jersey client framework

Simple client to invoke a GET request

package client;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;


public class CleintGet {
	public static void main(String[] args) {
		try {
			//create a client object for consuming the REST response
			Client client = ClientBuilder.newClient();
			
			//the REST URL you want to connect to
			WebTarget target = client.target("http://hit.run.aws-usw02-pr.ice.predix.io/rest/myresource/999999999999,111111111111");

			//tell the service you are connecting to that you accept JSON
			//and invoke the GET
			Response response = target.request(MediaType.APPLICATION_JSON_TYPE).get();

			//responseStr now holds the response from the REST service
			String responseStr = response.readEntity(String.class);

			System.out.println(responseStr);
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

TRYIT: Modify this code to get a song by id, ex: http://localhost:8080/unh/rest/song/3


The WebTarget can be reused by specifying a root of the service and then appending it with "path" string

WebTarget target = client.target("http://localhost:8080/unh/rest");
Response response = target.path("song").request(MediaType.APPLICATION_JSON_TYPE).get();

TRYIT: Modify your application to use the path method for target

locating resource and adding query parameter:

WebTarget target = client.target("http://api.openweathermap.org/data/2.5");
Response response = target.path("weather").queryParam("q","London,uk").request(MediaType.APPLICATION_JSON_TYPE).get();

Passing more query parameters and parsing the output:

package client;

import java.util.HashMap;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.databind.ObjectMapper;

public class WeatherGet {
	@SuppressWarnings("unchecked")
	public static void main(String[] args) {
		try {
			Client client = ClientBuilder.newClient();

			WebTarget target = client
					.target("http://api.openweathermap.org/data/2.5");

			Response response = target.path("weather")
					.queryParam("q", "London,uk")
					.queryParam("units", "metric")
					.queryParam("APPID", "b504dd6600d713651dc073eb660a2664")
					.request(MediaType.APPLICATION_JSON_TYPE).get();

			String responseStr = response.readEntity(String.class);
			try {
				ObjectMapper om = new ObjectMapper();
				
				HashMap<String, Object> hm = (HashMap<String, Object>) om
						.readValue(responseStr, HashMap.class);
				HashMap<String, Double> mainMap = (HashMap<String, Double>)hm.get("main");
				System.out.println(mainMap.get("temp"));
			} catch (Exception ex) {
				System.out.println("Could not parse the output");
				ex.printStackTrace();
			}

		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

a helpful tool for unmarshalling JSON to POJO: http://www.jsonschema2pojo.org/

An Example of parsing JSON response

package client;
import java.util.HashMap;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.databind.ObjectMapper;

public class HelloWeather {
	@SuppressWarnings("unchecked")
	public static void main(String[] args) {
		try {
			Client client = ClientBuilder.newClient();
			
			//http://api.openweathermap.org/data/2.5/weather?q=London,uk
			WebTarget target = client
					.target("http://api.openweathermap.org/data/2.5");

			Response response = target.path("weather")
					.queryParam("q", "London,uk").queryParam("units", "metric")
					.queryParam("APPID", "b504dd6600d713651dc073eb660a2664")
					.request(MediaType.APPLICATION_JSON_TYPE).get();

			String responseStr = response.readEntity(String.class);
			try {
				ObjectMapper om = new ObjectMapper();

				HashMap<String, Object> hm = (HashMap<String, Object>) om
						.readValue(responseStr, HashMap.class);
				Double temp = ((HashMap<String, Double>) hm.get("main"))
						.get("temp");
				String name = (String)hm.get("name");
				
				
				StringBuilder sb = new StringBuilder();
				sb.append("Hello ");
				sb.append(name);
				sb.append(" it's ");
				sb.append(temp);
				sb.append(" degrees C");
				System.out.println(sb);

			} catch (Exception ex) {
				System.out.println("Could not parse the output");
				ex.printStackTrace();
			}

		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

Hello London it's 7.9 degrees C

post client

package client;

import java.util.HashMap;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.fasterxml.jackson.databind.ObjectMapper;


public class PostBook {
	public static void main(String[] args) {
		try {
			Client client = ClientBuilder.newClient();

			WebTarget target = client.target("http://localhost:8080/jersey_mongo/rest");
			
			HashMap<String, Object> hm = new HashMap<String, Object>();
			hm.put("title", "BOOK_POST");
			hm.put("author", "AUTHOR_POST");
			ObjectMapper om = new ObjectMapper();
			
			Response r = target.path("books").request(MediaType.APPLICATION_JSON_TYPE).post(
					Entity.entity(om.writeValueAsString(hm), MediaType.APPLICATION_JSON_TYPE));


			System.out.println(r.getStatus());
			System.out.println(r.readEntity(String.class));
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

DELETE Client

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

public class ClientDelete {
	public static void main(String[] args) {
		try {
			Client client = ClientBuilder.newClient();

			WebTarget target = client.target("http://localhost:8080/unh/rest");

			Response r = target.path("song").path("9")
					.request(MediaType.APPLICATION_JSON_TYPE).delete();

			System.out.println(r.getStatus());
			System.out.println(r.readEntity(String.class));
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

TRYIT: write update client