Wednesday 13 March 2013

Apache HttpClient Get Post

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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]

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