Spring Mvc Ajax Json Example | Spring Mvc Ajax Json Response Example

Project Dependencies


4.0.0


com.mkyong


spring4-mvc-maven-ajax-example
war
1.0-SNAPSHOT


spring4 mvc maven ajax example

1.8


4.2.2.RELEASE


2.6.3


1.1.3


1.7.12


1.2


3.1.0



org.springframework


spring-webmvc


${spring.version}




commons-logging


commons-logging







com.fasterxml.jackson.core


jackson-core


${jackson.version}




com.fasterxml.jackson.core


jackson-databind


${jackson.version}





javax.servlet


jstl


${jstl.version}





org.slf4j


jcl-over-slf4j


${jcl.slf4j.version}




ch.qos.logback


logback-classic


${logback.version}






javax.servlet


javax.servlet-api


${servletapi.version}


provided




org.apache.maven.plugins


maven-compiler-plugin


3.3


${jdk.version}

${jdk.version}


org.eclipse.jetty


jetty-maven-plugin


9.2.11.v20150529



10



/spring4ajax



org.apache.maven.plugins


maven-eclipse-plugin


2.10



true


true


2.0


spring4ajax


org.apache.maven.plugins


maven-war-plugin


2.6



false


org.wildfly.plugins


wildfly-maven-plugin


1.1.0.Alpha5



127.0.0.1
9990
admin
admin
spring4ajax.war



Example of Spring MVC Ajax JSON Response

In this section, we will go through an example of a Spring MVC Ajax JSON response. We will cover the environment setup, coding the application, and running and testing the application.

Setting Up the Environment

To set up the environment for this example, we need to have the following software installed:

• Java Development Kit (JDK)
• Eclipse IDE
• Apache Tomcat Server
• jQuery library

Once we have installed these software, we can proceed to the next step.

Coding the Application

In this step, we will create a simple Spring MVC application that will handle an Ajax request and return a JSON response.

1. Create a new Spring MVC project in Eclipse IDE.
2. In the
   
web.xml

   file, add the following configuration:




dispatcher


org.springframework.web.servlet.DispatcherServlet

contextConfigLocation /WEB-INF/dispatcher-servlet.xml



dispatcher




1. Create a
   
dispatcher-servlet.xml

   file in the
   
WEB-INF

   directory and add the following configuration:

1. Create a new controller class named
   
AjaxController

   in the
   
com.example.controller

   package and add the following code:


@Controller public class AjaxController { @RequestMapping(value = "/ajax", method = RequestMethod.POST) public @ResponseBody Map

handleAjaxRequest() { Map

response = new HashMap

(); response.put("name", "John Doe"); response.put("age", 30); return response; } }





1. Create a new JSP file named
   
index.jsp

   in the
   
WEB-INF/views

   directory and add the following code:




Spring MVC Ajax JSON Response Example

Name:

Age:





Running and Testing the Application

To run and test the application, follow these steps:

1. Deploy the application on the Apache Tomcat server.
2. Open a web browser and navigate to
   
http://localhost:8080/spring-mvc-ajax-json-example/

   .
3. The page should display the name and age retrieved from the Ajax request.

That’s it! You have successfully created a Spring MVC Ajax JSON response example.

Download Source Code

References

About Author

Comments

Thanks. tutorial solved my problem

Thanks.This tutorial solved my problem

Hi Mkyong,I always found your examples clear and good,Thanks lot!

Hey guy, what example! So far the best tutorial i’ve ever seen. Thanks!!!

Thanks for the article . I am quite late but while working on this code, I get following issue.Multiple markers at this line– PostConstruct cannot be resolvedto a type– PostConstruct cannot be resolvedto a type

Anyone know how to resolve this?

Hi, is it possible to save an image in this way? how can I do it? Do you have any example? Thank you

Thank you mkYong for providing this good example.

I am able to deploy and start jetty with this project.

