How to Call Restfull API Using Java

Following post I am going to explain how to call Restful API using java and retrieve data

import java.io.BufferedReader;

import java.io.FileInputStream;

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.security.KeyStore;

import java.security.KeyStoreException;

import javax.net.SocketFactory;

import javax.net.ssl.HttpsURLConnection;

import javax.net.ssl.KeyManagerFactory;

import javax.net.ssl.SSLContext;

import javax.net.ssl.SSLSocketFactory;

import javax.net.ssl.TrustManager;

import javax.net.ssl.TrustManagerFactory;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;

import org.xml.sax.InputSource;

import org.apache.commons.lang.StringUtils;

import org.json.simple.*;

import org.json.simple.parser.JSONParser;

public class RstAPICall {

                                public static void main(String[] args) {

                                  try {

                                                URL url = new URL("Enter your Restful API url");

                                                HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();

                                               

                                                SocketFactory factory = SSLSocketFactory.getDefault()

                                                conn.setSSLSocketFactory();

                                                //conn.

                                                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;

                                                System.out.println("Output from Server .... \n");

                                                 JSONParser parser = new JSONParser();

                                                while ((output = br.readLine()) != null) {

                                                                System.out.println(output);

                                                                OutputString=OutputString + output;

                                                                DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

                                                                InputSource src = new InputSource();

                                                                src.setCharacterStream(new StringReader(output));

                                                                Document doc = builder.parse(src);

                                               

                                        String SizeCode = StringUtils.substringBetween(output, "<SizeCode>","</SizeCode>");

                                        String SizeName = StringUtils.substringBetween(output, "<SizeWidthName>","</SizeWidthName>");

                                        String SizeDesc = StringUtils.substringBetween(output, "<SizeWidthDescription>","</SizeWidthDescription>");

                                        String NRFsize = StringUtils.substringBetween(output, "<SizeWidthNRF>","</SizeWidthNRF>");

                                       

                                        System.out.println("sizecode:"+SizeCode);

                                        System.out.println("sizename:"+SizeName);

                                        System.out.println("sizedesc:"+SizeDesc);

                                        System.out.println("nrfsize:"+NRFsize);

                                        //System.out.println();

                                         

                                                }

                                               

                                                conn.disconnect();

                                  } catch (MalformedURLException e) {

                                                e.printStackTrace();

                                  } catch (IOException e) {

                                                e.printStackTrace();

                                  } catch(Exception ex){}

                                }

}

Note:

URL url = new URL("Enter your Restful API url");

Enter your restfull API URL Details.

In this example I have retrieve data to xml format. If you want to get output as  Json

conn.setRequestProperty("Accept", "application/json");