The learning website is from www.imooc.com
Servlet Basics
1. What is Servelet?
Servelet is a small program running on the server. A Servlet is a Java class
, and the Servlet program that resides in the server memory
can be accessed through the "request-response" programming model. Servlet is the predecessor of jsp.
2. Tomcat container levels
Tomcat containers are divided into four levels. The Servlet container manages the Context container, and one
Context corresponds to a Web project. Engine is an engine container; Host is a host container.
3. Writing a Servlet
is divided into three steps.
1. Write a class that inherits HttpServlet
2. Override the doGet() or doPost() method; depending on the submission method.
3. Register Servlet in web.xml.
The procedure is as follows:
Code in index.jsp:
<body> <h1 id="第一个Servlet小例子">第一个Servlet小例子</h1> <hr> <!-- 用get方式请求，写一个超链接就可以了;超链接访问就是get请求--> <a href="servlet/HelloServlet">get方式请求HelloServlet</a><br> <!-- 用post方式，做一个表单就可以实现 --> <form action="servlet/HelloServlet" method="post"> <input type="submit" value="post方式请求HelloServlet"/> </form> </body>
HelloServlet.java Code in:
package Servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//继承于HttpServletpublic class HelloServlet extends HttpServlet {//重写方法 @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.println("处理Get()请求..."); //获得一个给浏览器输出的对象out,类型为 PrintWriter PrintWriter out = response.getWriter(); //指定输出文件的类型 response.setContentType("text/html;charset=utf-8"); //用out对象给浏览器输出一个信息。可以在里面用html的代码 out.println("<strong>Hello Servelet!</strong><br>"); //3.注册；在WEB-INF里面的web.xml中注册 } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.println("处理post()请求..."); //获得一个给浏览器输出的对象out,类型为 PrintWriter PrintWriter out = response.getWriter(); //指定输出文件的类型 response.setContentType("text/html;charset=utf-8"); //用out对象给浏览器输出一个信息。可以在里面用html的代码 out.println("<strong>Hello Servelet!post</strong><br>"); //3.注册；在WEB-INF里面的web.xml中注册；已经注册完 就不用重复 }} Registration code in web.xml:
The registration process is to add two tags
< in web.xml ;servlet> and
and each tag must contain two sub-tags
in
and
> ;
In
Servlet a name (note: it must be the same as the name above) and
The path visited by Servlet
<servlet> <servlet-name>HelloServlet</servlet-name> <servlet-class>Servlet.HelloServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>HelloServlet</servlet-name> <url-pattern>/servlet/HelloServlet</url-pattern> </servlet-mapping>
HTML, CSS, and JavaScript: Examples and Practical ApplicationsMay 09, 2025 am 12:01 AMThe roles of HTML, CSS and JavaScript in web development are: 1. HTML is used to build web page structure; 2. CSS is used to beautify the appearance of web pages; 3. JavaScript is used to achieve dynamic interaction. Through tags, styles and scripts, these three together build the core functions of modern web pages.
How do you set the lang attribute on the tag? Why is this important?May 08, 2025 am 12:03 AMSetting the lang attributes of a tag is a key step in optimizing web accessibility and SEO. 1) Set the lang attribute in the tag, such as. 2) In multilingual content, set lang attributes for different language parts, such as. 3) Use language codes that comply with ISO639-1 standards, such as "en", "fr", "zh", etc. Correctly setting the lang attribute can improve the accessibility of web pages and search engine rankings.
What is the purpose of HTML attributes?May 07, 2025 am 12:01 AMHTMLattributesareessentialforenhancingwebelements'functionalityandappearance.Theyaddinformationtodefinebehavior,appearance,andinteraction,makingwebsitesinteractive,responsive,andvisuallyappealing.Attributeslikesrc,href,class,type,anddisabledtransform
How do you create a list in HTML?May 06, 2025 am 12:01 AMTocreatealistinHTML,useforunorderedlistsandfororderedlists:1)Forunorderedlists,wrapitemsinanduseforeachitem,renderingasabulletedlist.2)Fororderedlists,useandfornumberedlists,customizablewiththetypeattributefordifferentnumberingstyles.
HTML in Action: Examples of Website StructureMay 05, 2025 am 12:03 AMHTML is used to build websites with clear structure. 1) Use tags such as, and define the website structure. 2) Examples show the structure of blogs and e-commerce websites. 3) Avoid common mistakes such as incorrect label nesting. 4) Optimize performance by reducing HTTP requests and using semantic tags.
How do you insert an image into an HTML page?May 04, 2025 am 12:02 AMToinsertanimageintoanHTMLpage,usethetagwithsrcandaltattributes.1)UsealttextforaccessibilityandSEO.2)Implementsrcsetforresponsiveimages.3)Applylazyloadingwithloading="lazy"tooptimizeperformance.4)OptimizeimagesusingtoolslikeImageOptimtoreduc
HTML's Purpose: Enabling Web Browsers to Display ContentMay 03, 2025 am 12:03 AMThe core purpose of HTML is to enable the browser to understand and display web content. 1. HTML defines the web page structure and content through tags, such as, to, etc. 2. HTML5 enhances multimedia support and introduces and tags. 3.HTML provides form elements to support user interaction. 4. Optimizing HTML code can improve web page performance, such as reducing HTTP requests and compressing HTML.
Why are HTML tags important for web development?May 02, 2025 am 12:03 AMHTMLtagsareessentialforwebdevelopmentastheystructureandenhancewebpages.1)Theydefinelayout,semantics,andinteractivity.2)SemantictagsimproveaccessibilityandSEO.3)Properuseoftagscanoptimizeperformanceandensurecross-browsercompatibility.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.
SublimeText3 Mac version
God-level code editing software (SublimeText3)
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
Notepad++7.3.1
Easy-to-use and free code editor
WebStorm Mac version
Useful JavaScript development tools