But I am getting below content on hitting http://localhost:2222/spring4ajax/ not showing search page.

Could you/someone please help me here.

Directory: /spring4ajax/spring4-mvc-maven-ajax-example-1.0-SNAPSHOT.war 13184243 bytes Apr 8, 2020 3:58:31 PM

method post not allowed

how to do CRUD operating in Spring MVC in eclipse without refreshing the page and connection with database

when i “$ mvn jetty:run “in the git bush it shows “No plugin found for prefix ‘jetty”‘

Could you please explain how can i do the same if i’m sending and receiving the data in XML instead of json?

Thanks

good tutorial, but i integration in my project and show this{“readyState”: 4,“responseText”: ”Estado HTTP 405 – Request method ‘POST’ not supportedtype Informe de estado

mensaje Request method ‘POST’ not supported

descripción El método HTTP especificado no está permitido para el recurso requerido.

Pivotal tc Runtime 3.1.5.RELEASE/8.0.36.A.RELEASE“,“status”: 405,“statusText”: “Método No Permitido”}

Could you please explain to me what the “$” sign mean in the following line:

jQuery(document).ready(function($) {And also why this line doesn’t start like:$(document) ?Thanks in advance!

this is a good example, thanks.

Hi Mkyong,

I have two questions. First, How to create layout file?And other question, Can we add annotation to validation for view class. i don’t want to write isValidSearchCriteria method.

thanks.

i got the following error while i execute the code …

The server refused this request because the request entity is in a format not supported by the requested resource for the requested method.

“status”: 415,

“statusText”: “Unsupported Media Type”

this is a good example, thanks.

Thanks

Hi Mkyoung,i’m getting this error :HTTP ERROR 406 Not Acceptable.

i’m sure that the ‘result’ object from ‘AjaxResponseBody’ class having a value when returned back to ajax response but i always get that error.

I’m using:– spring 4.0.2– jackson 2.6.3– jetty server

HI Mkyong,I’m uable to run this project in Tomcat 8, I mean the Tomcat starts properly with this project, but when I hit the url, it gives me 404.

Thanks,Kapil

Hi Mkyong,

Am trying to get this application up and running in JBoss AS7 but am getting a 404 when accessing http://localhost:8080/spring4ajax/search/api/getSearchResult/

I have the same issue with one of my application which works well in Tomcat but not in JBoss AS7, just wondering if there is a workaround if you know off.

Thanks

Article is updated with wildfly-maven-plugin, use this command

mvn wildfly:deploy

to deploy this web application to WildFly.

I am new in javawhere should I run this command

1. 404 is resources not found. Make sure ‘spring4ajax’ is your deployed web context.

2. If you get this example and deploy directly, the default web context will be this – http://localhst:8080/spring4-mvc-maven-ajax-example-1.0-SNAPSHOT

3. To update the WildFly web context, try this tutorial – https://mkyong.com/maven/maven-deploy-web-application-to-wildfly/

P.S This web application is tested with WildFly 9, no error.

hey guys , find given solution to compile the project.

you need to add following plugin in pom.xml

maven-war-plugin

2.4

false

Hope it would work for you guys , cheers 🙂

Thanks, article is updated with maven-war-plugin.

still can not work please help.HTTP Status 500 – An exception occurred processing JSP page /welcome.jsp at line 11

can you try that link after starting jetty servermake sure your port should not be used before.http://localhost:8080/spring4ajax/

It is not compiling:

Error assembling WAR: webxml attribute is required (or pre-existing WEB-INF/web.xml if executing in update mode) -> [Help 1]

Fixed, article is updated with maven-war-plugin.

Raul ,add this in your pom.xml

maven-war-plugin

2.4

false

Jeez, this is not a tutorial, but rather a template. It’s 400+ lines of code and merely a dozen lines of explanation.

