How to consume REST in Java
JavaWeb ServicesRestJava Problem Overview
Using Java tools,
wscompile for RPC
wsimport for Document
etc..
I can use WSDL to generate the stub and Classes required to hit the SOAP Web Service.
But I have no idea how I can do the same in REST. How can I get the Java classes required for hitting the REST Web Service. What is the way to hit the service anyway?
Can anyone show me the way?
Java Solutions
Solution 1 - Java
Working example, try this:
package restclient;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class NetClientGet {
public static void main(String[] args) {
try {
URL url = new URL("http://localhost:3002/RestWebserviceDemo/rest/json/product/dynamicData?size=5");//your url i.e fetch data from .
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP Error code : "
+ conn.getResponseCode());
}
InputStreamReader in = new InputStreamReader(conn.getInputStream());
BufferedReader br = new BufferedReader(in);
String output;
while ((output = br.readLine()) != null) {
System.out.println(output);
}
conn.disconnect();
} catch (Exception e) {
System.out.println("Exception in NetClientGet:- " + e);
}
}
}
Solution 2 - Java
As others have said, you can do it using the lower level HTTP API, or you can use the higher level JAXRS APIs to consume a service as JSON. For example:
Client client = ClientBuilder.newClient();
WebTarget target = client.target("http://host:8080/context/rest/method");
JsonArray response = target.request(MediaType.APPLICATION_JSON).get(JsonArray.class);
Solution 3 - Java
Its just a 2 line of code.
import org.springframework.web.client.RestTemplate;
RestTemplate restTemplate = new RestTemplate();
YourBean obj = restTemplate.getForObject("http://gturnquist-quoters.cfapps.io/api/random", YourBean.class);
Solution 4 - Java
The code below will help to consume rest api via Java. URL - end point rest If you dont need any authentication you dont need to write the authStringEnd variable
The method will return a JsonObject with your response
public JSONObject getAllTypes() throws JSONException, IOException {
String url = "/api/atlas/types";
String authString = name + ":" + password;
String authStringEnc = new BASE64Encoder().encode(authString.getBytes());
javax.ws.rs.client.Client client = ClientBuilder.newClient();
WebTarget webTarget = client.target(host + url);
Invocation.Builder invocationBuilder = webTarget.request(MediaType.APPLICATION_JSON).header("Authorization", "Basic " + authStringEnc);
Response response = invocationBuilder.get();
String output = response.readEntity(String.class
);
System.out.println(response.toString());
JSONObject obj = new JSONObject(output);
return obj;
}
Solution 5 - Java
Just make an http request to the required URL with correct query string, or request body.
For example you could use java.net.HttpURLConnection
and then consume via connection.getInputStream()
, and then covnert to your objects.
In spring there is a restTemplate
that makes it all a bit easier.
Solution 6 - Java
If you also need to convert that xml string that comes as a response to the service call, an x object you need can do it as follows:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.JAXB;
import javax.xml.bind.JAXBException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.CharacterData;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
public class RestServiceClient {
// http://localhost:8080/RESTfulExample/json/product/get
public static void main(String[] args) throws ParserConfigurationException,
SAXException {
try {
URL url = new URL(
"http://localhost:8080/CustomerDB/webresources/co.com.mazf.ciudad");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/xml");
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
Ciudades ciudades = new Ciudades();
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println("12132312");
System.err.println(output);
DocumentBuilder db = DocumentBuilderFactory.newInstance()
.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(output));
Document doc = db.parse(is);
NodeList nodes = ((org.w3c.dom.Document) doc)
.getElementsByTagName("ciudad");
for (int i = 0; i < nodes.getLength(); i++) {
Ciudad ciudad = new Ciudad();
Element element = (Element) nodes.item(i);
NodeList name = element.getElementsByTagName("idCiudad");
Element element2 = (Element) name.item(0);
ciudad.setIdCiudad(Integer
.valueOf(getCharacterDataFromElement(element2)));
NodeList title = element.getElementsByTagName("nomCiudad");
element2 = (Element) title.item(0);
ciudad.setNombre(getCharacterDataFromElement(element2));
ciudades.getPartnerAccount().add(ciudad);
}
}
for (Ciudad ciudad1 : ciudades.getPartnerAccount()) {
System.out.println(ciudad1.getIdCiudad());
System.out.println(ciudad1.getNombre());
}
conn.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static String getCharacterDataFromElement(Element e) {
Node child = e.getFirstChild();
if (child instanceof CharacterData) {
CharacterData cd = (CharacterData) child;
return cd.getData();
}
return "";
}
}
Note that the xml structure that I expected in the example was as follows:
<ciudad><idCiudad>1</idCiudad><nomCiudad>BOGOTA</nomCiudad></ciudad>
Solution 7 - Java
Solution 8 - Java
JAX-RS but you can also use regular DOM that comes with standard Java
Solution 9 - Java
From your question its not clear whether you are using any frameworks.For REST you will be getting an WADL & Apache CXF recently added support for WADL-first development of REST services.Please go through http://cxf.apache.org/docs/index.html
Solution 10 - Java
You can able to consume a Restful Web service in Spring using RestTemplate.class.
Example :
public class Application {
public static void main(String args[]) {
RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> call= restTemplate.getForEntity("http://localhost:8080/SpringExample/hello",String.class);
System.out.println(call.getBody())
}
}
Solution 11 - Java
Apache Http Client APIs are very commonly used for calling HTTP Rest services.
Here is one of example of consuming HTTP GET call.
import java.io.IOException;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.impl.client.HttpClientBuilder;
public class CallHTTPGetService {
public static void main(String[] args) throws ClientProtocolException, IOException {
HttpClient client = HttpClientBuilder.create().build();
HttpUriRequest httpUriRequest = new HttpGet("URL");
HttpResponse response = client.execute(httpUriRequest);
System.out.println(response);
}
}
Use following maven dependency if using Maven project.
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.1</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpmime -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.5.1</version>
</dependency>