Spring 3 formatter API provides a facility to bind an Annotation to a org.springframework.format.Formatter implementation. When creating a custom Formatter, we can define a corresponding annotation and bind that annotation to our formatter.
In this example we are going to define our own formatter annotation.
To bind an Annotation to a formatter, we have to implement AnnotationFormatterFactory
package org.springframework.format;
public interface AnnotationFormatterFactory<A extends Annotation> {
Set<Class<?>> getFieldTypes();
Printer<?> getPrinter(A annotation, Class<?> fieldType);
Parser<?> getParser(A annotation, Class<?> fieldType);
}
In our last example we created a new formatter AddressFormatter by extending Formatter interface. Here we are going to bind the same formatter to a new annotation @AddressFormat. Doing so will enable us to declare formatting on field level.
Creating Backing object classes
public class Customer {
private Long id;
private String name;
private Address address;
//getters and setters
}
public class Address {
private String street;
private String city;
private String county;
private String zipCode;
//getters and setters
}
Creating our Formatter
import org.springframework.format.Formatter;
import java.text.ParseException;
import java.util.Locale;
public class AddressFormatter implements Formatter<Address> {
private Style style = Style.FULL;
public void setStyle (Style style) {
this.style = style;
}
@Override
public Address parse (String text, Locale locale) throws ParseException {
.....
return address;
}
@Override
public String print (Address a, Locale l) {
...
return addressString;
}
public enum Style {
FULL,
REGION
}
}
Creating Annotation
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface AddressFormat {
AddressFormatter.Style style () default AddressFormatter.Style.FULL;
}
Using annotation in our backing object class
package com.logicbig.example;
public class Customer {
private Long id;
private String name;
@AddressFormat(style = AddressFormatter.Style.FULL)
private Address address;
//getters and setters
}
Binding our Annotation by implementing AnnotationFormatterFactory
import org.springframework.format.AnnotationFormatterFactory;
import org.springframework.format.Parser;
import org.springframework.format.Printer;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
public class AddressFormatAnnotationFormatterFactory implements
AnnotationFormatterFactory<AddressFormat> {
@Override
public Set<Class<?>> getFieldTypes () {
return new HashSet<>(Arrays.asList(Address.class));
}
@Override
public Printer<?> getPrinter (AddressFormat annotation, Class<?> fieldType) {
return getAddressFormatter(annotation, fieldType);
}
@Override
public Parser<?> getParser (AddressFormat annotation, Class<?> fieldType) {
return getAddressFormatter(annotation, fieldType);
}
private AddressFormatter getAddressFormatter (AddressFormat annotation,
Class<?> fieldType) {
AddressFormatter formatter = new AddressFormatter();
formatter.setStyle(annotation.style());
return formatter;
}
}
Registering The AnnotationFormatterFactory
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@EnableWebMvc
@Configuration
@Import(MyViewConfig.class)
public class MyWebConfig extends WebMvcConfigurerAdapter {
@Override
public void addFormatters (FormatterRegistry registry) {
AddressFormatAnnotationFormatterFactory factory = new
AddressFormatAnnotationFormatterFactory();
registry.addFormatterForFieldAnnotation(factory);
}
.....
}
Creating Controller
@Controller
@RequestMapping("/customers")
public class CustomerController {
@Autowired
private CustomerDataService customerDataService;
@RequestMapping(method = RequestMethod.GET)
private String handleRequest (Model model) {
model.addAttribute("customerList", customerDataService.getAllUsers());
return "customers";
}
}
customer.jsp
<%@ 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"%>
<%@taglib uri="http://www.springframework.org/tags" prefix="spring" %>
<html>
<body>
<h3>Customer List </h3>
<table style="width:100%">
<c:forEach var="customer" items="${customerList}" varStatus="status">
<tr>
<td>
<spring:eval expression="customer.id" />
</td>
<td>
<spring:eval expression="customer.name" />
</td>
<td>
<spring:eval expression="customer.address" />
</td>
</tr>
</c:forEach>
</table>
</body>
</html>
Example Project
Run the web application by using embedded tomcat:
mvn clean install tomcat7:run-war
Dependencies and Technologies Used: - Spring Web MVC 4.2.4.RELEASE: Spring Web MVC.
- Spring TestContext Framework 4.2.4.RELEASE: Spring TestContext Framework.
- Java Servlet API 3.0.1
- javax.servlet:jstl 1.2
- JUnit 4.12: JUnit is a unit testing framework for Java, created by Erich Gamma and Kent Beck.
- DataFactory 0.8: Library to generate data for testing.
- JDK 1.8
- Maven 3.0.4
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