Where is the web.xml file ? I have the following error:

org.xml.sax.SAXParseException; systemId: file:/C:/DEV/apache-tomcat-8.0.28/webapps/spring4-mvc-maven-ajax-example-1.0-SNAPSHOT/WEB-INF/web.xml; lineNumber: 1; columnNumber: 2; Premature end of file.

at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(Unknown Source)at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(Unknown Source)at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(Unknown Source)at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)

For servlet container >= 3, web.xml is option. Code is updated, try clone the source code from GitHub again.

you need to add following plugin in pom.xml

maven-war-plugin

2.4

false

Hi Mkyong,

I reckon that you will find that using my library http://www.ajaxanywhere.com makes things a lot easier with a far more maintainable outcome. Ajaxanywhere is intended to provide declarative Ajax for apps that use server side rendering. Because it is declarative, by using HTML markup, you will find that you use very llittle to none javascript code. Please have a look at the examples: http://examples.ajaxanywhere.comI would appreciate your feedback a lot!Thanks!

Good stuff, but you should keep it more simple. Some details are not really needed here. For example, the @JsonView annotation only confused me more untill I figured it has nothing to do with the scope of this presentation. Just skip it.Also, some details are maybe missing. For example, in order to work, I had to add an extention in ajax url (“url: getSearchResult.ext”) and then add this in web.xml:

dispatcher*.ext

servlet-mappingservlet-name dispatcher /servlet-nameurl-pattern *.ext /url-pattern/servlet-mapping

Spring MVC – Refactoring a jQuery Ajax Post example

Reviewing a jQuery Ajax form POST and Spring MVC example, find out the following patterns :

In Spring MVC, use

@RequestParam

to accept the Ajax POST data.


@RequestMapping(value = "/path-to/hosting/save", method = RequestMethod.POST) @ResponseBody public String saveHosting( @RequestParam int id, @RequestParam String domain, @RequestParam String name, @RequestParam String desc, @RequestParam String tags, @RequestParam String afflink, @RequestParam boolean display, @RequestParam boolean hosting, @RequestParam boolean cdn, @RequestParam boolean paas, @RequestParam String imageUrl, @RequestParam String favUrl, @RequestParam String whoisPattern ) { //...do something }


The above code is working fine, just a bit weird and hard to maintain. Both Javascript

$.post

and Spring MVC

@RequestParam

is dealing with too many parameters.

You just search Person: ” + data.name + “

“; $(“#ajax-response”).html(result); } else { var result = “

No person found

“; $(“#ajax-response”).html(result); } }, error : function(e) { console.log(“ERROR: “, e); } }); }

5)Demo
Bật terminal hoặc lên, đưa con trỏ vào vị trí của project và gõ lệnh

mvn jetty:run


**5.1) Nhập tên và tuổi **

**5.2) Kết quả ajax trả về từ server **

Ta đã sử dụng HTTP method GET nhưng dữ liệu vẫn k bị hiển thị lên url => việc nói POST bảo mật hơn GET vì dữ liệu không được đưa lên url là chưa đúng !


References

About Author

Comments

i sending formdata to controller class. in controller how to access these data?

$(“button#submitMDRtable”).click(function(){var data = [];var minAmt, maxAmt, type, minCap, maxCap;$(“table tbody tr”).each(function(index) {minAmt = $(this).find(‘.minAmt’).text();maxAmt = $(this).find(‘.maxAmt’).text();type = $(this).find(‘.type’).text();minCap = $(this).find(‘.minCap’).text();maxCap = $(this).find(‘.maxCap’).text();//alert(minAmt+”–“+maxAmt+”–“+type+”–“+minCap+”–“+maxCap)//—->Form validation goes heredata.push({minAmt: minAmt,maxAmt: maxAmt,type: type,minCap: minCap,maxCap: maxCap});});submitFormData(data);console.log(data);});

function submitFormData(formData) {var url= ‘/mdrcharges’;alert(url);$.ajax({type: ‘POST’,data: formData,cache: false,processData: false,contentType: false,beforeSend: beforeSendHandler,url: url,success: function(result){if(result.success == true) {$(‘.alert-success’).show();$(‘.alert-danger’).hide();$(“#successmsg”).html(result.msg);setTimeout(function() {$(“.alert-success”).alert(‘close’);}, 10000);} else {$(‘.alert-danger’).show();$(‘.alert-success’).hide();$(“#error”).html(result.msg);setTimeout(function() {$(“.alert-danger”).alert(‘close’);}, 10000);}}});}

