Document Information


Part I Introduction

1.  Overview

2.  Using the Tutorial Examples

Part II The Web Tier

3.  Getting Started with Web Applications

4.  Java Servlet Technology

5.  JavaServer Pages Technology

6.  JavaServer Pages Documents

7.  JavaServer Pages Standard Tag Library

8.  Custom Tags in JSP Pages

9.  Scripting in JSP Pages

The Example JSP Pages

Using Scripting

Disabling Scripting

JSP Declarations

Initializing and Finalizing a JSP Page

JSP Scriptlets

Programming Tags That Accept Scripting Elements

TLD Elements

Tag Handlers

How Is a Classic Tag Handler Invoked?

Tags with Bodies

Tag Handler Does Not Manipulate the Body

Tag Handler Manipulates the Body

Cooperating Tags

Tags That Define Variables

10.  JavaServer Faces Technology

11.  Using JavaServer Faces Technology in JSP Pages

12.  Developing with JavaServer Faces Technology

13.  Creating Custom UI Components

14.  Configuring JavaServer Faces Applications

15.  Internationalizing and Localizing Web Applications

Part III Web Services

16.  Building Web Services with JAX-WS

17.  Binding between XML Schema and Java Classes

18.  Streaming API for XML

19.  SOAP with Attachments API for Java

Part IV Enterprise Beans

20.  Enterprise Beans

21.  Getting Started with Enterprise Beans

22.  Session Bean Examples

23.  A Message-Driven Bean Example

Part V Persistence

24.  Introduction to the Java Persistence API

25.  Persistence in the Web Tier

26.  Persistence in the EJB Tier

27.  The Java Persistence Query Language

Part VI Services

28.  Introduction to Security in the Java EE Platform

29.  Securing Java EE Applications

30.  Securing Web Applications

31.  The Java Message Service API

32.  Java EE Examples Using the JMS API

33.  Transactions

34.  Resource Connections

35.  Connector Architecture

Part VII Case Studies

36.  The Coffee Break Application

37.  The Duke's Bank Application

Part VIII Appendixes

A.  Java Encoding Schemes

B.  About the Authors



JSP Expressions

A JSP expression is used to insert the value of a scripting language expression, converted into a string, into the data stream returned to the client. When the scripting language is the Java programming language, an expression is transformed into a statement that converts the value of the expression into a String object and inserts it into the implicit out object.

The syntax for an expression is as follows:

<%= scripting-language-expression %>

Note that a semicolon is not allowed within a JSP expression, even if the same expression has a semicolon when you use it within a scriptlet.

In the web service version of the hello1 application, response.jsp contains the following scriptlet, which gets the proxy that implements the service endpoint interface. It then invokes the sayHello method on the proxy, passing the user name retrieved from a request parameter:

    String resp = null;
    try {
        Hello hello = new HelloService().getHelloPort();
        resp = hello.sayHello(request.getParameter("username"));
    } catch (Exception ex) {
        resp = ex.toString();

A scripting expression is then used to insert the value of resp into the output stream:

<h2><font color="black"><%= resp %>!</font></h2>