JavaServer Pages (JSP) Overview and its Elements

What is JSP?

JavaServer Pages (JSP) is a technology that helps developers create dynamic, data-driven web pages. JSP pages are compiled into Java servlets and run on the server.

JSP uses a special syntax that embeds snippets of Java code within HTML, and these pages are stored as regular HTML files with a .jsp extension. This code is known as a JSP action.

JSP actions are executed when a user requests the page.

These pages are well suited for use in a distributed environment offering a high degree of flexibility.

JSP pages offer many benefits over traditional HTML pages, such as:

• JSP pages can be easily created and maintained.
• JSP is capable of producing dynamic content, but HTML is not.
• JSP provides excellent performance and scalability.
• The separation of visual logic and functionality makes it easier to manage.

JSP pages are executed on the server by a JSP engine, which translates the JSP tags into HTML code, then it is sent to the client's browser.

JSP syntax is similar to HTML and includes unique attributes allowing Java code to be executed.

JSP tags

JSP pages can contain various tags, which are used to embed Java code in the page. JSP action tags, which allow you to put Java code into the page, are the most often used tags.

Other tags include the JSP directive tags, which are used to set page options, and the JSP scripting tags, which are used to add JavaScript code to the page.

JSP composition

JSP uses a template file combined with a Java code file to create a web page. The template file contains the static content of the web page, and the Java code file contains the dynamic content.

When the web page is requested, the server reads the template file and merges it with the Java code file to create the HTML output.

JSP Architecture in Java

The JSP architecture is based on the Model-View-Controller (MVC) design pattern, separating the page's content from its presentation. This makes it possible to easily change the page's look without modifying the underlying code.

The JSP architecture consists of three main components:

• The client requests a JSP page.
• The JSP engine processes the JSP page and generates a response.
• The JSP container manages the lifecycle of JSP pages and servlets.

JSP pages are typically used to display data from a database. The JSP engine reads the JSP and converts it into a servlet. The Servlet then accesses the database and retrieves the data. The data is then passed to the JSP page, which displays it to the user.

The Servlet is cached and reused for subsequent requests when JSP is first accessed. This enables the JSP page to be displayed quickly, without having to access the database each time.

The JSP architecture is flexible and can be customized to meet the needs of your application. For example, you can use JSP pages to create RSS feeds or generate PDF files.

JSP life cycle

JSP pages follow a life cycle that begins when the page is first requested. During the life cycle, the JavaServer Page is compiled and executed. The page is then cached and can be promptly accessed the next time it is requested.

The life cycle includes the following steps:

1. The client accesses the JSP page.
2. The JSP page is compiled into a servlet by the JSP engine.
3. The web server executes the Servlet.
4. The Servlet generates HTML output, which is sent back to the client.

JSP vs Servlet

Servlets are the foundation of JavaServer Pages. Servlet extends the javax.servlet.http.HttpServlet class and implements the doGet() and doPost() methods.

The doGet() method is invoked by the browser when the user requests a page, and the doPost() method is invoked when the user submits a form.

There are a few key differences between JSP and servlets that you should be aware of,

• JSP is a technology for dynamically generating web pages, while servlets are technologies for encoding web page requests and responses.
• JSP pages are compiled into servlets by the web container, while servlets are compiled into bytecode that can be run on a Java virtual machine.
• Clients can invoke JSP pages directly, while servlets must be invoked indirectly through a web server.

Conclusion

If you want to develop a web application with dynamic content, JSP can assist you in getting there quickly.

However, the technique is outdated compared to new technological developments, which have enabled developers to achieve the same objectives with additional flexibility. Yet, server-side programming is a crucial aspect of Java learning that everyone should cover.

Turing's knowledge hub contains additional learning resources on numerous programming languages that can assist you in honing your development abilities.