OK. This is an easy example, and everyone saw it a hundred times. But tell us what do you will do if you have here is a JSON:

{“abc”:{“sr”:”ok”,”citi”:[{“id”:”c2″,”value”:”london”},{…}…,{…}]}}

etc ?

Just send a POST request, along with your JSON data.

<%@ page language=”java” contentType=”text/html; charset=ISO-8859-1″
pageEncoding=”ISO-8859-1″%>
<%@taglib prefix=”c” uri=”http://java.sun.com/jsp/jstl/core”%>

//CanvasjsChartController.java
package com.canvasjs.chart.controllers;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
@RequestMapping(“/canvasjschart”)
public class CanvasjsChartController {
@RequestMapping(method = RequestMethod.GET)
public String springMVC(ModelMap modelMap) {
return “chart”;
}
}
//RestController.java
package com.canvasjs.chart.controllers;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.canvasjs.chart.services.CanvasjsChartService;
@Controller
@RequestMapping(value = “/restfull-service”)
public class RestController extends HttpServlet {
private static final long serialVersionUID = 1L;
@Autowired
private CanvasjsChartService canvasjsChartService;
@RequestMapping(value = “/letter-frequency-of-vowels-in-english.json”, method = RequestMethod.GET)
public @ResponseBody String getDataPoints(HttpServletRequest request, HttpServletResponse response) throws Exception {
return canvasjsChartService.getCanvasjsChartData();
}
}

//CanvasjsChartService.java
package com.canvasjs.chart.services;
public interface CanvasjsChartService {
String getCanvasjsChartData();
}
//CanvasjsChartServiceImpl.java
package com.canvasjs.chart.services;
import org.springframework.beans.factory.annotation.Autowired;
import com.canvasjs.chart.daos.CanvasjsChartDao;
public class CanvasjsChartServiceImpl implements CanvasjsChartService {
@Autowired
private CanvasjsChartDao canvasjsChartDao;
public void setCanvasjsChartDao(CanvasjsChartDao canvasjsChartDao) {
this.canvasjsChartDao = canvasjsChartDao;
}
@Override
public String getCanvasjsChartData() {
return canvasjsChartDao.getCanvasjsChartData();
}
}

//CanvasjsChartDao.java
package com.canvasjs.chart.daos;
public interface CanvasjsChartDao {
String getCanvasjsChartData();
}
//CanvasjsChartDaoImpl.java
package com.canvasjs.chart.daos;
import com.canvasjs.chart.data.CanvasjsChartData;
public class CanvasjsChartDaoImpl implements CanvasjsChartDao {
@Override
public String getCanvasjsChartData() {
return CanvasjsChartData.getCanvasjsDataList();
}
}

//CanvasjsChartData.java
package com.canvasjs.chart.data;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.nio.charset.Charset;
import org.json.JSONException;
import org.json.JSONArray;
public class CanvasjsChartData {
static JSONArray json = null;
static {
try {
json = readJsonFromUrl(“https://canvasjs.com/data/gallery/spring-mvc/letter-frequency-of-vowels-in-english.json”);
} catch (Exception e) {
e.printStackTrace();
}
}
private static String readAll(Reader rd) throws IOException {
StringBuilder sb = new StringBuilder();
int cp;
while ((cp = rd.read()) != -1) {
sb.append((char) cp);
}
return sb.toString();
}
public static JSONArray readJsonFromUrl(String url) throws IOException, JSONException {
InputStream is = new URL(url).openStream();
try {
BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName(“UTF-8”)));
String jsonText = readAll(rd);
JSONArray json = new JSONArray(jsonText);
return json;
} finally {
is.close();
}
}
public static String getCanvasjsDataList() {
return json.toString();
}
}

