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This article introduces the relevant knowledge of "how to realize view layer separation in MVC". In the operation process of actual cases, many people will encounter such difficulties. Next, let Xiaobian lead you to learn how to deal with these situations! I hope you can read carefully and learn something!

what is MVC

MVC pattern, is the original web code, according to the different functions, divided into control layer, view layer and model layer three levels, take web project as an example, when the request to access, the control layer is responsible for processing, the control layer calls the model layer to process the request, and finally use the presentation layer to display it.

actual combat

Request page: (This is the page used for requests, put out for reference)

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servlet (here we use servlet version 3.0 and above, using annotations instead of web.xml):

import java.io.*; import javax.servlet.http.*; import javax.servlet.annotation.*;@ WebServlet(name = "helloServlet", value = "/hello-servlet")public class HelloServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { String classname = ""; String url = ""; String element = ""; classname = request.getParameter("class"); if (classname.equals("qd")) {//currently only do front-end judgment, add later url = "https://www.yisu.com/courses? direction=2120&tag=0&type=&condition=&order="; element = "front-end mini-lesson"; } response.setContentType("text/html"); response.setCharacterEncoding("utf-8"); PrintWriter out = response.getWriter(); out.println("\n" + "\n" + "\n" + "\t\n" + "\t\n" + "\t\n" + "\tDocument\n" + "\n" + ""); out.println("The following is an introduction to the excellent front-end microcourses of W3C platform, click the link to go"); out.println("" + element + ""); out.println(""); }}

As you can see, the above code uses servlets to output HTML code, which is very confusing and mixed with some decisions (this part of the function should be handled by the model layer). Next, we will strip the html code and use jsp to output the page.

result.jsp (jsp responsible for returning pages):

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At the same time, the servlet is modified accordingly (mainly removing the original HTML output code, encapsulating the data that needs to be passed to the page into the request and then forwarding the request to the jsp).

The current servlet get method is as follows:

public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { String classname = ""; String url = ""; String element = ""; classname = request.getParameter("class"); if (classname.equals("qd")) {//currently only do front-end judgment, add later url = "https://www.yisu.com/courses? direction=2120&tag=0&type=&condition=&order="; element = "front-end mini-lesson"; } request.setAttribute("url",url); request.setAttribute("element",element); RequestDispatcher view = request.getRequestDispatcher("result.jsp"); try { view.forward(request,response); } catch (ServletException e) { e.printStackTrace(); } }

This completes the separation of the view layers.

"MVC how to achieve view layer separation" content is introduced here, thank you for reading. If you want to know more about industry-related knowledge, you can pay attention to the website. Xiaobian will output more high-quality practical articles for everyone!

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