项目实战：新增@RequestMapping和@GetMapping和@PostMapping三个注解

1、@RequestMapping

package com.csdn.mymvc.annotation;
import java.lang.annotation.*;
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface RequestMapping {
    String value();
}

2、@PostMapping

package com.csdn.mymvc.annotation;
import java.lang.annotation.*;
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface PostMapping {
    String value();
}

3、@GetMapping

package com.csdn.mymvc.annotation;
import java.lang.annotation.*;
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface GetMapping {
    String value();
}

4、FruitController

• 之前是FruitServlet现在不让他成为Servlet，改名成FruitController，不在继承HttpServlet

package com.csdn.fruit.servlet;
import com.csdn.fruit.dto.PageInfo;
import com.csdn.fruit.dto.PageQueryParam;
import com.csdn.fruit.dto.Result;
import com.csdn.fruit.pojo.Fruit;
import com.csdn.fruit.service.FruitService;
import com.csdn.fruit.service.impl.FruitServiceImpl;
import com.csdn.fruit.util.RequestUtil;
import com.csdn.fruit.util.ResponseUtil;
import com.csdn.mymvc.annotation.GetMapping;
import com.csdn.mymvc.annotation.PostMapping;
import com.csdn.mymvc.annotation.RequestMapping;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
@RequestMapping("/fruit")
public class FruitController {

    private FruitService fruitService = new FruitServiceImpl();

    @GetMapping("/index")
    protected void index(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Integer pageNo = 1;
        String pageNoStr = req.getParameter("pageNo");
        if (pageNoStr != null && !"".equals(pageNoStr)) {
            pageNo = Integer.parseInt(pageNoStr);
        }

        String keyword = "";
        String keywordStr = req.getParameter("keyword");
        if (keywordStr != null) {
            keyword = keywordStr;
        }
        PageQueryParam pageQueryParam = new PageQueryParam(pageNo, 5, keyword);
        PageInfo pageInfo = fruitService.getFruitPageInfo(pageQueryParam);

        Result result = Result.OK(pageInfo);

        ResponseUtil.print(resp, result);
    }

    @PostMapping("/add")
    protected void add(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Fruit fruit = (Fruit) RequestUtil.readObject(req, Fruit.class);
        fruitService.addFruit(fruit);
        ResponseUtil.print(resp, Result.OK());
    }

    @GetMapping("/del")
    protected void del(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Integer fid = Integer.parseInt(req.getParameter("fid"));
        fruitService.delFruit(fid);
        ResponseUtil.print(resp, Result.OK());
    }

    @GetMapping("/edit")
    protected void edit(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Integer fid = Integer.parseInt(req.getParameter("fid"));
        Fruit fruit = fruitService.getFruitById(fid);
        ResponseUtil.print(resp, Result.OK(fruit));
    }

    @GetMapping("/getFname")
    public void getFname(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {


        String fname = req.getParameter("fname");
        Fruit fruit = fruitService.getFruitByFname(fname);
        ResponseUtil.print(resp, fruit == null ? Result.OK() : Result.Fail());
    }

    @PostMapping("/update")
    protected void update(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Fruit fruit = (Fruit) RequestUtil.readObject(req, Fruit.class);
        fruitService.updateFruit(fruit);
        ResponseUtil.print(resp, Result.OK());
    }
}

 5、DispatcherServlet

package com.csdn.mymvc.core;
import jakarta.servlet.RequestDispatcher;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;
@WebServlet("/*")
public class DispatcherServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String[] staticResourceSuffixes = {".html", ".jsp", ".jpg", ".png", ".gif", ".css", ".js", ".ico"};
        String uri = req.getRequestURI();
        if (Arrays.stream(staticResourceSuffixes).anyMatch(uri::endsWith)) {
            RequestDispatcher defaultDispatcher = req.getServletContext().getNamedDispatcher("default");
            defaultDispatcher.forward(req,resp);
        }
    }
}