


I have always wanted to try a three-tier architecture. But I haven't done it yet, subconsciously I always feel that I am not strong enough. What is something as high-end as a three-tier architecture, something that a simpleton like me can get?
This time I finally mustered up the courage to do it slowly. The most I can do is spend more time checking Baidu, right?
First of all, give yourself a refresher on the three-tier architecture:
What is three-tier? Three-tier architecture (3-tier architecture) The three-tier architecture in the usual sense divides the entire business application into: presentation layer (Presentation layer), business logic layer (Business Logic Layer), and data access layer (Data access layer). The purpose of distinguishing levels is the idea of "high cohesion and low coupling". In software architecture design, the hierarchical structure is the most common and important structure. The layered structure recommended by Microsoft is generally divided into three layers, from bottom to top: data access layer, business logic layer (also called domain layer), and presentation layer.
This is how I understand it: the presentation layer is almost the interface we see = event
The logic layer is almost the way we implement events = method
= SQL statement for adding, deleting, checking and modifying the database
Let me try to build a hotel management system.
Step one:
As a high-end hotel management system. So this is not something that anyone who wants to see can see or operate. We need to make a landing page. Outsiders? Haha, let’s verify it first!
The login page interface is ready. The rest is the operation page;
I am also bold about the presentation layer. I made a UI
and wanted to call different interactive pages through extensions.
The following is the main code of the UI:
1 /// <summary> 2 /// 菜?????展? 3 /// 4 /// </summary> 5 /// <param name="sender"></param> 6 /// <param name="e"></param> 7 private void pictureBox1_Click(object sender, EventArgs e) 8 { 9 if (pictureBox1.Location.X < 0)10 {11 this.pictureBox1.Location = new System.Drawing.Point(210, 48);12 this.tabControl1.Location = new System.Drawing.Point(221, 48);13 this.tabControl1.Size -= new Size(209, 0);14 this.treeView1.Visible = true;15 //this.pictureBox1.AccessibleDescription = "??菜?";16 }17 else18 {19 this.pictureBox1.Location = new System.Drawing.Point(-10, 48);20 this.tabControl1.Location = new System.Drawing.Point(12, 48);21 this.tabControl1.Size += new Size(209,0); 22 this.treeView1.Visible = false;23 }24 }
1 /// <summary> 2 /// 工具?-?算器 3 /// </summary> 4 /// <param name="sender"></param> 5 /// <param name="e"></param> 6 private void ?算器ToolStripMenuItem_Click(object sender, EventArgs e) 7 { 8 Thread t0 = new Thread(BlackCatHotelManagerBLL.HotelManager.calc); 9 t0.Start();10 }11 //private System.Object lockThis = new System.Object();12 13 14 /// <summary>15 /// 工具?-?事本16 /// </summary>17 /// <param name="sender"></param>18 /// <param name="e"></param>19 private void ?事本ToolStripMenuItem_Click(object sender, EventArgs e)20 {21 Thread t1 = new Thread(BlackCatHotelManagerBLL.HotelManager.notepad);22 t1.Start();23 }
to be continued. . .

The function of HTML is to define the structure and content of a web page, and its purpose is to provide a standardized way to display information. 1) HTML organizes various parts of the web page through tags and attributes, such as titles and paragraphs. 2) It supports the separation of content and performance and improves maintenance efficiency. 3) HTML is extensible, allowing custom tags to enhance SEO.

The future trends of HTML are semantics and web components, the future trends of CSS are CSS-in-JS and CSSHoudini, and the future trends of JavaScript are WebAssembly and Serverless. 1. HTML semantics improve accessibility and SEO effects, and Web components improve development efficiency, but attention should be paid to browser compatibility. 2. CSS-in-JS enhances style management flexibility but may increase file size. CSSHoudini allows direct operation of CSS rendering. 3.WebAssembly optimizes browser application performance but has a steep learning curve, and Serverless simplifies development but requires optimization of cold start problems.

The roles of HTML, CSS and JavaScript in web development are: 1. HTML defines the web page structure, 2. CSS controls the web page style, and 3. JavaScript adds dynamic behavior. Together, they build the framework, aesthetics and interactivity of modern websites.

The future of HTML is full of infinite possibilities. 1) New features and standards will include more semantic tags and the popularity of WebComponents. 2) The web design trend will continue to develop towards responsive and accessible design. 3) Performance optimization will improve the user experience through responsive image loading and lazy loading technologies.

The roles of HTML, CSS and JavaScript in web development are: HTML is responsible for content structure, CSS is responsible for style, and JavaScript is responsible for dynamic behavior. 1. HTML defines the web page structure and content through tags to ensure semantics. 2. CSS controls the web page style through selectors and attributes to make it beautiful and easy to read. 3. JavaScript controls web page behavior through scripts to achieve dynamic and interactive functions.

HTMLisnotaprogramminglanguage;itisamarkuplanguage.1)HTMLstructuresandformatswebcontentusingtags.2)ItworkswithCSSforstylingandJavaScriptforinteractivity,enhancingwebdevelopment.

HTML is the cornerstone of building web page structure. 1. HTML defines the content structure and semantics, and uses, etc. tags. 2. Provide semantic markers, such as, etc., to improve SEO effect. 3. To realize user interaction through tags, pay attention to form verification. 4. Use advanced elements such as, combined with JavaScript to achieve dynamic effects. 5. Common errors include unclosed labels and unquoted attribute values, and verification tools are required. 6. Optimization strategies include reducing HTTP requests, compressing HTML, using semantic tags, etc.

HTML is a language used to build web pages, defining web page structure and content through tags and attributes. 1) HTML organizes document structure through tags, such as,. 2) The browser parses HTML to build the DOM and renders the web page. 3) New features of HTML5, such as, enhance multimedia functions. 4) Common errors include unclosed labels and unquoted attribute values. 5) Optimization suggestions include using semantic tags and reducing file size.


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