Spring web mvc: property editors: customize properties binding

In this post, you are going to learn,

a.   What are property editors

b.   Property editors available in spring

c.   How to map text of type 'yyyy/mm/dd' to java.util.Date

d.   How to bind the Date of different format?

What are property editors?

Spring provides many property editors to customize the properties binding.

If you use @ModelAtribute annotation on method argument, spring binds all the request parameters to a java model object. But if you want any customizations in properties binding, you can achieve by using property editors.

For example, If the request parameter value is of format 'yyyy/mm/dd', then spring binds this value to java.util.Date. But if you want to bind parameter value of type 'yyyy@@mm@@dd' to kava.util.Date type, you should use property editors.

Property editors available in spring

Below table summarizes different property editors available in spring framework.

Property Editor	Description
ByteArrayPropertyEditor	Editor for byte arrays.
CharacterEditor	Editor for a Character, to populate a property of type Character or char from a String value.
CharArrayPropertyEditor	Editor for char arrays.
CharsetEditor	Editor for java.nio.charset.Charset, translating charset String representations into Charset objects and back.
ClassArrayEditor	Property editor for an array of Classes, to enable the direct population of a Class[] property without having to use a String class name property as bridge.
ClassEditor	Property editor for java.lang.Class, to enable the direct population of a Class property without recourse to having to use a String class name property as bridge.
CurrencyEditor	Editor for java.util.Currency, translating currency codes into Currency objects.
CustomBooleanEditor	Property editor for Boolean/boolean properties.
CustomCollectionEditor	Property editor for Collections, converting any source Collection to a given target Collection type.
CustomDateEditor	Property editor for java.util.Date, supporting a custom java.text.DateFormat.
CustomMapEditor	Property editor for Maps, converting any source Map to a given target Map type.
CustomNumberEditor	Property editor for any Number subclass such as Short, Integer, Long, BigInteger, Float, Double, BigDecimal.
FileEditor	Editor for java.io.File, to directly populate a File property from a Spring resource location.
InputSourceEditor	Editor for org.xml.sax.InputSource, converting from a Spring resource location String to a SAX InputSource object.
InputStreamEditor	One-way PropertyEditor which can convert from a text String to a java.io.InputStream, interpreting the given String as a Spring resource location (e.g.
LocaleEditor	Editor for java.util.Locale, to directly populate a Locale property.
PathEditor	Editor for java.nio.file.Path, to directly populate a Path property instead of using a String property as bridge.
PatternEditor	Editor for java.util.regex.Pattern, to directly populate a Pattern property.
PropertiesEditor	Custom PropertyEditor for Properties objects.
ReaderEditor	One-way PropertyEditor which can convert from a text String to a java.io.Reader, interpreting the given String as a Spring resource location (e.g.
ResourceBundleEditor	PropertyEditor implementation for standard JDK ResourceBundles.
StringArrayPropertyEditor	Custom PropertyEditor for String arrays.
StringTrimmerEditor	Property editor that trims Strings.
TimeZoneEditor	Editor for java.util.TimeZone, translating timezone IDs into TimeZone objects.
URIEditor	Editor for java.net.URI, to directly populate a URI property instead of using a String property as bridge.
URLEditor	Editor for java.net.URL, to directly populate a URL property instead of using a String property as bridge.
UUIDEditor	Editor for java.util.UUID, translating UUID String representations into UUID objects and back.
ZoneIdEditor	Editor for java.time.ZoneId, translating zone ID Strings into ZoneId objects.

How to map text of type 'yyyy/mm/dd' to java.util.Date?

I am going to develop a student registration form. Student must provide below information to register himself.

Information	Type
userName	String
age	int
hobbies	Collection
dateOfBirth	java.util.Date

public class Student {

         private String userName;

         private int age;

         private List<String> hobbies;

         private Date dateOfBirth;

         .....

         .....

}

There is nothing special about date mapping. Use the @ModelAttribute annotation on method argument of Student object, spring takes care of data binding for you.

@RequestMapping("/registerMe")

public ModelAndView getHelloMessage(@ModelAttribute("studentInfo") Student student, BindingResult bindingResult) {

         .....

         .....

}      

Find the below working application.

HelloWorldController.java

package com.sample.myApp.controllers;

import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.sample.myApp.model.Student;

@Controller
public class HelloWorldController {

 @RequestMapping("/registration")
 public String getRegistrationpage() {
  return "registration";
 }

 @RequestMapping("/registerMe")
 public ModelAndView getHelloMessage(@ModelAttribute("studentInfo") Student student, BindingResult bindingResult) {
  if (bindingResult.hasErrors()) {
   ModelAndView modelAndView = new ModelAndView("registration");
   return modelAndView;
  }

  ModelAndView modelAndView = new ModelAndView("welcome");

  modelAndView.addObject("message", "Dear User, your details are registered");

  return modelAndView;
 }

}

Student.java

package com.sample.myApp.model;

import java.util.Date;
import java.util.List;

public class Student {
 private String userName;
 private int age;
 private List<String> hobbies;
 private Date dateOfBirth;

 public Date getDateOfBirth() {
  return dateOfBirth;
 }

 public void setDateOfBirth(Date dateOfBirth) {
  this.dateOfBirth = dateOfBirth;
 }

 public String getUserName() {
  return userName;
 }

 public void setUserName(String userName) {
  this.userName = userName;
 }

 public int getAge() {
  return age;
 }

 public void setAge(int age) {
  this.age = age;
 }

 public List<String> getHobbies() {
  return hobbies;
 }

 public void setHobbies(List<String> hobbies) {
  this.hobbies = hobbies;
 }

}

Create registration.jsp, hello.jsp files under WEB-INF/jsp folder.

