Spring MVC Project - Retrieving Population, Area and Region Details using Rest API

Last Updated : 28 Sep, 2022

REST API is more popular nowadays as we can able to get a variety of information like Population, Area, region, sub-region, etc., One such REST API that we are going to see here is

https://restcountries.com/v3.1/capital/<any capital of a country>

Example:

https://restcountries.com/v3.1/capital/delhi

Corresponding JSON Response:

As a Maven Spring MVC project, let us see how to get the details and render in screen

Project Structure:

pom.xml

Let us see the main configuration as well as the Controller file

AppConfig.java

Java

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;  @Configuration @EnableWebMvc @ComponentScan(basePackages = { "com.country.Country_Rest_API" }) public class AppConfig {      @Bean     public InternalResourceViewResolver resolver() {         InternalResourceViewResolver resolver = new InternalResourceViewResolver();         resolver.setViewClass(JstlView.class);         resolver.setPrefix("/");         resolver.setSuffix(".jsp");         return resolver;     }  }

SpringMvcDispatcherServletInitializer.java

Java

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;  public class SpringMvcDispatcherServletInitializer extends           AbstractAnnotationConfigDispatcherServletInitializer {       @Override     protected Class<?>[] getRootConfigClasses() {         return null;     }       @Override     protected Class<?>[] getServletConfigClasses() {         return new Class[] { AppConfig.class };     }       @Override     protected String[] getServletMappings() {         return new String[] { "/" };     }   }

CountryController.java

Java

import com.google.gson.Gson; import com.google.gson.JsonArray; 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 org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody;  @Controller public class CountryController {      @RequestMapping("/getCountryDetailsByCapital")     public @ResponseBody     JsonObject getCountryDetailsByCapital(String capital)         throws IOException     {          JsonObject jsonObject = new JsonObject();         jsonObject = getDetails(capital);         JsonObject outputJsonObject = new JsonObject();         capital = jsonObject.get("capital").toString();         String region = jsonObject.get("region").toString();         String subRegion             = jsonObject.get("subregion").toString();         String area = jsonObject.get("area").toString();         String population             = jsonObject.get("population").toString();          outputJsonObject.addProperty("capital", capital);         outputJsonObject.addProperty("region", region);         outputJsonObject.addProperty("subRegion",                                      subRegion);         outputJsonObject.addProperty("area", area);         outputJsonObject.addProperty("population",                                      population);          return outputJsonObject;     }      private JsonObject getDetails(String capital)         throws IOException     {          StringBuilder responseData = new StringBuilder();         JsonArray jsonArray = null;         URL url = null;         url = new URL(             "https://restcountries.com/v3.1/capital/"             + capital);         JsonObject jsonObject = null;         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);         try (BufferedReader in              = new BufferedReader(new InputStreamReader(                  con.getInputStream()))) {              String line;              while ((line = in.readLine()) != null) {                 responseData.append(line);             }              jsonArray = new Gson().fromJson(                 responseData.toString(), JsonArray.class);             jsonObject = jsonArray.get(0).getAsJsonObject();         }         return jsonObject;     } }

index.jsp

HTML

<!DOCTYPE html> <html lang="en">    <head>       <meta charset="utf-8">       <meta http-equiv="X-UA-Compatible" content="IE=edge">       <meta name="viewport" content="width=device-width, initial-scale=1">       <title>CountryDetails</title>       <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css">       <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>       <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>       <style type="text/css">          .main-form, .profile-area {          width: 340px;          }          .main-form {          margin: 50px auto 0px;          }          .profile-area {          margin: 10px auto;          }          .main-form section, .profile-area section {          margin-bottom: 15px;          background: #f7f7f7;          box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);          }          .main-form section {          padding: 30px;          }          .profile-area section {          padding: 30px 30px 30px;          }          .profile-area section > div {          text-align: center;          }          .main-form h3 {          margin: 0 0 15px;          }          .form-control, .btn {          min-height: 38px;          border-radius: 2px;          }          .btn {          font-size: 15px;          font-weight: bold;          }          .hideElement {          display: none;          }       </style>    </head>    <body>       <div class="main-form" id="main-form">          <section>             <h5 class="text-center">Enter your capital</h5>             <div class="form-group">                <input id="capital" type="text" class="form-control" placeholder="Enter capital here..." required="required">             </div>             <div class="form-group">                <button onclick="loadData()" class="btn btn-primary btn-block">Find Capital Details</button>             </div>          </section>       </div>       <div class="profile-area hideElement" id="profile-area">          <section>             <div id="loader" class="hideElement">                <div class="spinner-border" role="status">                   <span class="sr-only">Loading...</span>                </div>             </div>             <div id="profile" class="hideElement">                <br><br>                <p><strong>Region    : </strong><span id="region"></span></p>                <p><strong>SubRegion : </strong><span id="subRegion"></span></p>                <p><strong>Area      : </strong><span id="area"></span></p>                <p><strong>Population: </strong><span id="population"></span></p>             </div>          </section>       </div>    </body>    <script>       function loadData() {           document.getElementById("profile-area").classList.remove("hideElement");           document.getElementById("loader").classList.remove("hideElement");           document.getElementById("profile").classList.add("hideElement");                  var capital = document.getElementById("capital").value;              var otherCurrency1,otherCurrency2;           if(capital != "" && capital != null) {               var xhttp = new XMLHttpRequest();               xhttp.onreadystatechange = function() {                   if (this.readyState == 4 && this.status == 200) {                       var jsonResponse = JSON.parse(this.responseText);                       document.getElementById("capital").innerHTML = jsonResponse.capital;                       document.getElementById("region").innerHTML = jsonResponse.region;                       document.getElementById("subRegion").innerHTML = jsonResponse.subRegion;                       document.getElementById("area").innerHTML = jsonResponse.area;                       document.getElementById("population").innerHTML = jsonResponse.population;                                            document.getElementById("loader").classList.add("hideElement");                       document.getElementById("profile").classList.remove("hideElement");                   }               };               xhttp.open("GET", "getCountryDetailsByCapital?capital=" + capital, true);               xhttp.send();               console.log("done");           } else {               console.log("Enter capital...")           }       }    </script> </html>

On running index.jsp:

Output:

We can find the detail for any capital. Actually, only a few pieces of information are shown here. But as mentioned in the JSON response, the details are retrieved.

Spring MVC Project - Retrieving Population, Area and Region Details using Rest API

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Spring MVC Project - Retrieving Population, Area and Region Details using Rest API

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