Refactoring Spring MVC

2.1 Create a POJO to store the Ajax POST data.


public class HostingForm { private boolean display; private boolean cdn; private boolean hosting; private boolean paas; private String whoisPattern; private long id; private String domain; private String name; private String desc; private String tags; private String affLink; private String imageUrl; private String favUrl; //getters and setters


2.2 Accept the Ajax POST data with

@RequestBody



@RestController //... @RequestMapping(value = "/path-to/hosting/save", method = RequestMethod.POST) public String updateHosting(@RequestBody HostingForm hostingForm) { //... }


With

@RequestBody

, Spring will maps the POST data to

HostingForm

POJO (by name) automatically. Done.

You mat interest at this tutorial – Complete Spring 4 MVC + Ajax Form Post example

Common Issues and Solutions

Debugging Ajax Issues in Spring MVC

When working with Ajax requests in Spring MVC, it is common to encounter issues related to the request not being sent or received properly. Here are some common issues and solutions:

• Incorrect URL: Ensure that the URL in the Ajax request matches the URL in the Spring MVC controller. Check for any typos or missing slashes in the URL.
• Missing Request Parameters: Check if all the required request parameters are being sent in the Ajax request. Use the browser’s developer tools to inspect the request and response headers and data.
• Cross-Origin Resource Sharing (CORS): If the Ajax request is being sent from a different domain than the one hosting the Spring MVC application, then CORS restrictions may apply. Check if the server is configured to allow CORS requests.

Optimizing JSON Response

Sending JSON data in Spring MVC can be optimized to improve the performance of the application. Here are some tips to optimize the JSON response:

• Minimize the JSON payload: Only send the required data in the JSON response. Remove any unnecessary data to reduce the payload size.
• Use GZIP compression: Compress the JSON response using GZIP compression to reduce the payload size and improve the response time.
• Use caching: Cache the JSON response on the client-side or server-side to reduce the number of requests and improve the response time.

By following these tips, we can optimize the JSON response and improve the performance of the Spring MVC application.

Quick Reference

1.1 In HTML, use jQuery

$.ajax()

to send a form request.


jQuery(document).ready(function($) { $("#search-form").submit(function(event) { // Prevent the form from submitting via the browser. event.preventDefault(); searchViaAjax(); }); }); function searchAjax() { var data = {} data["query"] = $("#query").val(); $.ajax({ type : "POST", contentType : "application/json", url : "${home}search/api/getSearchResult", data : JSON.stringify(data), dataType : 'json', timeout : 100000, success : function(data) { console.log("SUCCESS: ", data); display(data); }, error : function(e) { console.log("ERROR: ", e); display(e); }, done : function(e) { console.log("DONE"); } }); }


1.2 Spring controller to handle the Ajax request.


@Controller public class AjaxController { @ResponseBody @RequestMapping(value = "/search/api/getSearchResult") public AjaxResponseBody getSearchResultViaAjax(@RequestBody SearchCriteria search) { AjaxResponseBody result = new AjaxResponseBody(); //logic return result; } }


Link download source code

https://www.dropbox.com/s/ov7wzcs49m3zgyx/viblo-spring-learn-ajax.zip?dl=0

All rights reserved

Spring 4 MVC Ajax Hello World Example

In this tutorial, we will show you how to create a Spring MVC web project and submit a form via Ajax.

Technologies used :

1. Spring 4.2.2.RELEASE
2. Jackson 2.6.3
3. Logback 1.1.3
4. jQuery 1.10.2
5. Maven 3
6. JDK 1.8
7. Tomcat 8 or Jetty 9
8. Eclipse 4.5
9. Boostrap 3

P.S If the Jackson library is found in the project classpath, Spring will use Jackson to handle the json data to / from object conversion automatically.

