Apache HTTP Client Example

Apache HTTP Client Example

It has been quite a while since I last posted on HttpURLConnection class to perform GET and POST request operations from a Java client. If you need a refresher on the common components of the URL is strongly recommended to take a few minutes and visit our other earlier post. In this tutorial, we will learn how to perform similar operations using the Apache HttpClient.

Getting Started

In order to run this tutorial yourself, you will need the following:

Required Libraries

Copy all of the following jars to lib folder ofthe current project then use Java Build Path->Add Jars.

httpclient_jars
commons-cli-1.3.1.jar
commons-codec-1.9.jar
commons-logging-1.2.jar
fluent-hc-4.5.jar
httpclient-4.5.jar
httpclient-cache-4.5.jar
httpclient-win-4.5.jar
httpcore-4.4.1.jar
httpmime-4.5.jar
jna-4.1.0.jar
jna-platform-4.1.0.jar
log4j-1.2.17.jar

Complete Project Overview

I have added the project overview to give you a full view of the structure and show you all files contained in this sample project.

httpclient_proj_struct

Using Apache HttpClient

Now that we have added all of the dependency jar files for our project we can begin using our Apache Http Client application. For the sake of simplicity, I have decided to create one main class called ApacheConnection Class which contains methods executeGet, executePost, executeSSLGet, executeSSLPost and executeSSLGetAllTrusting.

All of the methods perform the same basic operations:

  1. Create an instance of HttpClient using HttpClientBuilder
  2. Create an instance of either HttpGet or HttpPost depending on your desired HTTP request type
  3. Next we use addHeader if header parameters are available
  4. For our executePost method, we create a List of NameValuePair and pass any post parameters here.
  5. We then set up our ResponseHandler to handle data from our HTTP request

The ApacheConnection Class (ApacheConnection.java)

package com.avaldes.util;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.List;
import java.util.Map;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.ssl.SSLContextBuilder;
import org.apache.http.ssl.TrustStrategy;
import org.apache.http.util.EntityUtils;
import org.apache.log4j.Logger;

public class ApacheConnection {
  private static final Logger logger = Logger
      .getLogger(ApacheConnection.class);

  public String executePost(String URLAddress,
      Map<String, String> headerParams,
      List<NameValuePair> postParams) throws MalformedURLException {

    HttpClient client = HttpClientBuilder.create().build();
    HttpPost httpPost = new HttpPost(URLAddress);

    if (headerParams != null) {
      for (String header : headerParams.keySet()) {
        httpPost.addHeader(header, headerParams.get(header));
      }
    }

    // Set UTF-8 character encoding to ensure proper 
    // encoding structure in your posts
    if (postParams != null)
      try {
        httpPost
            .setEntity(new UrlEncodedFormEntity(postParams, "UTF-8"));
      } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
      }

    // Set up the response handler
    ResponseHandler<String> handler = new ResponseHandler<String>() {

      @Override
      public String handleResponse(final HttpResponse response)
          throws ClientProtocolException, IOException {

        int status = response.getStatusLine().getStatusCode();

        logger.info("Status: " + status);
        HttpEntity entity = response.getEntity();
        return entity != null ? EntityUtils.toString(entity) : null;
      }
    };
    String responseBody = null;
    try {
      responseBody = client.execute(httpPost, handler);
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return responseBody;
  }

  public String executeGet(String URLAddress,
      Map<String, String> headerParams) throws MalformedURLException {

    HttpClient client = HttpClientBuilder.create().build();
    HttpGet httpGet = new HttpGet(URLAddress);

    if (headerParams != null) {
      for (String header : headerParams.keySet()) {
        httpGet.addHeader(header, headerParams.get(header));
      }
    }

    // Set up the response handler
    ResponseHandler<String> handler = new ResponseHandler<String>() {

      @Override
      public String handleResponse(final HttpResponse response)
          throws ClientProtocolException, IOException {

        int status = response.getStatusLine().getStatusCode();

        logger.info("Status: " + status);
        HttpEntity entity = response.getEntity();
        return entity != null ? EntityUtils.toString(entity) : null;
      }
    };
    String responseBody = null;
    try {
      responseBody = client.execute(httpGet, handler);
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return responseBody;
  }

  public String executeSSLPost(String URLAddress,
      Map<String, String> headerParams,
      List<NameValuePair> postParams) throws MalformedURLException,
      IOException, NoSuchAlgorithmException, KeyManagementException,
      KeyStoreException {

    HttpClientBuilder builder = HttpClientBuilder.create();

    SSLContext sslContext = new SSLContextBuilder()
        .loadTrustMaterial(null, new TrustStrategy() {
          public boolean isTrusted(X509Certificate[] arg0,
              String arg1) throws CertificateException {
            return true;
          }
        }).build();

    @SuppressWarnings("deprecation")
    HostnameVerifier hostnameVerifier = 
				SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER;

