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Including an Applet

You can include an applet or JavaBeans component in a JSP page by using the jsp:plugin element. This element generates HTML that contains the appropriate client-browser-dependent constructs (<object> or <embed>) that will result in the download of the Java Plug-in software (if required) and client-side component and subsequent execution of any client-side component. The syntax for the jsp:plugin element is as follows:

<jsp:plugin 
   type="bean|applet" 
   code="objectCode" 
   codebase="objectCodebase" 
   { align="alignment" } 
   { archive="archiveList" } 
   { height="height" } 
   { hspace="hspace" } 
   { jreversion="jreversion" } 
   { name="componentName" } 
   { vspace="vspace" } 
   { width="width" } 
   { nspluginurl="url" } 
   { iepluginurl="url" } > 
   { <jsp:params> 
      { <jsp:param name="paramName" value="paramValue" /> }+
   </jsp:params> } 
   { <jsp:fallback> arbitrary_text </jsp:fallback> } 
</jsp:plugin>
 

The jsp:plugin tag is replaced by either an <object> or <embed> tag as appropriate for the requesting client. The attributes of the jsp:plugin tag provide configuration data for the presentation of the element as well as the version of the plug-in required. The nspluginurl and iepluginurl attributes specify the URL where the plug-in can be downloaded.

The jsp:param elements specify parameters to the applet or JavaBeans component. The jsp:fallback element indicates the content to be used by the client browser if the plug-in cannot be started (either because <object> or <embed> is not supported by the client or because of some other problem).

If the plug-in can start but the applet or JavaBeans component cannot be found or started, a plug-in-specific message will be presented to the user, most likely a pop-up window reporting a ClassNotFoundException.

The Duke's Bookstore page banner.jsp that creates the banner displays a dynamic digital clock generated by DigitalClock (Figure 11-3).

The jsp:plugin element used to download the applet follows:

<jsp:plugin 
   type="applet" 
   code="DigitalClock.class" 
   codebase="/bookstore2" 
   jreversion="1.3" 
   align="center" height="25" width="300"
   nspluginurl="http://java.sun.com/products/plugin/1.3.0_01
      /plugin-install.html" 
   iepluginurl="http://java.sun.com/products/plugin/1.3.0_01
      /jinstall-130_01-win32.cab#Version=1,3,0,1" >
   <jsp:params>
      <jsp:param name="language"
         value="<%=request.getLocale().getLanguage()%>" />
      <jsp:param name="country"
         value="<%=request.getLocale().getCountry()%>" />
      <jsp:param name="bgcolor" value="FFFFFF" />
      <jsp:param name="fgcolor" value="CC0066" />
   </jsp:params>
      <jsp:fallback>
      <p>Unable to start plugin.</p>
   </jsp:fallback>
</jsp:plugin>
 

Figure 11-3 Duke's Bookstore with Applet

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