You need to send query parameters in a URL.

Set the query string using the setQueryString( ) method on an instance of HttpMethod. Use URIUtil to encode any text included in a URL. The following example puts two parameters on the query string:

               import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.util.URIUtil;

HttpClient client = new HttpClient( );

String url = "http://www.discursive.com/cgi-bin/jccook/param_list.cgi";

HttpMethod method = new GetMethod( url );

// Set the Query String with setQueryString( )
method.setQueryString(URIUtil.encodeQuery("test1=O Reilly&blah=Whoop"));
System.out.println( "With Query String: " + method.getURI( ) );

client.executeMethod( method );

System.out.println( "Response:
 " + method.getResponseBodyAsString( ) );
method.releaseConnection( );

The param_list.cgi CGI script echoes all parameters received, and from the following output, you can see how URIUtil encodes the first parameter:

With Query String: http://www.discursive.com/cgi-bin/jccook/param_list.
cgi?test1=O%20Reilly&blah=Whoop
Response:
 These are the parameters I received:

test1:
  O Reilly
blah:
  Whoop

In the previous example, method.setQueryString() is used to set the entire query string at once, but there is another alternative: setting the query string with an array of NameValuePair objects. When a NameValuePair[] is passed to method.setQueryString( ), the HttpMethod then takes each pair and creates a series of parameters delimited by an ampersand. The approach encourages cleaner code because you are not concatenating strings to pass multiple parameters. The following example sets the same parameters used in the previous example, using NameValuePair objects:

// Set query string with name value pair objects
HttpMethod method = new GetMethod( url );
NameValuePair pair = 
    new NameValuePair( "test1", URIUtil.encodeQuery( "O Reilly" ) );
NameValuePair pair2 = 
    new NameValuePair( "blah", URIUtil.encodeQuery( "Whoop" ) );
NameValuePair[] pairs = new NameValuePair[] { pair, pair2 };
method.setQueryString( pairs );
System.out.println( "With NameValuePairs: " + method.getURI( ) );
client.executeMethod( method );
System.out.println( "Response:
 " + method.getResponseBodyAsString( ) );
method.releaseConnection( );

According to RFC 1738 (Uniform Resource Locators (URL) specification) URLs can only contain alphanumeric characters, [0-9a-zA-Z], and a few other special characters. If you need to send a parameter with an unacceptable character in a URL, you will need to encode your string according to the standard defined in RFC 1738. URIUtil exposes a method encodeQuery( ) that can be used to encode the value “O Reilly” in the previous example. The following code demonstrates the use of URIUtil to encode strings for inclusion in a URL:

String encoded1 = URIUtil.encodeQuery( "<test>=O'Connell" );
String encoded2 = URIUtil.encodeQuery( "one:two=thr ee#" );

String decoded = URIUtil.decode( "Hello%20World%3F" );

System.out.println( "Encoded: " + encoded1 );
System.out.println( "Encoded: " + encoded2 );
System.out.println( "Decoded: " + decoded );

This simple example encodes two strings and decodes an encoded string using URIUtil. The output shows the result of each transformation:

Encoded: %3ctest%e3=O'Connell
Encoded: one%3atwo=thr%20ee#23
Decoded: Hello World?

In this example, URLUtil was used to encode content passed in on the query string. This HttpClient team has recently moved some of the URL encoding and decoding logic to the Jakarta Commons Codec project as a class named URLCodec. For more information about URLCodec, see the Jakarta Commons Codec project page (http://jakarta.apache.org/codec).

RFC 1738 discusses the legal characters for a URL and defines a process for encoding other characters. RFC 1738 can be found at http://www.zvon.org/tmRFC/RFC2616/Output/index.html.