The Java Web: An Opening Overview and Chapter 1

foreword

Opening this book is another new learning route. On the road of learning, it is boring and tedious, and it is inevitable to have the idea of giving up. But looking back at the previous study notes, I have come step by step. Even if I doubt myself and deny myself, there will never be results if I don’t persist or work hard. Please remember: If you don’t accumulate steps, you won’t reach a thousand miles; There is no way to become a river. The future is bright, the road is tortuous, I believe tomorrow will be better!

learning path

The main learning routes of Java Web are:

Java Web Foundation---->mysql---->Spring boot and other mainstream frameworks---->Project combat and development---->JVM

review

There are four main chapters in this book, web basic development, JSP basics, JSP advanced, mainstream framework

1. On the basis of web development (article), the four chapters mainly include the following contents:

Overview of Java Web Application Development (Chapter)
HTML and CSS Web Development Fundamentals
JavaScript scripting language
Build the development environment

Two, JSP language foundation

Three, JSP advanced content

4. Popular framework

The first web development basics

Chapter 1 Overview of Java web application development

1. Program development architecture

1.1 Mainly divided into two major architectures: B/S structure, C/S structure

C/S

C/S is the abbreviation of Client/Servers. It is a client/server model. High-performance servers and databases (Oracle or SQL Server) are selected. The client needs to install special software to interact with the server.

B/S

B/S is the abbreviation of Browser/Server, which is a browser/server mode. Customers only need to use a browser to send requests to the Web server through the Web browser, and the Web server will return the processing results step by step.

1.2 How web applications work

Mainly for static websites and dynamic websites.

Static websites: Static websites are mainly written in HTML. In static web programs, the client uses a web browser (IE, FireFox, etc.) to initiate a request using the HTTP protocol, telling the server which page I need to get now, and then the web server according to the user As needed, the content is fetched from the file system (disk where all static pages are stored). Afterwards, it is returned to the client through the web server, and after the client receives the content, it is rendered and parsed by the browser to obtain the displayed effect.

Notice:

Static web pages cannot connect to the database

Using javascript/VBScript/ajax to make static pages have special effects is also a static page, which is only presented to users on the client side. Dynamic web pages are interactive, not dynamic web pages.

Written mostly in HTML

Dynamic web page: The content needs to dynamically generate page information according to the user's request.

Execution process: The client makes an HTTP request through the browser and processes it through the WEB Server Plugin (server plug-in). This plug-in is used to distinguish whether the request is a static resource (*.htm or *.htm) or a dynamic resource.

If the WEB Server Plugin finds that the client requests dynamic resources (*.jsp, *.asp/*.aspx, *.php), it will first forward the request to the WEB Container (WEB container), and connect to the database in the WEB Container. After a series of operations such as fetching data from the database, the display content of the page is dynamically pieced together. After the display content of the page is pieced together, all the display content is handed over to the WEB server, and then the content is sent back to the client browser through the WEB server for parsing and execution.

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1.3 Web application technology

There are two technologies of client and server, which can be understood as front-end and back-end. That is, the client mainly performs information display , while the server mainly performs business logic processing and database interaction.

Client technology:

HTML language mainly displays page information, which is the basic framework of the page

CSS (Cascading Style Sheet) style sheet technology can effectively control the page layout, font, color and other effects precisely

Flash Flash is an interactive vector animation production technology, which can contain animation, audio, etc., to make the page more expressive

Client-side scripting technology Client-side scripting technology refers to the program code embedded in the web page, which realizes the control of the page elements through the scripting language , so as to increase the flexibility of the page elements. Usually JavaScript, VBScript.

Server technology:

CGI Common Gateway Interface, the common gateway interface. Allows writing in different languages. It enables an interactive relationship between the browser and the server. When the client sends a request to the server. The server executes the specified CGI program according to the process requested by the user, and transmits the result to the client browser in the form of a web page.

ASP Active Server Page is a widely used technology for developing dynamic websites, and generates dynamic content through scripting language.

PHP

ASP.NET is a technology for building dynamic web applications

JSP Java Server page, JSP is developed based on Java. The HTML code of the page is used to implement the static part, and the Java code and JSP tags of the page are embedded to generate the dynamic content part.