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This article mainly introduces the JSP life cycle through which stages of the relevant knowledge, the content is detailed and easy to understand, the operation is simple and fast, has a certain reference value, I believe that after reading this JSP life cycle through which stages of the article will have a harvest, let's take a look.

The JSP life cycle is the whole process from creation to destruction, similar to the servlet life cycle, except that the JSP life cycle also includes compiling JSP files into servlet.

Here are several phases of the JSP lifecycle:

Compilation phase:

The servlet container compiles the servlet source file to generate the servlet class

Initialization phase:

Load the servlet class corresponding to JSP, create its instance, and call its initialization method

Execution phase:

Call the service method of the servlet instance corresponding to JSP

Destroy phase:

Call the destroy method of the servlet instance corresponding to JSP, and then destroy the servlet instance

Obviously, the four main phases of the JSP life cycle are very similar to the servlet life cycle, as shown below:

Img1.JSP compilation

When the browser requests a JSP page (browsing URL through the browser? When the JSP engine (? Will first check to see if the file needs to be compiled If the file has not been compiled, or has been changed since the last compilation, the JSP file is compiled. (convert and compile servlet)

The compilation process consists of three steps:

Parse the JSP file. Convert the JSP file to servlet. Compile servlet. 2.JSP initialization

Container (? After loading the JSP file, it calls the jspInit () method before providing any services to the request. If you need to perform a custom JSP initialization task, just override the jspInit () method, like this:

Public void jspInit () {/ / initialization code}

Generally speaking, the program is initialized only once, and so is servlet. Typically you can initialize a database connection, open a file, and create a query table in the jspInit () method.

3.JSP execution

This phase describes all request-related interactions in the JSP life cycle until it is destroyed.

When the JSP page is initialized, the JSP engine (? The _ jspService () method will be called.

The _ jspService () method requires a HttpServletRequest object and a HttpServletResponse object as its parameters, like this:

Void _ jspService (HttpServletRequest request, HttpServletResponse response) {/ / server processing code}

The _ jspService () method is used in each request (? Is called once and is responsible for generating the corresponding response, and it is also responsible for generating responses to all seven HTTP methods, such as GET, POST, DELETE, and so on. * (do not understand this process?) ***

4.JSP cleanup

The destroy phase of the JSP life cycle describes what happens when a JSP page is removed from the container.

The destruction method of the jspDestroy () method in JSP and servlet. Override the jspDestroy () method when you need to perform any cleanup, such as releasing a database connection or closing a folder, and so on.

The format of the jspDestroy () method is as follows:

Public void jspDestroy () {/ / Clean Code} this is the end of the article on "how many stages has the JSP life cycle gone through?" Thank you for reading! I believe you all have a certain understanding of the knowledge of "which stages of the JSP life cycle". If you want to learn more knowledge, you are welcome to follow the industry information channel.

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