JavaServer Pages in Software Printer qr bidimensional barcode in Software JavaServer Pages

2. use software qr codes printer toadd qr-codes on software QR Codes Summary. This chapter cove red how to develop, configure, package, and deploy servlets. We also covered how to process HTML form information by accessing the HTTP request object. Additionally, forwarding HTTP requests from one servlet to another was covered, as well as redirecting the HTTP response to a different server.

We also discussed how to persist objects in memory across requests by attaching them to the servlet context and the HTTP session. Finally, we covered all the major new features of Servlet 3.0, including configuring web applications via annotations, pluggability through web-fragment.

xml, programmatic servlet configuration, and asynchronous processing.. [ 79 ]. JavaServer Pages In the previous c Denso QR Bar Code for None hapter, we saw how to develop Java servlets. Servlets are great for handling form input, but servlet code that outputs HTML markup to the browser tends to be cumbersome to write, read, and debug. A better way to send output to the browser is through JavaServer Pages (JSPs).

The following topics will be covered in this chapter: Developing our first JSP Implicit JSP objects JSPs and JavaBeans Reusing JSP content Writing custom tags. Introduction to JavaServer Pages In the early days Software qrcode , servlets were the only API available to develop server-side web applications in Java. Servlets had a number of advantages over CGI scripts, which were (and to some extent, still are) prevalent in those days. Some of the advantages of servlets over CGI scripts included increased performance and enhanced security.

However, servlets also had one major disadvantage. As the HTML code to be rendered in the browser needed to be embedded in Java code, most servlet code was very hard to maintain. To overcome this limitation, Java Server Pages (JSP) technology was created.

JSPs use a combination of static HTML content and dynamic content to generate web pages. As the static content is separate from the dynamic content, JSP pages are a lot easier to maintain than servlets that generate HTML output..

JavaServer Pages In most modern ap QR Code for None plications using JSPs, servlets are still used. However, they typically assume the role of a controller in the Model-View-Controller (MVC) design pattern, with JSPs assuming the role of a view. As controller servlets have no user interface, we don"t run into the issue of having HTML markup inside Java code.

In this chapter, we will cover how to develop server-side web applications using JavaServer Pages technology.. Developing our first JSP JSPs are basicall qr bidimensional barcode for None y pages containing both static HTML markup and dynamic content. Dynamic content can be generated by using snippets of Java code called scriptlets or by using standard or custom JSP tags. Let"s look at a very simple JSP code that displays the current server time in the browser:.

<%@ page langu age="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ page import="java.util.Date" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.

01 Transitional//EN" "

dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Server Date And Time</title> </head> <body> <p>Server date and time: <% out.print(new Date()); %> </p> </body> </html>. To deploy this JS QR Code 2d barcode for None P, all that needs to be done is to put it in a WAR file. Like we mentioned before, the easiest way to deploy the WAR file is to copy it to [glassfish installation directory]/glassfish/domains/domain1/autodeploy..

[ 82 ]. 3 . Quickly deploying simple JSPs Simple JSPs can be quickly deployed without having to package them in a WAR file by copying them to [glassfish installation directory]/glassfish/domains/domain1/ docroot/, and previewed in the browser by pointing them to http://localhost:8080/jspname.jsp..

After a successfu Software qr bidimensional barcode l deployment, pointing the browser to http://localhost:8080/ firstjsp/first.jsp should result in a page like the following:. The Server date a nd time: string came from the static text immediately following the <p> tag in the JSP page. The actual date and time displayed is the server"s date and time. The value came from the output of the code between the <% and %> delimiters.

We can place any valid Java code between these two delimiters. Code inside these delimiters is known as a scriptlet. The scriptlet in the previous JSP makes use of the out implicit object.

JSP implicit objects are objects that can be readily used in any JSP; no need to declare or initialize them. The out implicit object is an instance of javax.servlet.

jsp.JspWriter. It can be thought of as an equivalent of calling the HttpServletResponse.

getWriter() method. The first two lines in the previous JSP are JSP page directives. A JSP page directive defines attributes that apply to the entire JSP page.

A JSP page directive can have several attributes. In the previous example, the first page directive sets the language, contentType, charset, and PageEncoding attributes. The second one adds an import statement to the page.

As can be seen in the example, JSP page directive attributes can be combined in a single directive, or a separate page directive can be used for each attribute.. [ 83 ].
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