Apache HttpClient is a robust and complete solution Java library to perform HTTP operations, including RESTful service. In this tutorial, we show you how to create a RESTful Java client with Apache HttpClient, to perform a “GET” and “POST” request.
Note
The RESTful services from last “Jackson + JAX-RS” article will be reused.
1. Get Apache HttpClient
Apache HttpClient is available in Maven central repository, just declares it in your Maven pom.xml file.
File : pom.xml
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.1.1</version> </dependency>
2. GET Request
Review last REST service again.
@Path("/json/product")
public class JSONService {
@GET
@Path("/get")
@Produces("application/json")
public Product getProductInJSON() {
Product product = new Product();
product.setName("iPad 3");
product.setQty(999);
return product;
}
//...
Apache HttpClient to send a “GET” request.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
public class ApacheHttpClientGet {
public static void main(String[] args) {
try {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet getRequest = new HttpGet(
"http://localhost:8080/RESTfulExample/json/product/get");
getRequest.addHeader("accept", "application/json");
HttpResponse response = httpClient.execute(getRequest);
if (response.getStatusLine().getStatusCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatusLine().getStatusCode());
}
BufferedReader br = new BufferedReader(
new InputStreamReader((response.getEntity().getContent())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}
httpClient.getConnectionManager().shutdown();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output…
Output from Server ....
{"qty":999,"name":"iPad 3"}3. POST Request
Review last REST service also.
@Path("/json/product")
public class JSONService {
@POST
@Path("/post")
@Consumes("application/json")
public Response createProductInJSON(Product product) {
String result = "Product created : " + product;
return Response.status(201).entity(result).build();
}
//...
Apache HttpClient to send a “POST” request.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
public class ApacheHttpClientPost {
public static void main(String[] args) {
try {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost postRequest = new HttpPost(
"http://localhost:8080/RESTfulExample/json/product/post");
StringEntity input = new StringEntity("{\"qty\":100,\"name\":\"iPad 4\"}");
input.setContentType("application/json");
postRequest.setEntity(input);
HttpResponse response = httpClient.execute(postRequest);
if (response.getStatusLine().getStatusCode() != 201) {
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatusLine().getStatusCode());
}
BufferedReader br = new BufferedReader(
new InputStreamReader((response.getEntity().getContent())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}
httpClient.getConnectionManager().shutdown();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output…
Output from Server ....
Product created : Product [name=iPad 4, qty=100]Download Source Code
$ git clone https://github.com/favtuts/java-jax-rs-tutorials.git
$ cd jax-rs-apache-httpclient-example