    SSLConnectionSocketFactory sslSocketFactory = 
      new SSLConnectionSocketFactory(sslContext, hostnameVerifier);
    Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder
      .<ConnectionSocketFactory> create()
      .register("http",
          PlainConnectionSocketFactory.getSocketFactory())
      .register("https", sslSocketFactory).build();

    PoolingHttpClientConnectionManager connectionMgr = 
			new PoolingHttpClientConnectionManager(socketFactoryRegistry);
    builder.setConnectionManager(connectionMgr);

    builder.setSslcontext(sslContext);

    HttpClient client = builder.build();
    HttpPost httpPost = new HttpPost(URLAddress);

    if (headerParams != null) {
      for (String header : headerParams.keySet()) {
        httpPost.addHeader(header, headerParams.get(header));
      }
    }

    // Set UTF-8 character encoding to ensure proper 
    // encoding structure in your posts
    if (postParams != null)
      httpPost
          .setEntity(new UrlEncodedFormEntity(postParams, "UTF-8"));

    // Set up the response handler
    ResponseHandler<String> handler = new ResponseHandler<String>() {

      @Override
      public String handleResponse(final HttpResponse response)
          throws ClientProtocolException, IOException {

        int status = response.getStatusLine().getStatusCode();

        logger.info("Status: " + status);
        if (status >= 200 && status < 300) {
          HttpEntity entity = response.getEntity();
          return entity != null ? EntityUtils.toString(entity) : null;
        } else {
          throw new ClientProtocolException(
              "Unexpected response status: " + status);
        }
      }
    };
    String responseBody = client.execute(httpPost, handler);
    return responseBody;
  }

  public String executeSSLGet(String URLAddress,
      Map<String, String> headerParams) throws MalformedURLException,
      IOException, KeyManagementException, NoSuchAlgorithmException,
      KeyStoreException {
    HttpClient client = HttpClients.createDefault();
    HttpGet httpget = new HttpGet(URLAddress);

    if (headerParams != null) {
      for (String header : headerParams.keySet()) {
        httpget.addHeader(header, headerParams.get(header));
      }
    }

    logger.info("Executing request " + httpget.getRequestLine());

    // Set up the response handler
    ResponseHandler<String> handler = new ResponseHandler<String>() {

      @Override
      public String handleResponse(final HttpResponse response)
          throws ClientProtocolException, IOException {

        int status = response.getStatusLine().getStatusCode();

        logger.info("Status: " + status);
        if (status >= 200 && status < 300) {
          HttpEntity entity = response.getEntity();
          return entity != null ? EntityUtils.toString(entity) : null;
        } else {
          throw new ClientProtocolException(
              "Unexpected response status: " + status);
        }
      }
    };
    String responseBody = client.execute(httpget, handler);
    return responseBody;
  }

  public String executeSSLGetAllTrusting(String URLAddress)
      throws MalformedURLException, IOException,
      KeyManagementException, NoSuchAlgorithmException,
      KeyStoreException {
    TrustManager[] allTrustingCerts = new TrustManager[] {
        new X509TrustManager() {
          @Override
          public java.security.cert.X509Certificate[] getAcceptedIssuers() {
            logger.info("Inside TrustManager getAcceptedIssuers...");
            return null;
          }

          @Override
          public void checkClientTrusted(X509Certificate[] certs,
              String authType) throws CertificateException {
            logger.info("Inside TrustManager checkClientTrusted...");
          }

          @Override
          public void checkServerTrusted(X509Certificate[] certs,
              String authType) {
            logger.info("Inside TrustManager checkServerTrusted...");
            logger.info("certs......: " + certs);
            logger.info("authType...: " + authType);
          }
        } };

    SSLContextBuilder sslBuilder = new SSLContextBuilder();
    sslBuilder.loadTrustMaterial(null, new TrustStrategy() {
      public boolean isTrusted(X509Certificate[] chain,
          String authType) throws CertificateException {
        return true;
      }
    });

    @SuppressWarnings("deprecation")
    HostnameVerifier hostnameVerifier = 
			SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER;
    SSLConnectionSocketFactory sslSocketFactory = 
			new SSLConnectionSocketFactory(sslBuilder.build(), hostnameVerifier);
    CloseableHttpClient client = HttpClients.custom()
        .setSSLSocketFactory(sslSocketFactory).build();
    HttpGet httpget = new HttpGet(URLAddress);

    logger.info("Executing request " + httpget.getRequestLine());

    // Set up the response handler
    ResponseHandler<String> handler = new ResponseHandler<String>() {
      @Override
      public String handleResponse(final HttpResponse response)
          throws ClientProtocolException, IOException {

        int status = response.getStatusLine().getStatusCode();

        logger.info("Status: " + status);
        if (status >= 200 && status < 300) {
          HttpEntity entity = response.getEntity();
          return entity != null ? EntityUtils.toString(entity) : null;
        } else {
          throw new ClientProtocolException(
              "Unexpected response status: " + status);
        }
      }
    };
    String responseBody = client.execute(httpget, handler);
    return responseBody;
  }
}

