Detailed explanation of the principles and differences between static pages and dynamic pages

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One 、 static state web page

1、 In static Web In the program , Client side usage Web browser （IE、FireFox etc. ）, Use HTTP The protocol initiates a request , Tell the server which page I need to get now , after WEB Server according to the needs of users , From file system （ The disk that holds all the static pages ） Take out the content . After through Web The server returns to the client , After the client receives the content, it is rendered and parsed by the browser , Get the effect shown .

2、 To make it static web The page looks better , Use javascript／VBScript／ajax, But these special effects are displayed to users on the client side with the help of a browser , So there's no change in the server itself .

3、 static state web Unable to connect to database ;

4、 static state web Resource development technology ：HTML;

5、 Because of the present web On the page , A lot of use JS, Causes the browser to open the page , It takes up a lot of memory , The pressure on the server is reduced , But the pressure shifted to the client .

Two 、 dynamic web page

1、 dynamic WEB in , The program still uses the client and the server , The client still uses the browser （IE、FireFox etc. ）,, Use HTTP The agreement initiates the request , Now all the requests go through one WEB Server To deal with it .

2、 If the client requests static resources (.htm Or is it .htm), The request is forwarded directly to WEB The server , after WEB The server pulls content from the file system , Send it back to the client browser for parsing execution .

3、 If the client requests dynamic resources （.jsp、.asp/.aspx、.php）, Then forward the request to WEB Container(WEB Containers ), stay WEB Container Connect to database , After a series of operations, such as fetching data from the database, the display content of the dynamic patching page , After piecing together the display content of the page , Give all the presentation to WEB The server , After through WEB The server sends the content back to the client browser for parsing .

Further in-depth analysis of the dynamics web Access process ： Browser access web when , It seems to be directly accessed jsp page , It's actually , The first place to arrive is the server , The server is created req and resp Object before giving jsp Page using . stay jsp After setting the character set and obtaining the form parameters, call servlet, Complete business processing . Then return to jsp,jsp It will generate the corresponding html page . This page will return to the server , And then by the server , adopt response Object returned to client .
Why web The server ？(web server)

1） No matter what web resources , Want to be accessed by a remote computer , There must be a corresponding network communication program , When users come to visit , This network communication program reads web Resource data , And send the data to the visitors .

2）WEB The server is such a program , It is used to complete the underlying network communication , Handle http agreement . Use these servers ,We Application developers only need to pay attention web How to write resources , You don't need to care about how resources are sent to the client , This greatly reduces the development workload of developers .

Common news web Resource development technology ：JSP/Servlet、ASP、PHP etc. .

3、 ... and 、 On the difference between the two

1、 Static page is that the designer sets everything on the page 、 Then put it on , No matter who sees the page content at any time （ Unless you manually modify the content of the page ）. static state html pagefile , You can open it directly with your local browser . such as ：file:///Users/Phil/Documents/DevOps/HBuilderProjects/testJSP/index.html.

2、 The contents of dynamic pages are generally generated by server-side programs , Different people 、 Visit the page at different times , The content displayed may be different . After the web designer has written the page program on the server side , No manual control is required , The page content will be automatically changed and transformed according to the arrangement of the page program .

3、html yes w3c A standard web page writing format , Is a unified protocol language , Static web page . The web pages we read online are mostly based on html Linguistic .
jsp It is based on dynamic language ,jsp Can achieve html All the tasks of ,

4、HTML（Hypertext Markup Language） Text markup language , It's a static page , and JavaScript The same interpretative language , Why is it interpretative language ？ because , As long as you have a browser, it can be displayed normally , You don't need to specify a compiler , Just in TXT Write... In the document HTML The mark can be displayed normally .
JSP（Java Server Page） yes Java Server side page , So it's dynamic , It needs to go through JDK After compiling, send the content to the client to display , We all know ,Java After the file is compiled, a class file , This is the final execution class file .

5、JSP The predecessor was servlet;

6、html and jsp The header is different , This is JSP The head of the “ <%@ page language=“java” import=“java.util.*” pageEncoding=“gbk”%>” In the header, there are coding format, pouring package, etc . It's also easy to distinguish , stay jsp of use <%%> You can write Java Code. , and html No, <%%>.

7、, incognizance jsp perhaps asp What's that , But sometimes the interface needs logical control , So we use the corresponding technology to realize , This is more convenient . and jsp In the background, it is resolved to the corresponding... Through the server html, Then it is displayed for the browser to recognize . for example

<%
if(flag == a){
    
<label>a<label>
}else {
    
<label>b<label>
}
%>

After the server reads this code , According to the corresponding business logic , Compile into the corresponding servlet, Again by servlet Output to page （ The output is html）.

Four 、 Experimental tests

1、 stay HBuilder Created in jsp page , It's built in web Static server cannot resolve jsp Header , Output can only be displayed as text , But you can parse the html part . The browser cannot be opened directly jsp file .jsp If the page wants to display correctly , need web The container is parsed .

2、 stay IntelliJ Created in web application, Need to start the tomcat, To run jsp, It can be parsed smoothly jsp The header .

Last

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