Try this – Spring Boot Ajax example

Spring Components

Only the important classes will be displayed.

4.1

@RestController

to handle the Ajax request. Read the comments for self-explanatory.


package com.mkyong.web.controller; import java.util.ArrayList; import java.util.List; import javax.annotation.PostConstruct; import org.springframework.util.StringUtils; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import com.fasterxml.jackson.annotation.JsonView; import com.mkyong.web.jsonview.Views; import com.mkyong.web.model.AjaxResponseBody; import com.mkyong.web.model.SearchCriteria; import com.mkyong.web.model.User; @RestController public class AjaxController { List

users; // @ResponseBody, not necessary, since class is annotated with @RestController // @RequestBody - Convert the json data into object (SearchCriteria) mapped by field name. // @JsonView(Views.Public.class) - Optional, filters json data to display. @JsonView(Views.Public.class) @RequestMapping(value = "/search/api/getSearchResult") public AjaxResponseBody getSearchResultViaAjax(@RequestBody SearchCriteria search) { AjaxResponseBody result = new AjaxResponseBody(); if (isValidSearchCriteria(search)) { List

users = findByUserNameOrEmail(search.getUsername(), search.getEmail()); if (users.size() > 0) { result.setCode("200"); result.setMsg(""); result.setResult(users); } else { result.setCode("204"); result.setMsg("No user!"); } } else { result.setCode("400"); result.setMsg("Search criteria is empty!"); } //AjaxResponseBody will be converted into json format and send back to the request. return result; } private boolean isValidSearchCriteria(SearchCriteria search) { boolean valid = true; if (search == null) { valid = false; } if ((StringUtils.isEmpty(search.getUsername())) && (StringUtils.isEmpty(search.getEmail()))) { valid = false; } return valid; } // Init some users for testing @PostConstruct private void iniDataForTesting() { users = new ArrayList

(); User user1 = new User("mkyong", "pass123", "[email protected]", "012-1234567", "address 123"); User user2 = new User("yflow", "pass456", "[email protected]", "016-7654321", "address 456"); User user3 = new User("laplap", "pass789", "[email protected]", "012-111111", "address 789"); users.add(user1); users.add(user2); users.add(user3); } // Simulate the search function private List

findByUserNameOrEmail(String username, String email) { List

result = new ArrayList

(); for (User user : users) { if ((!StringUtils.isEmpty(username)) && (!StringUtils.isEmpty(email))) { if (username.equals(user.getUsername()) && email.equals(user.getEmail())) { result.add(user); continue; } else { continue; } } if (!StringUtils.isEmpty(username)) { if (username.equals(user.getUsername())) { result.add(user); continue; } } if (!StringUtils.isEmpty(email)) { if (email.equals(user.getEmail())) { result.add(user); continue; } } } return result; } }








4.2 The “json data” will be converted into this object, via

@RequestBody

.


package com.mkyong.web.model; public class SearchCriteria { String username; String email; //getters and setters }


4.2 Create a dummy class for

@JsonView

, to control what should be returned back to the request.


package com.mkyong.web.jsonview; public class Views { public static class Public {} }


4.3 User object for search function. Fields which annotated with

@JsonView

will be displayed.


package com.mkyong.web.model; import com.fasterxml.jackson.annotation.JsonView; import com.mkyong.web.jsonview.Views; public class User { @JsonView(Views.Public.class) String username; String password; @JsonView(Views.Public.class) String email; @JsonView(Views.Public.class) String phone; String address; //getters, setters and contructors }


4.4 This object will be converted into json format and return back to the request.


package com.mkyong.web.model; import java.util.List; import com.fasterxml.jackson.annotation.JsonView; import com.mkyong.web.jsonview.Views; public class AjaxResponseBody { @JsonView(Views.Public.class) String msg; @JsonView(Views.Public.class) String code; @JsonView(Views.Public.class) List

result; //getters and setters }



The


@JsonViewbelongs to Jackson library, not Spring framework.


jQuery Ajax

In JSP, create a simple search form and send the form request with jQuery

$.ajax

.


