The Java EE 5 Tutorial (PDF) - Oracle Software Downloads

ProgrammingTagsThat Accept Scripting Elements
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:
!
ProgrammingTagsThat Accept Scripting Elements
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Tags that accept scripting elements in attribute values or in the body cannot be programmed as
simple tags; they must be implemented as classic tags. The following sections describe the TLD
elements and JSP tag extension API specific to classic tag handlers. All other TLD elements are
the same as for simple tags.
TLD Elements
You specify the character of a classic tag’s body content using the body-content element:
empty | JSP | tagdependent
You must declare the body content of tags that do not have a body as empty. For tags that have a
body, there are two options. Body content containing custom and core tags, scripting elements,
and HTML text is categorized as JSP. All other types of body content (for example, SQL
statements passed to the query tag) are labeled tagdependent.
Tag Handlers
The classes and interfaces used to implement classic tag handlers are contained in the
javax.servlet.jsp.tagext package. Classic tag handlers implement either the Tag, the
IterationTag,ortheBodyTag interface. Interfaces can be used to take an existing Java object
and make it a tag handler. For newly created classic tag handlers, you can use the TagSupport
and BodyTagSupport classes as base classes. These classes and interfaces are contained in the
javax.servlet.jsp.tagext package.
The Java EE 5Tutorial • June 2010