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This article is to share with you about the usefulness of Java Servlet. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

The following figure shows the location of Servlet in the Web application.

Definition of 1.Servlet:

Server Mini Program is a server-side program written in Java, which is requested by the client, invoked and executed by the server. The parent class is GenericServlet or HttpServlet.

Life cycle of 2.servlet

(initialization phase, run phase, destroy phase) when a servlet is requested for the first time, the server automatically loads and instantiates the servlet and completes some initialization of the servlet; when a request arrives at the container, the container looks for the corresponding servlet instance, then creates a thread, calls the service method, the doGt,doPost method according to this thread, and calls the destroy method to destroy the servlet after the call finishes

The difference between 3.Servlet and JavaBean:

The former is loaded by the server and the latter is loaded by the user program. Servlet must inherit from HttpServlet and override service or doGet or doPost methods and be configured in web.xml; Javabean is a normal Java class that adds getter and setter to the properties and provides default constructs. Can exist in all layers of a multi-tier architecture. You can do whatever you want with it. While Servlet is in the presentation layer, it should only exist in the presentation layer. It is often used as a controller in MVC.

4.Java Servlet can usually achieve the same effect as a program implemented using CGI (Common Gateway Interface, Common Gateway Interface). But compared with CGI,Servlet, it has the following advantages:

1. The performance is obviously better.

2.Servlet is executed in the address space of the Web server. This eliminates the need to create a separate process to handle each client request.

3.Servlet are platform independent because they are written in Java.

4. The Java Security Manager on the server enforces a series of restrictions to protect resources on the server computer. Therefore, Servlet is credible.

The full functionality of the 5.Java class library is available to Servlet. It can interact with applets, database, or other software through sockets and RMI mechanisms.

The main tasks of 5.Servlet are:

1. It reads explicit data sent by the client (browser). This includes HTML forms on a web page, or forms from applet or a custom HTTP client program.

two。 Read implicit HTTP request data sent by the client (browser). This includes cookies, media types, compressed formats that browsers can understand, and so on.

3. Process the data and generate the results. This process may require accessing the database, making RMI or CORBA calls, invoking Web services, or directly calculating the corresponding response.

4. Send explicit data (that is, documents) to the client (browser). The document can be in a variety of formats, including text files (HTML or XML), binaries (GIF images), Excel, and so on.

5. Send an implicit HTTP response to the client (browser). This includes telling browsers or other clients the type of document to be returned (such as HTML), setting cookies and cache parameters, and other similar tasks.

Thank you for reading! This is the end of this article on "what's the use of Java Servlet?". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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