blocks|key|797945|text|我认为servlet基本上是一个java类，它充当HTTP请求和HTTP之间的中间方式，response.Servlet也用来使你的网页动态化。假设，例如，如果您想要重定向到服务器上的另一个web页面，那么您必须使用servlet。另一件重要的事情是servlet可以在本地主机上运行，也可以在web浏览器上运行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|797946|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I think servlet is basically a java class which acts as a middle way between HTTP request and HTTP response.Servlet is also used to make your web page dynamic. Suppose for example if you want to redirect to another web page on server then you have to use servlets. Another important thing is that servlet can run on localhost as well as a web browser.

blocks|key|798002|text|Servlet是一个java类，用于响应HTTP请求并生成HTTP响应......当我们使用HTML制作一个页面时，它将是一个静态页面，所以为了使它变得动态，我们使用SERVLET+{简单地说，人们可以理解}为了利用servlet，JSP克服了它，它本身使用了代码和HTML标记。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|798003|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Servlet is a java class to respond a HTTP request and produce a HTTP response...... when we make a page with the use of HTML then it would be a static page so to make it dynamic we use SERVLET {in simple words one can understand}
To make use of servlet is overcomed by JSP it uses the code and HTML tag both in itself..

blocks|key|582125|text|除了以上这些，我要指出的是明显的出血。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|582126|对于许多人来说，这是非常明显的，但对于习惯于编写应用程序的人来说，这些应用程序只是运行然后结束:+servlet大部分时间都在闲逛，什么也不做……等待被发送的东西，一个请求，然后对它作出响应。由于这个原因，servlet有一个生命周期:它被初始化，然后等待，对抛给它的任何东西做出响应，然后被销毁。这意味着它必须由其他东西(框架)创建(然后销毁)，它在自己的线程或进程中运行，除非被要求，否则它什么也不做。而且，通过某种方式或其他方式，必须实现一种机制，借此该“实体”可以“监听”请求。|582127|我建议阅读有关线程、进程和套接字的内容将会对此有所启发:它与基本的"hello+world“应用程序的运行方式有很大的不同。|582128|有人可能会说，术语“服务器”或"servlet“有点过头了。一个更合理、更简单的名称可能是“响应者”。选择术语“服务器”的原因是历史的:最早的这种安排是“文件服务器”，其中多个用户/客户端终端将从中央机器请求特定的文件，然后该文件将像一本书或一盘炸鱼和薯条一样被“提供”。|582129|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

In addition to the above, and just to point out the bleedin' obvious...

To many this is hyper obvious, but to someone used to writing apps which are just run and then end: a servlet spends most of its time hanging around doing nothing... waiting to be sent something, a request, and then responding to it. For this reason a servlet has a lifetime: it is initalised and then waits around, responding to anything thrown at it, and is then destroyed. Which implies that it has to be created (and later destroyed) by something else (a framework), that it runs in its own thread or process, and that it does nothing unless asked to. And also that, by some means or other, a mechanism must be implemented whereby this "entity" can "listen" for requests.

I suggest that reading about threads, processes and sockets will throw some light on this: it's quite different to the way a basic "hello world" app functions.

It could be argued that the term "server" or "servlet" is a bit of an overkill. A more rational and simpler name might be "responder". The reason for the choice of the term "server" is historical: the first such arrangements were "file servers", where multiple user/client terminals would ask for a specific file from a central machine, and this file would then be "served up" like a book or a plate of fish and chips.

blocks|key|582169|text|Java+servlet是服务器端的Java程序模块，负责处理和响应客户的需求，并实现servlet接口。它有助于以可忽略的开销、维护和支持来提高Web服务器的有用性。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|582170|servlet充当客户和服务器之间的中介者。当servlet模块在服务器上持续运行时，它们可以获取并响应客户的请求。servlet的Demand和reaction对象提供了一种有用的方法来处理HTTP请求并将内容信息发送回客户。|582171|由于servlet与Java方言相协调，因此它还具有所有Java亮点，例如，高可移动性、阶段自主性、安全性和Java数据库可用性。|582172|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

Java Servlets are server-side Java program modules that procedure and answer customer demands and actualize the servlet interface. It helps in improving Web server usefulness with negligible overhead, upkeep and support. 

A servlet goes about as a mediator between the customer and the server. As servlet modules keep running on the server, they can get and react to demands made by the customer. Demand and reaction objects of the servlet offer a helpful method to deal with HTTP asks for and send content information back to the customer. 