<%@page session="false"%> <%@taglib prefix="spring" uri="http://www.springframework.org/tags"%> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>


Search Form

Username

Email

Search





Understanding Spring MVC

Spring MVC is a web application framework developed by the Spring Framework. It provides a model-view-controller (MVC) architecture that is used to develop web applications. The framework provides a lot of features that make the development of web applications easy and efficient. In this section, we will discuss the role of Spring MVC in web applications and its key features.

Role of Spring MVC in Web Applications

Spring MVC is a powerful framework that provides a lot of features that are essential for developing web applications. The framework provides a model-view-controller architecture that is used to separate the application into three parts:

• Model: This represents the data and business logic of the application.
• View: This represents the user interface of the application.
• Controller: This is responsible for handling the user requests, processing the data, and returning the response.

The main role of Spring MVC in web applications is to provide a flexible and powerful framework that can be used to develop web applications that are easy to maintain and extend. The framework provides a lot of features that make the development process easy and efficient.

Key Features of Spring MVC

Spring MVC provides a lot of key features that make it a powerful framework for developing web applications. Some of the key features are:

• Powerful Request Handling: Spring MVC provides a powerful request handling mechanism that can handle different types of requests, including GET, POST, PUT, DELETE, and more.
• Flexible Configuration: Spring MVC provides a flexible configuration mechanism that allows developers to configure the framework according to their needs.
• Built-in Validation: Spring MVC provides built-in validation support that allows developers to validate the user input easily.
• Internationalization Support: Spring MVC provides internationalization support that allows developers to develop applications that can be easily localized.
• Integration with Other Technologies: Spring MVC can be easily integrated with other technologies, such as Hibernate, MyBatis, and more.

In conclusion, Spring MVC is a powerful framework that provides a lot of features that make the development of web applications easy and efficient. The framework provides a model-view-controller architecture that is used to separate the application into three parts: model, view, and controller. The framework provides a lot of key features that make it a powerful framework for developing web applications.

Get ahead

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In my last entry, I walked you through several enhancements in Spring 3 for web application development. A number of you expressed interest in a follow-up entry focused on Ajax remoting. Spring 3 provides a lot in this area to take advantage of. Read on, and I’ll walk you through it.

For the purposes of this article, when I say Ajax, I’m talking about the web browser’s ability to communicate with a web server asynchronously using JavaScript. On the server-side, Spring provides the programming model for defining web services, including services consumed by JavaScript clients. On the client-side, nobody rolls their own Ajax framework these days, either. Most use an established JavaScript framework such as jQuery or Dojo.

Until version 3, Spring did not ship support for Ajax remoting. That didn’t stop our users from extending Spring to get it, or integrating other options themselves. Some used DWR, especially in the period before the rise of the JavaScript frameworks. More recently, REST-style remoting with JSON as the data exchange format has become more popular, especially because jQuery and co. make it so easy to do.

Now that Spring 3 is out, official support for Ajax remoting with JSON is provided as part of Spring MVC. This includes support for generating JSON responses and binding JSON requests using the Spring MVC @Controller programming model. In this article, I’m going to focus on using this support to implement several Ajax use cases. Like my last post, I’ll do this by walking you through a sample application you can experiment with yourself.

mvc-ajax has been designed to illustrate Spring MVC’s JSON support. The project is available in our spring-samples Subversion repository, is buildable with Maven, and is importable into STS / Eclipse. mvc-ajax has the same structure as the mvc-basic project presented in my previous entry. In fact, the Spring configuration is identical between the two.

Start your review by deploying the project to your servlet container and accessing the welcome page at localhost:8080/mvc-ajax. Since I use STS, I did this by first importing the project into the IDE, then deploying it to the built-in Tomcat / tc-server instance.

