Basic knowledge of JSP syntax

1. JSP annotations

There are two main types of annotations in JSPs:

 Explicit Comment: <!--HTML Comment, client visible--(heavier transport burden, minimal use)
 implicit annotations:
 Format one://single-line comment
 Format two:/* */single-line or multiline comment
 Format three: <%--jsp comment, client not visible--%> JSP Comment
Example:
Write a JSP file that contains the above three types of annotations

2. Scriptlet (Script applet)

All Java programs that are embedded in HTML code must be marked with Scriptlet.
Scriptlet includes: small scripts, declarations, and expressions, which are described separately below.

(1) Small script: <%java code%>

 can write various statements in our Java application methods, including defining variables, but cannot write methods.
 Reason: The code will be converted into a method body in a class by the JSP engine, if the method is written, it is equivalent to the method body
Declares a method, so you cannot write a method in a small script.

For example:

In the JSP page, ask for 1-100 summation and output in the page:

(2) Statement: <%! Method%>

 define global constants, write methods, but not directly in <%! %> write any ordinary statement, because this part will be the JSP
The engine is converted into a method in a class.
 Note: JSP built-in objects cannot be used in this section.

For example:
Declares a method that formats a date, and the call displays the current date.

(3) Expression: <%=%>

 output A variable or a specific content.

For example:
It is better to use Out.print () and expressions to print a table of 10 rows and 10 columns on the page, respectively.
Out.print () Output:

Expression output: More concise, the foreground code is more structured, so recommend this way.

Basic knowledge of JSP syntax