Also, note that the about: However, due to legacy constraints, it has gained another very important purpose: HTML5 defines three modes:
The advantages of JSP are: Separation of static and dynamic contents: JSP enables the separation of static contents from dynamic contents.
The dynamic contents are generated via programming logic and inserted into the static template. This greatly simplifies the creation and maintenance of web contents. Reuse of components and tag libraries: The dynamic contents can be provided by reusable components such as JavaBean, Enterprise JavaBean EJB and tag libraries - you do not have to re-inventing the wheels.
However, it is important to note that servlets and JSPs are complementary technologies, NOT replacement of each other.
Servlet can be viewed as "HTML inside Java", which is better for implementing business logic - as it is Java dominant.
JSPs are often used for the View Vwhich mainly deals with presentation. We shall use the webapp called "hello" that we have created in our earlier exercise. From your browser, choose the "View Source" option to check the response message. It should be either of the followings depending on the random number generated.
Check out the generated servlet for "first. The relevant part of the generated servlet is extracted as follows with some simplifications: Hence, the expression will be evaluated, and the result of the evaluation written out as part of the response message.
Subsequent accesses to the same JSP will be much faster, because they will be re-directed to the converted and compiled servlet directly no JSP-to-servlet conversion and servlet compilation needed againunless the JSP has been modified.
Revisit Java Servlets A typical Java servlet as shown below contains three kinds of methods: The service methods takes two arguments: A PrintWriter called out is created for writing out the response to the network. Any change to the web page's presentation such as background color and font size requires re-coding and re-compilation of servlet program.
No "action" attribute is specified, the default "action" is the current page i. The JSP scriptlet checks if the query parameter "author" exists to decide whether to dynamically generate the enclosed codes.
The values are echoed back using an unordered list. This expression will be placed inside a out.Mixing Scriptlets and HTML We have already seen how to use the "out" variable to generate HTML output from within a webkandii.com more complicated HTML, using the out variable all the time loses some of the advantages of JSP programming.
If you want to invoke some Java code to preprocess a request, e.g. preloading some list from a database to display in some table, if necessary based on some query parameters, then implement a servlet and write code accordingly in doGet() method. E.g. Hypertext Markup Language (HTML) is the standard markup language for creating web pages and web applications.