Advantages, Disadvantages and Basic Operations of JSP-javaTutorial-php.cn

Advantages, Disadvantages and Basic Operations of JSP

巴扎黑

Release： 2017-07-17 13:24:59

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The first day:

jsp (full name Java Server Pages)

Advantages:

　Cross-platformability, Ease of maintenance, ease of management, etc.

In fact, JSP refers to embedding JAVA script language in HTML. When the user requests to access the Web application through the browser, the JSP container is used to request the JSP, and then the JSP is processed. The generated page is returned to the client browser for display.

Working principle

Execution principle

If no change occurs Then

What is a URL?

URL (Uniform Resoure Locator) Uniform Resource Locator is a representation method used to completely describe the address of web pages and other resources on the Internet, that is, a URL.

URL composition

tomcat7.0
lib 　　jar
bin　　Command
webapps 　　 Application
work 　　Working directory
temp Temporary file
conf Configuration file
logs Log file
Tomcat and myeclipse configuration

window
showview
console
db brower
package explorer
servers

Basic of JSP Syntax

Command

　<%@ import="java.sql.*"%>

page command

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　ccogateous , indicating the programming language used in the script <strong></strong>

　　 contentType : Set the type of content and the encoding of the static page (tell the browser in what encoding to display) <strong></strong>

pageEncoding: Page Its own encoding format (the encoding format used when writing pages)

##　 include directive<strong></strong>
                                                                                                                                                                                                        Include the content of the target page into the current page, producing the output effect after the page is superimposed //Equivalent to merging two pages; compile Include it when 
##            <%@include file="foot. jsp"%> 　　　　　　　　//Can be inserted anywhere
Small script
　<% %> Writing java code is equivalent to writing code in the service method of index.java
 Mini script rules: 
　　1. The scripting language you use determines the rules of the script applet;
　　2. Statements are separated by semicolons; 
 3. You can use the default object, the imported class, the methods and objects declared by declaration, and the objects declared in the useBean tag. 

Statement
　<%! %>Writing Java code is equivalent to writing Java code in the index.java class, outside the service method Write code
　Declaration rules:
　1. The variables and methods declared in JSP correspond to the instance methods and instance variables in the Servlet. These will be shared by all users who request the page at the same time; 
 2. Variables or methods must be defined before using them (it does not mean that the position where the variables are declared must be in front of the used variables in the page. It means that the variable cannot be used if it is not declared);
　3. The scope of the declared variable or method is the current page or the included page;
　4. Between statements Separate with semicolons. 
Expression
　<%= %>Identical<%out.println();%>
 Expression rules: 
 1. The scripting language you use determines the rules of the script applet;
 2. The order of execution is from left to right; <strong></strong>
 3. Semicolons cannot be used in expressions. <strong></strong>
##Comments
　jsp<%--Content--%> will not be translated
<strong></strong>　html will not be displayed
<strong></strong>　java comment:// /* */ will not be compiled
<strong></strong> 

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