registration.jsp

<%@taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<html>
<head>
<title>User Information Page</title>
</head>

<body>
 <h2 style="color:red;"><form:errors path="studentInfo.*" /></h2>

 <form method="post" action="/springdemo/registerMe" id="f1">
  <table>
   <tr>
    <td>User Name :</td>
    <td><input type="text" name="userName" value="" /></td>
   </tr>
   <tr>
    <td>Age :</td>
    <td><input type="text" name="age" value="" /></td>
   </tr>
   <tr>
    <td>Hobbies :</td>
    <td><select multiple name="hobbies">
      <option value="cricket">Cricket</option>
      <option value="chess">Chess</option>
      <option value="football">Football</option>
      <option value="tennis">Tennis</option>
    </select></td>
   </tr>
   
   <tr>
    <td>Date Of Birth</td>
    <td><input type="text" name="dateOfBirth" value="" /></td>
   </tr>
   <tr>
    <td><input type="submit" name="submit" value="submit"
     style="font-size: 18px;" /></td>
   </tr>
  </table>
 </form>

</body>
</html>

welcome.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Hello World Spring Web MVC</title>
</head>
<body>
 <h1>${message}</h1>

 <h3>
  User Name : ${studentInfo.userName} <br /> 
  Age : ${studentInfo.age} <br />
  Hobbies: ${studentInfo.hobbies} <br />
  Date Of Birth: ${studentInfo.dateOfBirth}
 </h3>
</body>
</html>

Create web.xml, HelloWorld-servlet.xml files under WEB-INF folder.

web.xml

<web-app id="WebApp_ID" version="2.4"
 xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

 <display-name>Spring MVC Hello WorldApplication</display-name>

 <servlet>
  <servlet-name>HelloWorld</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>

 <servlet-mapping>
  <servlet-name>HelloWorld</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>

</web-app>

HelloWorld-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:context="http://www.springframework.org/schema/context"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="
   http://www.springframework.org/schema/beans     
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/context 
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">

 <context:component-scan
  base-package="com.sample.myApp" />

 <bean
  class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <property name="prefix" value="/WEB-INF/jsp/" />
  <property name="suffix" value=".jsp" />
 </bean>

</beans>

Create index.jsp file under webapp folder.

index.jsp

<%@taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<html>
<head>
<title>Welcome Page</title>
</head>

<body>
 <h3>Dear Student, click on below button to register yourself</h3>
 <form method="post" action="/springdemo/registration" id="f1">
  <input type="submit" name="submit" value="submit"
   style="font-size: 18px;" />
 </form>
</body>
</html>

Project structure looks like below.

Run the application on server. You can able to get below kind of screen.

Click on submit button, it navigates you to the registration page.

Fill the registration form, fill the date in ‘YYYY/MM/DD’ format. Click on submit button.

You can able to see successful message like below.

Now go back to the registration page again and enter the date in ‘YYYY@@MM@@DD’ format.

Click on submit button, you can able to see below kind of data bind error.

It is because, spring doesn’t know how to bind the string of format ‘YYYY@@MM@@DD’ to date type.

How to bind the Date of different format?

By using custom property editors, we can customize the data binding process.

For example, below method customize the date format. I am using spring CustomDateEditor class to support custom date format.

@InitBinder

public void customizeBinding(WebDataBinder dataBinder) {

         SimpleDateFormat dateFormat = new SimpleDateFormat("YYYY@@MM@@DD");

         dataBinder.registerCustomEditor(Date.class, "dateOfBirth", new CustomDateEditor(dateFormat, false));

}

Update HelloWorldController class like below.

HelloWorldController.java

package com.sample.myApp.controllers;

import java.sql.Date;
import java.text.SimpleDateFormat;

import org.springframework.beans.propertyeditors.CustomDateEditor;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.sample.myApp.model.Student;

@Controller
public class HelloWorldController {

 @InitBinder
 public void customizeBinding(WebDataBinder dataBinder) {
  SimpleDateFormat dateFormat = new SimpleDateFormat("YYYY@@MM@@DD");
  dataBinder.registerCustomEditor(Date.class, "dateOfBirth", new CustomDateEditor(dateFormat, false));
 }

 @RequestMapping("/registration")
 public String getRegistrationpage() {
  return "registration";
 }

 @RequestMapping("/registerMe")
 public ModelAndView getHelloMessage(@ModelAttribute("studentInfo") Student student, BindingResult bindingResult) {
  if (bindingResult.hasErrors()) {
   ModelAndView modelAndView = new ModelAndView("registration");
   return modelAndView;
  }

  ModelAndView modelAndView = new ModelAndView("welcome");

  modelAndView.addObject("message", "Dear User, your details are registered");

  return modelAndView;
 }

}

Re deploy the application on server. Now enter the date in ‘YYYY@@MM@@DD’ format.

Click on submit button. You can able to see successful message.

In my next post, I am going to explain about property editors.

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