What is the difference between jsp and servlet

What is the difference between jsp and servlet? JSP is a Web page scripting language that can generate dynamic content, and Servlet is a compiled Java program that can also create dynamic Web content.

Servlet is a Java program that runs on the server side. Mainly accessed by browsers, it can display request results in HTML.

Although servlet describes HTML processing in the program, JSP has a mechanism in which the fragmented Java code embedded in the ".jsp" file has the same structure as HTML and is dynamically processed there .

The ".jsp" file is placed in the same directory as the content, and the "JSP tag" surrounded by <%~%> elements is described in the Java code section. In JSP, when a JSP program in HTML is called, a servlet is dynamically created and executed on the server.

JSP can easily display the effects of HTML through servlet. Embed Java into the HTML description instead of the Java-described image. Internally, it compiles with the first access and converts it into a servlet.

The above is not so much about advantages and disadvantages, but it is better to think that it is used according to different roles.

In current Web programming, the idea of ​​​​the MVC model is very common.

M···is the module. The part that defines the business logic (specific processing).

V··· is a view. It refers to the screen itself (HTML).

C···Control. It receives requests from the user to control the relationship between M and V (processing and displaying pictures).

Then JSP will be responsible for V (view) and servlet will be responsible for C (control).

Receive the request→Perform processing according to the request content. (M) → Display the processing results in JSP. (V)

Servlet will control the process above (C), and JSP will perform the final screen display part.

Since JSP is basically created in HTML, there can be a division of labor between designers and Java programmers (although it is not a complete division of labor).

Usually, when using servlet for surface display, it becomes troublesome to confirm the screen design. However, it can be easily done using JSP.

In addition, by dividing the labor, the amount of coding for the servlet is reduced, the source code can be easily seen, and it can also help debug where the problem occurs when it occurs.

JSP does not need to be compiled, but servlets always need to be compiled.

In the servlet, use the javac command to compile the source code to compile the ".java" file and generate the ".class" file.

The compiled ".class" file must be placed on the server.

JSP, on the other hand, operates by placing a ".jsp" file on the web server.

The servlet engine automatically converts the .jsp file into a servlet, compiles and executes it.

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