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What's a Java Server Page?
How Does a JSP Work?
Do JSPs Replace Servlets?
JSP Expressions vs. Scriplets
Conditional JSPs
JSP Declarations
A JSP Hit Counter
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As you've already seen, Java Servlets are Java classes which typically
contain many print statements to output HTML (or other) content. In other
words, the HTML is embedded inside the servlet's Java code.
It is not uncommon to have more HTML than Java code. This is a problem
for a number of reasons:
- You often have different developers involved in HTML vs. Java code.
HTML experts often know little to nothing about Java, and vice versa.
Often, the HTML experts are graphic designers, who know how to make a web
site look attractive. Java experts know code, but are often more
look-and-feel challenged.
- There are different sets of tools for HTML development vs. Java
development. Embedding HTML inside Java precludes using these (often very
good, and time-saving) HTML tools, such as Dreamweaver, etc.
- In a large project, you need to be able to separate out the work in order
to feed it to the appropriate person/group. Embedding HTML in Java
doesn't help with this.
- It's very important to separate form from function. A web
application's look and feel (as reflected in a web site) should have little
or no effect on how it is implemented behind the scenes. Web sites'
look and feel are often changed; such changes should have minimal
impact on the implementation.
As a result, Java Server Pages (JSPs) were invented.
With JSPs, we reverse the situation:
- We embed Java code inside an HTML page.
For similar reasons to the above, however, we don't want to place a lot of
Java code inside an HTML page. That also makes things hard to manage.
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