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What Is a JSP Page?

AJSP page is a text document that contains two types of text: staticdata, which can be expressed in any text-based format (such asHTML,SVG,WML, andXML), and JSP elements, which construct dynamic content.

The recommended file extension for the source file of a JSP pageis.jsp. The page can be composed of a top file thatincludes other files that contain either a complete JSP page or a fragmentof a JSP page. The recommended extension for the source file of afragment of a JSP page is.jspf.

The JSP elements in a JSP page can be expressed in twosyntaxes, standard and XML, though any given file can use only one syntax.A JSP page in XML syntax is an XML document and can bemanipulated by tools and APIs for XML documents. This chapter and ChaptersChapter 7, JavaServer Pages Standard Tag LibrarythroughChapter 9, Scripting in JSP Pages document only the standard syntax. The XML syntax is covered inChapter 6, JavaServer Pages Documents.

A Simple JSP Page Example

The web page inFigure 5-1 is a form that allows you to selecta locale and displays the date in a manner appropriate to the locale.

Figure 5-1 Localized Date Form

Screen capture of localized date form. Locale drop-down shows Lithuanian. Get Date button displays the date,

The source code for this example is in thetut-install/javaeetutorial5/examples/web/date/ directory. TheJSP page,index.jsp, appears below; it is a typical mixture of static HTMLmarkup and JSP elements. If you have developed web pages, you are probablyfamiliar with the HTML document structure statements (<head>,<body>, and so on) and theHTML statements that create a form (<form>) and a menu (<select>).

The lines in bold in the example code contain the following typesof JSP constructs:

A page directive (<%@page ... %>) sets the content type returned by the page.
Tag library directives (<%@taglib ... %>) import custom tag libraries.
jsp:useBean is a standard element that creates an object containing a collection of locales and initializes an identifier that points to that object.
JSP expression language expressions (${ }) retrieve the value of object properties. The values are used to set custom tag attribute values and create dynamic content.
Custom tags (seeChapter 8, Custom Tags in JSP Pages) set a variable (c:set), iterate over a collection of locale names (c:forEach), and conditionally insert HTML text into the response (c:if,c:choose,c:when,c:otherwise).
jsp:setProperty is another standard element that sets the value of an object property.
A function (f:equals) tests the equality of an attribute and the current item of a collection. (A built-in== operator is usually used to test equality.)

Here is the JSP page:

<%@page contentType="text/html; charset=UTF-8" %><%@taglib uri="http://java.sun.com/jsp/jstl/core"         prefix="c" %><%@taglib uri="/functions" prefix="f" %><html><head><title>Localized Dates</title></head><body bgcolor="white"><jsp:useBean scope="application"   /><form name="localeForm" action="index.jsp" method="post"><c:set var="selectedLocaleString" value="${param.locale}" /><c:set var="selectedFlag"     value="${!empty selectedLocaleString}" /><b>Locale:</b><select name=locale><c:forEach var="localeString" items="${locales.localeNames}" ><c:choose>    <c:when test="${selectedFlag}">        <c:choose>            <c:when                 test="${f:equals(selectedLocaleString, localeString)}" >                <option selected>${localeString}</option>            </c:when>            <c:otherwise>                <option>${localeString}</option>            </c:otherwise>        </c:choose>    </c:when>    <c:otherwise>        <option>${localeString}</option>    </c:otherwise></c:choose></c:forEach></select><input type="submit" name="Submit" value="Get Date"></form><c:if test="${selectedFlag}" >    <jsp:setProperty name="locales"        property="selectedLocaleString"        value="${selectedLocaleString}" />    <jsp:useBean/>    <jsp:setProperty name="date" property="locale"        value="${locales.selectedLocale}"/>    <b>Date: </b>${date.date}</c:if></body></html>

To deploy thedate application with NetBeans IDE, follow these steps:

Start the Application Server.
In NetBeans IDE, select File→Open Project.

In the Open Project dialog, navigate to:

tut-install/javaeetutorial5/examples/web/

Select thedate folder.
Select the Open as Main Project check box.
Click Open Project.
In the Projects tab, right-click thedate project, and select Undeploy and Deploy.

To deploy thedate application with the Ant tool, follow these steps:

In a terminal window, go totut-install/javaeetutorial5/examples/web/date/.
Typeant. This command will spawn any necessary compilations, copy files to thetut-install/javaeetutorial5/examples/web/date/build/ directory, and create a WAR file.
Start the Application Server.
Typeant deploy.

To run the example, do the following:

Set the character encoding in your browser to UTF-8.
Open your browser tohttp://localhost:8080/date.
You will see a combo box whose entries are locales. Select a locale and click Get Date. You will see the date expressed in a manner appropriate for that locale.

Some of the characters might not display properly if you don’t have theappropriate language files installed on your machine. Consult the user guide or onlinehelp for your operating system to determine how you can install these languagefiles.

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The Java EE 5 Tutorial

What Is a JSP Page?

A Simple JSP Page Example