Since a servlet is coordinated with the Java dialect, it additionally has all the Java highlights, for example, high movability, stage autonomy, security and Java database availability.

blocks|key|798233|text|正如this+article所描述的，Servlet是扩展Java服务器和访问其功能的标准化方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|798234|每个Servlet都可以看作是一个小服务器(由此得名)，它可以访问以Java代码建模的请求和响应，以及其他上下文数据，比如会话。|798235|有了这些，servlet的Java代码就可以与呈现响应所需的任何东西进行交互，包括传递给JSP页面以生成HTML视图。|798236|entityMap|0|LINK|mutability|MUTABLE|url|https://www.javaworld.com/article/3313114/learn-java/what-is-a-java-servlet-request-handling-for-java-web-applications.html^0|2|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

As <a href="https://www.javaworld.com/article/3313114/learn-java/what-is-a-java-servlet-request-handling-for-java-web-applications.html" rel="nofollow noreferrer">this article</a> describes, a Servlet is a standardized way of extending a Java server, and accessing its capabilities.

Each Servlet can be seen as a tiny server (hence the name), that gets access to the request and response modelled in Java code, along with other context data, like the Session.

With these in hand, the Java code of the servlet can interface with whatever it needs to to render a response, including handing off to a JSP page for generating a HTML view.

blocks|key|798309|text|Servlet是当网站用户从服务器请求URL时运行某些函数的Java类。这些函数可以完成将数据保存到数据库、执行逻辑和返回加载页面所需的信息(如JSON数据)等任务。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|798310|大多数Java程序使用main()方法，该方法在程序运行时执行代码。Java+servlets包含与main()方法类似的doGet()和doPost()方法。当用户向映射到该servlet的URL发出GET或POST请求时，就会执行这些函数。因此，用户可以为GET请求加载页面，或者存储来自POST请求的数据。|offset|length|style|CODE|798311|当用户发送GET或POST请求时，服务器将读取目录中每个servlet类顶部的@WebServlet，以决定调用哪个servlet类。例如，假设您有一个ChatBox类，并且在顶部有这样一个类：|798312|@WebServlet("/chat")
public+class+ChatBox+extends+HttpServlet+{|code-block|syntax|javascript|798313|当用户请求/chat+URL时，将执行您的ChatBox类。|798314|entityMap^0|0|B|6|1E|6|1P|7|1X|8|2T|3|2X|4|3M|3|42|4|0|5|3|9|4|13|B|0|0|5|5|L|7|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@$D|U|E|V|F|G]|$D|W|E|X|F|G]|$D|Y|E|Z|F|G]|$D|10|E|11|F|G]|$D|12|E|13|F|G]|$D|14|E|15|F|G]|$D|16|E|17|F|G]|$D|18|E|19|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1A|8|@$D|1B|E|1C|F|G]|$D|1D|E|1E|F|G]|$D|1F|E|1G|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|1H|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1I|8|@$D|1J|E|1K|F|G]|$D|1L|E|1M|F|G]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]]|R|$]]

Servlets are Java classes that run certain functions when a website user requests a URL from a server. These functions can complete tasks like saving data to a database, executing logic, and returning information (like JSON data) needed to load a page. 

Most Java programs use a <code>main()</code> method that executes code when the program in run. Java servlets contain <code>doGet()</code> and <code>doPost()</code> methods that act just like the <code>main()</code> method. These functions are executed when the user makes a <code>GET</code> or <code>POST</code> request to the URL mapped to that servlet. So the user can load a page for a <code>GET</code> request, or store data from a <code>POST</code> request. 

When the user sends a <code>GET</code> or <code>POST</code> request, the server reads the <code>@WebServlet</code> at the top of each servlet class in your directory to decide which servlet class to call. For example, let's say you have a ChatBox class and there's this at the top:

<pre><code>@WebServlet("/chat")
public class ChatBox extends HttpServlet {
</code></pre>

When a user requests the <code>/chat</code> URL, your <code>ChatBox</code> class with be executed.

I read many articles to understand Java servlet but I did not succeed.
Can you please give brief introduction of Java servlets (in easy language). What is a servlet? What are the advantages?
I can't understand the difference between server-side programming languages (PHP, ASP) and servlets.

What is Java Servlet?

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Java

为了理解Java servlet，我阅读了很多文章，但都没有成功。您能简单介绍一下Java servlet吗(用简单的语言)。什么是servlet？其优势是什么？我无法理解服务器端编程语言(PHP、ASP)和servlets之间的区别。

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