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)