Testing out using ApacheHttpClientTest

package com.avaldes.test;

import java.io.IOException;
import java.net.MalformedURLException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;

import com.avaldes.util.ApacheConnection;

public class ApacheHttpClientTest {
	public static void main(String[] args)
			throws MalformedURLException {

		CommandLineParser parser = new DefaultParser();
		Option help = new Option("help", "print this message");

		Options options = new Options();
		options.addOption(help);
		try {
			CommandLine cmd = parser.parse(options, args);

			if (cmd.hasOption("help")) {
				System.out.println("This help message...");
			}

		} catch (ParseException e) {
			System.err
					.println("Unable to parse command-line options -- Reason: "
							+ e.getMessage());
		}

		ApacheConnection apacheConnection = new ApacheConnection();

		// Test HTTP GET method
		Map<String, String> headers = new HashMap<String, String>();
		headers.put("header1", "headerValue1");
		headers.put("header2", "headerValue2");
		String response = apacheConnection
				.executeGet("http://httpbin.org/get", headers);
		System.out.println(response);

		// Test HTTP POST method
		List<NameValuePair> postParams = new ArrayList<NameValuePair>();
		postParams.add(new BasicNameValuePair("param1", "paramValue1"));
		postParams.add(new BasicNameValuePair("param2", "paramValue2"));
		postParams.add(new BasicNameValuePair("param3", "paramValue3"));
		response = apacheConnection.executePost("http://httpbin.org/post",
				null, postParams);
		System.out.println(response);

		// Test HTTPS GET method
		try {
			response = apacheConnection
					.executeSSLGet("https://httpbin.org/get", null);
		} catch (KeyManagementException | NoSuchAlgorithmException
				| KeyStoreException | IOException e) {
			e.printStackTrace();
		}
		System.out.println(response);

		// Test HTTPS POST method
		postParams = new ArrayList<NameValuePair>();
		postParams.add(new BasicNameValuePair("param1", "paramValue1"));
		postParams.add(new BasicNameValuePair("param2", "paramValue2"));
		postParams.add(new BasicNameValuePair("param3", "paramValue3"));
		try {
			response = apacheConnection.executeSSLPost(
					"https://httpbin.org/post", null, postParams);
		} catch (KeyManagementException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (KeyStoreException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		System.out.println(response);

	}
}

Output from executeGet

INFO : com.avaldes.util.ApacheConnection - Status: 200
{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip,deflate", 
    "Header1": "headerValue1", 
    "Header2": "headerValue2", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/4.5 (Java/1.7.0_79)"
  }, 
  "url": "http://httpbin.org/get"
}

Output from executePost

INFO : com.avaldes.util.ApacheConnection - Status: 200
{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Accept-Encoding": "gzip,deflate", 
    "Content-Length": "0", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/4.5 (Java/1.7.0_79)"
  }, 
  "json": null, 
  "url": "http://httpbin.org/post"
}

Output from executeSSLGet

INFO : com.avaldes.util.ApacheConnection - 
		Executing request GET https://httpbin.org/get HTTP/1.1
INFO : com.avaldes.util.ApacheConnection - Status: 200
{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip,deflate", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/4.5 (Java/1.7.0_79)"
  }, 
  "url": "https://httpbin.org/get"
}

Output from executeSSLPost

INFO : com.avaldes.util.ApacheConnection - Status: 200
{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {
    "param1": "paramValue1",
    "param2": "paramValue2",
    "param3": "paramValue3"
  }, 
  "headers": {
    "Accept-Encoding": "gzip,deflate", 
    "Content-Length": "56", 
    "Content-Type": "application/x-www-form-urlencoded; charset=UTF-8", 
    "Host": "httpbin.org", 
    "User-Agent": "Apache-HttpClient/4.5 (Java/1.7.0_79)"
  }, 
  "json": null, 
  "url": "https://httpbin.org/post"
}

Download the Complete Source Code

That’s It!

I hope you enjoyed this tutorial. It was certainly a lot of fun putting it together and testing it out. Please continue to share the love and like us so that we can continue bringing you quality tutorials. Happy Coding!!!

apacheHttpClient

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Written by

Amaury holds a Masters degree in Computer Science and is a passionate Senior Java Software Engineer and Architect. He founded avaldes.com in late 2008 as a forum to share ideas and passion for Java, Spring, Jax-RS, REST, AngularJS, ExtJS, MongoDB, Sybase, Oracle. and DB2 He has good experience in Java/J2EE Web-Application development for Banking, Telecom, Retail and E-Commerce Domains. He is also very passionate about fitness and weight training.

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