How do I execute HTTP Get request?

By Wayan in Apache HttpComponents 0 Comment

Below is an example using HttpClient library to retrieve the content of a website using Http Get request. We start by creating an instance of DefaultHttpClient class. We then define an Http get request by create an instance of HttpGet class and specify the Url of a website we are going to retrieve.

To execute the request we call the HttpClient.execute() method and pass the HttpGet as the arguments. This execution return an HttpResponse object. From this response object we can read the content of the website by accessing the getEntity().getContent() which will give us an InputStream to the content.

For more detail let’s see the code snippet below:

package org.kodejava.example.httpclient;

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 java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class HttpGetExample {
    public static void main(String[] args) {
        HttpClient client = HttpClientBuilder.create().build();
        HttpGet request = new HttpGet("https://kodejava.org");

        try {
            HttpResponse response = client.execute(request);
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                try (InputStream stream = entity.getContent()) {
                    BufferedReader reader =
                            new BufferedReader(new InputStreamReader(stream));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        System.out.println(line);
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<!-- http://repo1.maven.org/maven2/org/apache/httpcomponents/httpclient/4.5.3/httpclient-4.5.3.jar -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
</dependency>

How do I get HTTP response body as a string?

By Wayan in Apache HttpComponents 2 Comments

This example show you how to get HTTP response body as a string when using the Apache HttpComponents library. To get the response body as a string we can use the EntityUtils.toString() method. This method read the content of an HttpEntity object content and return it as a string. The content will be converted using the character set from the entity object.

Let’s see the code snippet below:

package org.kodejava.example.httpclient;

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.util.EntityUtils;

import java.io.IOException;

public class EntityAsString {
    public static void main(String[] args) {
        HttpClient client = HttpClientBuilder.create().build();
        HttpGet request = new HttpGet("https://kodejava.org");

        try {
            HttpResponse response = client.execute(request);
            HttpEntity entity = response.getEntity();

            // Read the contents of an entity and return it as a String.
            String content = EntityUtils.toString(entity);
            System.out.println(content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<!-- http://repo1.maven.org/maven2/org/apache/httpcomponents/httpclient/4.5.3/httpclient-4.5.3.jar -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
</dependency>