JSP Standard Actions

JSP actions are special XML tags that control the behavior of the servlet engine. JSP actions allow you to insert a file dynamically, reuse external JavaBean components, forward the request to the other page and generate HTML for Java Applet Plugin.

jsp:include action

JSP include action allows you to include a file at runtime. The syntax of JSP include action is as follows:

<jsp:include page="Relative URL" flush="true" />
Code language: HTML, XML (xml)

In the page attribute, you insert a relative URL of a file which could be an HTML file or another JSP page. Unlike the include directive, the jsp include action insert a file at the time page is being requested.

jsp:useBean action

JSP useBean action lets you load a JavaBean component into the page and use it later. JSP useBean action allows you to reuse other Java classes. The syntax of JSP useBean action is as follows:

<jsp:useBean id="objectName" class="package.class" />
Code language: JavaScript (javascript)

By using the jsp:useBean action, you create a new object with the object nameobjectName of the class package.class. Later on, you can access the properties of this object by using either jsp:setProperty or jsp:getProperty. Let’s take a look at an example. First, we have a JavaBeans call Message:

public class Message {     private String text;     /**      * @return the text      */     public String getText() {         return text;     }     /**      * @param text the text to set      */     public void setText(String text) {         this.text = text;     } }
Code language: PHP (php)

Then we create a JSP page that uses the jsp:useBean action to access JavaBean Message inside that page.

<html>     <head>         <title>jsp:useBean Demo</title>     </head>     <body>         <jsp:useBean id="msg"                      class="com.jsptutorial.Message" />         <jsp:setProperty name="msg"                          property="text"                          value="JSP useBean Demo" />         <h1>         <jsp:getProperty name="msg"                          property="text" />         </h1>     </body> </html>
Code language: HTML, XML (xml)

We use jsp:setProperty to set the text property of the JavaBean Message and then we call jsp:getProperty to get that message and print it out. Here is the output screenshot:

jsp:forward Action

jsp:forward action allows you to forward a request to the other page. The syntax of the jsp:forward action is listed as below. There is one attribute called page which value is a page you want to forward the request to. You can specify the page statically or dynamically by using the expression.

<jsp:forward page="error.jsp" /> <jsp:forward page="<%= java-expression %>" />
Code language: HTML, XML (xml)

jsp:plugin Action

jsp:plugin action allows you to embedded Java Applet into a page. Suppose you have an applet which demonstrates the JSP page life cycle called com.jsp.jspapplet. Here is the way we use jsp:plugin action to embedded that applet into a page:

<html> <head> <title>jsp:plugin Demo</title> </head> <body> <jsp:plugin type="applet"             code="com.jsp.jspapplet"             codebase="."                 width="500"             height="400">     <jsp:fallback>         <p>Unable to use Java Plugin</p>     </jsp:fallback> </jsp:plugin> </body> </html>
Code language: HTML, XML (xml)