OpenSource REST API URL and Retrieving Data From it By Using Spring MVC

// Java Program to Illustrate Application 
// configuration Class

// Importing required classes
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

// Annotations
@Configuration
@EnableWebMvc
@ComponentScan(basePackages
               = { "com.zipCode.zipCode_RestAPI" })

// Class
public class AppConfig {

    @Bean public InternalResourceViewResolver resolver()
    {

        InternalResourceViewResolver resolver
            = new InternalResourceViewResolver();
        resolver.setViewClass(JstlView.class);
        resolver.setPrefix("/");
        resolver.setSuffix(".jsp");

        return resolver;
    }
}

// Java Program to Illustrate
// SpringMvcDispatcherServletInitializer Class

// Importing required classes
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

// Class
public class SpringMvcDispatcherServletInitializer
    extends AbstractAnnotationConfigDispatcherServletInitializer {

    // Method 1
    @Override protected Class<?>[] getRootConfigClasses()
    {
        return null;
    }

    // Method 2
    @Override protected Class<?>[] getServletConfigClasses()
    {
        return new Class[] { AppConfig.class };
    }

    // Method 3
    @Override protected String[] getServletMappings()
    {
        return new String[] { "/" };
    }
}

// Java Program to Illustrate ZipCodeController Class

// Importing required classes
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

// Annotation
@Controller
// Class
public class ZipCodeController {

    // Method 1
    @RequestMapping("/getLocalityDetailsByZipCode")
    public @ResponseBody
    JsonObject getLocalityDetailsByZipCode(String zipCode)
        throws IOException
    {

        JsonObject jsonObject = new JsonObject();
        jsonObject = getLocalityDetailsByZip(zipCode);

        // Parsing the JSONObject
        JsonObject finalJsonObject = new JsonObject();

        String country
            = jsonObject.get("country").toString();
        country = country.replaceAll("^\"|\"$", "");
        JsonArray jsonPlacesArray = null;

        ArrayList placesList = new ArrayList();
        ArrayList stateList = new ArrayList();
        ArrayList latitudeList = new ArrayList();
        ArrayList longitudeList = new ArrayList();

        // Places data is available as JSONArray
        jsonPlacesArray
            = jsonObject.get("places").getAsJsonArray();
        // It is iterated
        Iterator<JsonElement> objectIterator
            = jsonPlacesArray.iterator();

        while (objectIterator.hasNext()) {
            JsonElement object = objectIterator.next();
            JsonObject jObj = object.getAsJsonObject();
            System.out.println(
                jObj.get("place name").toString()
                + jObj.get("state").toString());
            placesList.add(jObj.get("place name")
                               .toString()
                               .replaceAll("^\"|\"$", ""));
            stateList.add(
                jObj.get("state").toString().replaceAll(
                    "^\"|\"$", ""));
            latitudeList.add(
                jObj.get("latitude")
                    .toString()
                    .replaceAll("^\"|\"$", ""));
            longitudeList.add(
                jObj.get("longitude")
                    .toString()
                    .replaceAll("^\"|\"$", ""));
        }

        finalJsonObject.addProperty("country", country);
        finalJsonObject.addProperty("associatedplaces",
                                    placesList.toString());
        finalJsonObject.addProperty("associatedplacessize",
                                    placesList.size());
        finalJsonObject.addProperty("state",
                                    stateList.toString());
        finalJsonObject.addProperty(
            "statename", stateList.get(0).toString());
        finalJsonObject.addProperty(
            "associatedlatitude", latitudeList.toString());
        finalJsonObject.addProperty(
            "associatedlatitudesize", latitudeList.size());
        finalJsonObject.addProperty(
            "associatedlongitude",
            longitudeList.toString());
        finalJsonObject.addProperty(
            "associatedlongitudesize",
            longitudeList.size());

        return finalJsonObject;
    }

    // Method 2
    private JsonObject
    getLocalityDetailsByZip(String zipCode)
        throws IOException
    {

        String data = null;
        StringBuilder responseData = new StringBuilder();
        JsonObject jsonObject = null;

        URL url = null;
        url = new URL("http://api.zippopotam.us/IN/"
                      + zipCode);

        HttpURLConnection con
            = (HttpURLConnection)url.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("User-Agent", "Mozilla/5.0");
        int responseCode = con.getResponseCode();

        System.out.println(
            "\nSending 'GET' request to URL : " + url);
        //        System.out.println("Response Code : " +
        //        responseCode);

        // Try block to check for exceptions
        try (BufferedReader in
             = new BufferedReader(new InputStreamReader(
                 con.getInputStream()))) {

            String line;

            while ((line = in.readLine()) != null) {
                responseData.append(line);
            }

            jsonObject = new Gson().fromJson(
                responseData.toString(), JsonObject.class);
        }

        // System.out.println(data);
        return jsonObject;
    }
}