HttpClient Quick Start

1. Download 'Binary' package of the latest official release from the project download page.

   There should be 7 jars in total (components marked with (*) include additional features and are optional) on the classpath.

   • commons-logging-x.x.x.jar
   • commons-codec-x.x.x.jar
   • httpcore-x.x.x.jar
   • httpclient-x.x.x.jar
   • httpmime-x.x.x.jar (*)
   • httpclient-cache-x.x.x.jar (*)
   • fluent-hc-x.x.x.jar (*)
2. The below code fragment illustrates the execution of HTTP GET and POST requests using the HttpClient native API.

   CloseableHttpClient httpclient = HttpClients.createDefault();
   HttpGet httpGet = new HttpGet("http://targethost/homepage");
   CloseableHttpResponse response1 = httpclient.execute(httpGet);
   // The underlying HTTP connection is still held by the response object
   // to allow the response content to be streamed directly from the network socket.
   // In order to ensure correct deallocation of system resources
   // the user MUST either fully consume the response content  or abort request
   // execution by calling CloseableHttpResponse#close().
   
   try {
       System.out.println(response1.getStatusLine());
       HttpEntity entity1 = response1.getEntity();
       // do something useful with the response body
       // and ensure it is fully consumed
       EntityUtils.consume(entity1);
   } finally {
       response1.close();
   }
   
   HttpPost httpPost = new HttpPost("http://targethost/login");
   List <NameValuePair> nvps = new ArrayList <NameValuePair>();
   nvps.add(new BasicNameValuePair("username", "vip"));
   nvps.add(new BasicNameValuePair("password", "secret"));
   httpPost.setEntity(new UrlEncodedFormEntity(nvps));
   CloseableHttpResponse response2 = httpclient.execute(httpPost);
   
   try {
       System.out.println(response2.getStatusLine());
       HttpEntity entity2 = response2.getEntity();
       // do something useful with the response body
       // and ensure it is fully consumed
       EntityUtils.consume(entity2);
   } finally {
       response2.close();
   }

   Source can be downloaded here

3. The same requests can be executed using a simpler, albeit less flexible, fluent API.

   // The fluent API relieves the user from having to deal with manual deallocation of system
   // resources at the cost of having to buffer response content in memory in some cases.
   
   Request.Get("http://targethost/homepage")
       .execute().returnContent();
   Request.Post("http://targethost/login")
       .bodyForm(Form.form().add("username",  "vip").add("password",  "secret").build())
       .execute().returnContent();
   

   Source can be downloaded here

4. HttpClient Examples - a set of examples demonstrating some of the more complex behavior.
5. HttpClient Tutorial - gives a detailed examination of the HttpClient API, which was written in close accordance with the (sometimes not very intuitive) HTTP specification/standard. A copy is also shipped with the release. A PDF version is also available
6. HttpClient Primer - explains the scope of HttpClient. Note that HttpClient is not a browser. It lacks the UI, HTML renderer and a JavaScript engine that a browser will possess.