Send HTTP Get Request in Java

The post will give two examples to send HTTP GET requests using Java standard API or using Apache HttpClient.

1. The example using Java API URLConnection


package net.tecbar.examples;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;

public class HttpGetExamples1 {

	public String sendGetRequest() {
        final StringBuilder response = new StringBuilder();
        
        try {
        	// pass parameters in GET request
        	final StringBuilder apiURL = new StringBuilder("http://tecbar.net/demo/param?name=tecbar&group=middleschool");
        	// apiURL.append("&XML=" + URLEncoder.encode("<name>Tina Limo</name><id>466545</id>", "UTF-8"));
            
        	final URL url = new URL(apiURL.toString());
            final URLConnection conn = url.openConnection();
            conn.addRequestProperty("Accept-Language", "en-us");
            conn.addRequestProperty("Accept-Encoding", "gzip,deflate");
            conn.addRequestProperty("Accept-Charset", "ISO-8859-1,utf-8");
            conn.addRequestProperty("Keep-Alive", "300");
            conn.setConnectTimeout(2500);  // in milliseconds

            // Read all the text returned by the server
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String str;
            while ((str = in.readLine()) != null) {
                response.append(str);
            }
            in.close();
        }
        catch(IOException ex) {
            // process your exception here
        }
		
		return response.toString();
	}
	
	public static void main(String[] args) {
		final HttpGetExamples1 instance = new HttpGetExamples1();
		final String response = instance.sendGetRequest();
		
		System.out.println("response :" + response);
	}

}

package net.tecbar.examples;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.URL;

import java.net.URLConnection;

public class HttpGetExamples1 {

public String sendGetRequest() {

final StringBuilder response = new StringBuilder();

try {

// pass parameters in GET request

final StringBuilder apiURL = new StringBuilder("http://tecbar.net/demo/param?name=tecbar&group=middleschool");

// apiURL.append("&XML=" + URLEncoder.encode("<name>Tina Limo</name><id>466545</id>", "UTF-8"));

final URL url = new URL(apiURL.toString());

final URLConnection conn = url.openConnection();

conn.addRequestProperty("Accept-Language", "en-us");

conn.addRequestProperty("Accept-Encoding", "gzip,deflate");

conn.addRequestProperty("Accept-Charset", "ISO-8859-1,utf-8");

conn.addRequestProperty("Keep-Alive", "300");

conn.setConnectTimeout(2500); // in milliseconds

// Read all the text returned by the server

BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));

String str;

while ((str = in.readLine()) != null) {

response.append(str);

}

in.close();

}

catch(IOException ex) {

// process your exception here

}

return response.toString();

}

public static void main(String[] args) {

final HttpGetExamples1 instance = new HttpGetExamples1();

final String response = instance.sendGetRequest();

System.out.println("response :" + response);

}

2. The example using Apache HttpClient (4.x)


package net.tecbar.examples;

import java.io.IOException;

import org.apache.http.HttpEntity;
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;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

public class HttpGetExamples2 {
	private final String USER_AGENT = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) Version/7.0.3 Safari/7046A194A";
	
	public String sendGetRequest() {
		final StringBuilder apiURL = new StringBuilder("http://tecbar.net/demo/param?name=tecbar&group=middleschool");
		String response = "";
		
		// DefaultHttpClient is deprecated
		HttpClient httpclient = HttpClientBuilder.create().build();  
        HttpGet httpget = new HttpGet(apiURL.toString());
        httpget.setHeader(HTTP.USER_AGENT, USER_AGENT);
		try {
			HttpResponse httpResponse = httpclient.execute(httpget);
			HttpEntity entity = httpResponse.getEntity();
			response = EntityUtils.toString(entity) ;            
		} catch (IOException e) {
			// process your exception here
		}
		
		return response;
	}
	
	public static void main(String[] args) {
		final HttpGetExamples2 instance = new HttpGetExamples2();
		final String response = instance.sendGetRequest();
		
		System.out.println("response :" + response);
	}
}