JSP standard actions

1.What are the JSP standard actions?

• The JSP standard actions affect the overall runtime behavior of a JSP page and also the response sent back to the client.
• They can be used to include a file at the request time, to find or instantiate a JavaBean, to forward a request to a new page, to generate a browser-specific code, etc.
• Ex: include, forward, useBean,etc. object

2.What are the standard actions available in JSP?

The standard actions available in JSP are as follows:

• <jsp:include>: It includes a response from a servlet or a JSP page into the current page. It differs from an include directive in that it includes a resource at request processing time, whereas the include directive includes a resource at translation time.
• <jsp:forward>: It forwards a response from a servlet or a JSP page to another page.
• <jsp:useBean>: It makes a JavaBean available to a page and instantiates the bean.
• <jsp:setProperty>: It sets the properties for a JavaBean.
• <jsp:getProperty>: It gets the value of a property from a JavaBean component and adds it to the response.
• <jsp:param>: It is used in conjunction with <jsp:forward>;, <jsp:, or plugin>; to add a parameter to a request. These parameters are provided using the name-value pairs.
• <jsp:plugin>: It is used to include a Java applet or a JavaBean in the current JSP page.

3.What is the <jsp:useBean> standard action?

The <jsp:useBean> standard action is used to locate an existing JavaBean or to create a JavaBean if it does not exist. It has attributes to identify the object instance, to specify the lifetime of the bean, and to specify the fully qualified classpath and type.

4.What are the scopes available in <jsp:useBean>?

The scopes available in <jsp:useBean> are as follows:

• page scope:: It specifies that the object will be available for the entire JSP page but not outside the page.
• request scope: It specifies that the object will be associated with a particular request and exist as long as the request exists.
• application scope: It specifies that the object will be available throughout the entire Web application but not outside the application.
• session scope: It specifies that the object will be available throughout the session with a particular client.

5.What is the <jsp:forward> standard action?

• The <jsp:forward> standard action forwards a response from a servlet or a JSP page to another page.
• The execution of the current page is stopped and control is transferred to the forwarded page.
• The syntax of the <jsp:forward> standard action is :  
• <jsp:forward page="/targetPage" />
• Here, targetPage can be a JSP page, an HTML page, or a servlet within the same context.
• If anything is written to the output stream that is not buffered before <jsp:forward>, an IllegalStateException will be thrown.

Note : Whenever we intend to use <jsp:forward> or <jsp:include> in a page, buffering should be enabled. By default buffer is enabled.

6.What is the <jsp:include> standard action?

The <jsp:include> standard action enables the current JSP page to include a static or a dynamic resource at runtime. In contrast to the include directive, the include action is used for resources that change frequently. The resource to be included must be in the same context.The syntax of the <jsp:include> standard action is as follows:
<jsp:include page="targetPage" flush="true"/> 
Here, targetPage is the page to be included in the current JSP.