How To Use HttpClient

This java based tutorial is designed to provide a basic overview of how to use HttpClient.

Downloaded HttpClient and dependencies listed below that are required to put them on your classpath.

• httpclient-4.2.3.jar from http://hc.apache.org/downloads.cgi/li>
• commons-codec.jar from http://commons.apache.org/codec/
• commons-logging.jar from http://commons.apache.org/logging/
• junit.jar from http://www.junit.org/

The general process for using HttpClient consists of a number of steps:

• Create an instance of HttpClient.
• Create an instance of one of the methods (GetMethod in this case). The URL to connect to is passed in to the the method constructor.
• Tell HttpClient to execute the method.
• Read the response.
• Release the connection.
• Deal with the response.

package com.jkoder.http;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClientBuilder;
 
public class HttpClientExample {
 
	public static void main(String[] args) throws Exception {
 
		HttpClient client = new HttpClient();
		GetMethod method = new GetMethod("jkoder.com");
		
		// Provide custom retry handler is necessary
		method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(3, false));

		try {
			// Execute the method.
			int statusCode = client.executeMethod(method);
			//If status code is not 200.
			if (statusCode != HttpStatus.SC_OK) {
				System.err.println("Method failed: " + method.getStatusLine());
			}

			// Read the response body.
			byte[] responseBody = method.getResponseBody();
			System.out.println(new String(responseBody));

		} catch (HttpException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			method.releaseConnection();
		}
	}
}