JSP learning (2) -- JSP script elements and instructions

 

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1.0 jsp Script elements

Script element composition

1.1 Expression format

<%=java expression %>

1. No spaces

2. Non pluggable statement

3. Must be able to evaluate

4. Used to print variables or output values .

1.2 Scriptlet

Grammar format ：<%java Code %>

• No spaces

• Classes and methods cannot be defined

• Valid on current page , Will not be shared by other threads

• You can write in it java Code for . Definition java Variables and writing java sentence .

1.3 Statement

Grammar format <%! Function or constant %>

1. No spaces

2. Valid throughout the page , Will be shared by multiple threads

3. You can define global variables and methods in it , class .

2.0 Jsp Declaration and jsp scriptlet The difference between

count1 It's been accumulating , but count2 The value of does not change

2.1 Jsp Instructions

page Common attributes of instructions