From the welcome page, activate the “Ajax @Controller Example” link. You will see a form to create a new Account. When you tab out of the Name field, your browser will ask the server if the name you just entered is available. If it is not, an error message will be displayed and the form will remain disabled until you enter a name that is available. The client-side JavaScript handling this resides in /WEB-INF/views/account/createForm.jsp and looks like:


$(document).ready(function() { // check name availability on focus lost $('#name').blur(function() { checkAvailability(); }); }); function checkAvailability() { $.getJSON("account/availability", { name: $('#name').val() }, function(availability) { if (availability.available) { fieldValidated("name", { valid : true }); } else { fieldValidated("name", { valid : false, message : $('#name').val() + " is not available, try " + availability.suggestions }); } }); }


Nothing Spring-specific here, just standard jQuery JavaScript.

On the server-side, the Controller for the account/availability resource is standard Java with some Spring MVC annotations:


@RequestMapping(value="/availability", method=RequestMethod.GET) public @ResponseBody AvailabilityStatus getAvailability(@RequestParam String name) { for (Account a : accounts.values()) { if (a.getName().equals(name)) { return AvailabilityStatus.notAvailable(name); } } return AvailabilityStatus.available(); }


AvailabilityStatus is a plain Java Value Object with two properties: an availability flag that tells the client if the user name is available, and an array of alternatives to suggest if the name you want is not available. The @ResponseBody annotation instructs Spring MVC to serialize the AvailabilityStatus to the client. Spring MVC automatically serializes to JSON because the client accepts that content type.

Underneath the covers, Spring MVC delegates to a HttpMessageConverter to perform the serialization. In this case, Spring MVC invokes a MappingJacksonHttpMessageConverter built on the Jackson JSON processor. This implementation is enabled automatically when you use the mvc:annotation-driven configuration element with Jackson present in your classpath.

Pretty cool, huh? Try creating an Account, then creating another one with the same name. You should see an error message suggesting alternate names. Turn on Firefox’s Firebug or Safari’s Web Inspector to debug the asynchronous interaction.

Spring MVC also provides support for sending JSON to the server. I have found the need for this to be less common, simply because posting form parameters is often sufficient. Nevertheless, JSON provides a flexible data-interchange format that richer JavaScript clients can conveniently work with. The ability to map JSON to a server-side Java Object for processing can be a useful feature in those cases.

In the sample, a JavaScript event handler intercepts the form submit event and posts the form data as JSON. The server returns the id of the newly created Account, which is then used to display a modal confirmation dialog:


$("#account").submit(function() { var account = $(this).serializeObject(); $.postJSON("account", account, function(data) { $("#assignedId").val(data.id); showPopup(); }); return false; });


On the server-side, the Controller is more standard Java with Spring MVC annotations:


@RequestMapping(method=RequestMethod.POST) public @ResponseBody Map

create(@RequestBody Account account, HttpServletResponse response) { Set

> failures = validator.validate(account); if (!failures.isEmpty()) { response.setStatus(HttpServletResponse.SC_BAD_REQUEST); return validationMessages(failures); } else { accounts.put(account.assignId(), account); return Collections.singletonMap("id", account.getId()); } }




Here, the @RequestBody annotation instructs Spring MVC to map the body of the HTTP request to an Account object. Spring MVC knows to map from JSON because the client set the request Content Type to application/json.

The create method also validates the Account object. If there are validation errors, a HTTP 400 is returned with the error messages, otherwise a HTTP 200 is returned with the assigned account ID.

Spring 3 provides first-class Ajax support with JSON as part of the Spring MVC module. This includes support for generating JSON responses and binding JSON requests using the Spring MVC @Controller programming model in conjunction with the Jackson JSON processor. In this article, I showed you how this support works. I hope you found this post useful, and look forward to hearing more of your experiences putting Spring 3 to work in your own applications!