HttpClient(4.3.5) - HTTP Request & HTTP Response

HTTP Request

All HTTP requests have a request line consisting a method name, a request URI and an HTTP protocol version.

HttpClient supports out of the box all HTTP methods defined in the HTTP/1.1 specification:

GET

,

HEAD

,

POST

,

PUT

,

DELETE

,

TRACE

and

OPTIONS

. There is a specific class for each method type.:

HttpGet

,

HttpHead

,

HttpPost

,

HttpPut

,

HttpDelete

,

HttpTrace

, and

HttpOptions

.

The Request-URI is a Uniform Resource Identifier that identifies the resource upon which to apply the request. HTTP request URIs consist of a protocol scheme, host name, optional port, resource path, optional query, and optional fragment.

HttpGet httpget = new HttpGet(
"http://www.google.com/search?hl=en&q=httpclient&btnG=Google+Search&aq=f&oq=");

HttpClient provides

URIBuilder

utility class to simplify creation and modification of request URIs.

URI uri = new URIBuilder()
.setScheme("http")
.setHost("www.google.com")
.setPath("/search")
.setParameter("q", "httpclient")
.setParameter("btnG", "Google Search")
.setParameter("aq", "f")
.setParameter("oq", "")
.build();
HttpGet httpget = new HttpGet(uri);
System.out.println(httpget.getURI());

stdout >

http://www.google.com/search?q=httpclient&btnG=Google+Search&aq=f&oq=

HTTP Response

HTTP response is a message sent by the server back to the client after having received and interpreted a request message. The first line of that message consists of the protocol version followed by a numeric status code and its associated textual phrase.

HttpResponse response = new BasicHttpResponse(HttpVersion.HTTP_1_1,
HttpStatus.SC_OK, "OK");

System.out.println(response.getProtocolVersion());
System.out.println(response.getStatusLine().getStatusCode());
System.out.println(response.getStatusLine().getReasonPhrase());
System.out.println(response.getStatusLine().toString());

stdout >

HTTP/1.1
200
OK
HTTP/1.1 200 OK