, String value)
    {
        headers.add(new BasicNameValuePair(name, value));
    }
 
    public void Execute(RequestMethod method) throws Exception
    {
        switch(method) {
            case GET:
            {
                //add parameters
                String combinedParams = "";
                if(!params.isEmpty()){
                    combinedParams += "?";
                    for(NameValuePair p : params)
                    {
                        String paramString = p.getName() + "=" + URLEncoder.encode(p.getValue(),”UTF-8″);
                        if(combinedParams.length() > 1)
                        {
                            combinedParams  +=  "&" + paramString;
                        }
                        else
                        {
                            combinedParams += paramString;
                        }
                    }
                }
 
                HttpGet request = new HttpGet(url + combinedParams);
 
                //add headers
                for(NameValuePair h : headers)
                {
                    request.addHeader(h.getName(), h.getValue());
                }
 
                executeRequest(request, url);
                break;
            }
            case POST:
            {
                HttpPost request = new HttpPost(url);
 
                //add headers
                for(NameValuePair h : headers)
                {
                    request.addHeader(h.getName(), h.getValue());
                }
 
                if(!params.isEmpty()){
                    request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
                }
 
                executeRequest(request, url);
                break;
            }
        }
    }
 
    private void executeRequest(HttpUriRequest request, String url)
    {
        HttpClient client = new DefaultHttpClient();
 
        HttpResponse httpResponse;
 
        try {
            httpResponse = client.execute(request);
            responseCode = httpResponse.getStatusLine().getStatusCode();
            message = httpResponse.getStatusLine().getReasonPhrase();
 
            HttpEntity entity = httpResponse.getEntity();
 
            if (entity != null) {
 
                InputStream instream = entity.getContent();
                response = convertStreamToString(instream);
 
                // Closing the input stream will trigger connection release
                instream.close();
            }
 
        } catch (ClientProtocolException e)  {
            client.getConnectionManager().shutdown();
            e.printStackTrace();
        } catch (IOException e) {
            client.getConnectionManager().shutdown();
            e.printStackTrace();
        }
    }
 
    private static String convertStreamToString(InputStream is) {
 
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();
 
        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
}

RestClientTester.java

/*
Here is an example of how I use the class to call the Google Analytics API. I use the AddParam methods to add query string
post values and the AddHeader method to add headers to the request. RequestMethod is a simple enum with GET and POST values.
*/

RestClient client = new RestClient(LOGIN_URL);
client.AddParam("accountType", "GOOGLE");
client.AddParam("source", "tboda-widgalytics-0.1");
client.AddParam("Email", _username);
client.AddParam("Passwd", _password);
client.AddParam("service", "analytics");
client.AddHeader("GData-Version", "2");
 
try {
    client.Execute(RequestMethod.POST);
} catch (Exception e) {
    e.printStackTrace();
}
 
String response = client.getResponse();