Converters
in JSF :-
In
a web application the data entered in a form is always of String data
type.
Consider
a web page form having first name,last name and Age.Here names are
of String type and Age is Number data type. But when the data is
sent from form to server every filed is String type.
How
to convert Age field data to integer type before assigning it to
managed bean/backing bean? We can explicitly convert it by using
Integer.parseInt() etc.Doing this way is tedious and not reusable.
Does
JSF provide any mechanism to handle this?
Yes
JSF provides a mechanism to convert these String types into
respective data type.
- For implicit data types JSF provides implicit conversion
- For non primitive types we need to convert explicitly by using Standard Converters( for converting String to Date etc.)or by creating custom converters
First
we will see different standard converters.
|
SNO
|
|
MAIL
|
|---|---|---|
|
1
|
ByteConverter
|
Converts
input String value to java.lang.Byte
|
|
2
|
BooleanConverter
|
Converts
input String value to java.lang.Boolean
|
|
3
|
BigDecimalConverter
|
Converts
input String value Java.lang.BigDecimal
|
|
4
|
BigIntegerConveter
|
Converts
input String value to java.lang.BigInteger
|
|
5
|
CharacterConverter
|
Converts
input String value to java.lang.Character
|
|
6
|
DateTimeConverter
|
Converts
input String value to java.util.Date
|
|
7
|
NumberConverter
|
Converts
input String value to java.lang.Number
|
|
8
|
IntegerConverter
|
Converts
input String value to java.lang.Integer
|
|
9
|
FloatConverter
|
Converts
input String value to java.lang.Float
|
Similarly
we have EnumConverter,ShortConverter etc.
There
are three different ways to use this Standard converters.
- Using Converter attribute in input tags
- Using nested sub-tag <f:converter>
- Using standard converters like <f:convertDateTime>,<f:convertNumber> etc.
Lets
see each of the above with examples.
1.Using
Converter attribute in input tags :-
- inputText,inputSecret,inputHidden,outputText are supported tags
- Lets takes an example of entering date and using converter attribute<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@
taglib prefix="f"
uri="http://java.sun.com/jsf/core"%>
<%@
taglib prefix="h"
uri="http://java.sun.com/jsf/html"%>
<!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>Date</title>
</head>
<body>
<f:view>
<h:form>
Date
<h:inputText
id="myDate"
value="#{loginBean.date}"
converter="javax.faces.DateTime">
</h:inputText>
<h:commandButton
value="submit"
></h:commandButton>
<h:message
for="myDate"></h:message>
</h:form>
</f:view>
</body>
</html>
- Here we have used DateTime converter attribute in input text,the value entered should be like Aug 5, 2013--> mmm d, yyyy. If we enter a value with different value it will throw error it is displayed by using <h:message> tag
2.Using
nested sub-tag <f:converter>
:-
<h:inputText
id="myDate"
value="#{loginBean.date}">
<f:converter
converterId="javax.faces.DateTime"
/>
</h:inputText>
Here
we have used converter tag inside inputText tag
3.Using
standard converters :-
we
will use <f:convertdateTime> tag
<h:inputText
id="myDate"
value="#{loginBean.date}">
<f:convertDateTime
type="date"
dateStyle="short"
/>
</h:inputText>
There
are different types of dateStyles like short,full etc.
Short
type will expect date as mm/dd/yyyy or mm/dd/yy .
Long
type will expect date as August
5, 2013
etc, this is generally used for outputText tag.
We
can change/add the behavior of this converters by developing custom
converters.
This
will be discussed in my next post.
Happy
Learning
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me @ sudheer@javarecent.com
or admin@java-recent.com
