How to create JSP error page to handle exceptions?

In this example you will learn how to handle exceptions in JSP page. JSP have a build-in mechanism for error handling which is a special page that can be used to handle every errors in the web application. To define a page as an error page we use the page directive and enable the isErrorPage attribute by setting the value to true.

Here is an example of a JSP error page:

We have define the error page. The next steps is how to tell other JSP pages to use the error page to handle errors when uncaught exception occurred. To do this we again use the page directive. Set the errorPage attribute of this directive to point to the error page. For instance in the example below we set it to errorPage.jsp.

If we try to access the errorTest.jsp as shown in the snippet below. It will throw an exception because we try to convert an invalid string into a number. Because we are not handling the error in the page the error page will comes up and show the exception messages.

How to include page dynamically in JSP page?

In this example we are going to learn how to use <jsp:include> action. This action can be use to include resource dynamically to our JSP pages. For example the resource can be another JSP page, a servlet or event a static html pages. But to make it enable to be processed as a JSP page, such as accepting parameters, we must use the .jsp as the file extension. If we use other extension such as .jspf, it will processed as a static page.

The other things to note is that using the <jsp:include> action will process the page inclusion at the request time. This is why we can pass parameters to the included page using the <jsp:param>. The value can be read by obtaining the parameter from the request object or using expression language variable param.

But if we use the <%@ include %> directive the inclusion of the page happen when it translated into a Servlet. See the following example about the <%@ include %> directive: How do I include a page fragment into JSP?

Below is the content of our footer.jsp page. In this page we display the footer information with a parameter read from the request object.

This example will give you the following result in the browser:

JSP Include Action

JSP Include Action

How do I forward request to another page in JSP?

To forward a request from one page to another JSP page we can use the <jsp:forward> action. This action has a page attribute where we can specify the target page of the forward action. If we want to pass parameter to another page we can include a <jsp:param> in the forward action. But make sure that the forward page is a JSP page to enable the parameters to be processed.

And here is how to read the parameters in the message.jsp.

 

JSP Forward Demo

JSP Forward Demo

When you access the jspForward.jsp page in the web browser what you will see is the content of the message.jsp page. This is because the <jsp:forward> action forward your request to the message.jsp before returning the response back to the browser for display.

How to set and get properties of a bean in JSP?

In this example you will learn how to set and get the value of Java object properties that you define in a JSP pages. For this example, let’s first start by creating a variable that we named customer, that will have a type of Customer class. To create this variable we use the <jsp:useBean> action.

After we create the customer variable we can set the property value of the customer bean using the <jsp:setProperty> action. And to get the property value of the customer bean we use the <jsp:getProperty> action.

The name attribute in the setProperty and getProperty action refer to our customer bean. The property attribute tells which property we are going to set or get. To set the value of a property we use the value attribute.

And here is the code for our Customer bean. This bean contains property such as the id, firstName, lastName and address.

We we access the JSP page we will see the following output:

JSP Bean Property Demo

JSP Bean Property Demo