模拟实现SpringMVC功能

其他 2020-03-05 10:38:41 阅读次数: 0

SpringMVC

MVC

​ m：model:模型，javabean

​ v：view：视图，html/jsp

​ c：controller：控制器：servlet

MyMVC模拟实现

一. 阶段一

  1. index.html页面

    <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>index</title>
</head>
<body>
    <h1>this is index page.</h1>

    <form method="post" action="ProductServlet">
        pid:<input type="text" name="pid" /><br />
        pname:<input type="text" name="pname" /><br />
        price:<input type="text" name="price" /><br />
        img:<input type="text" name="img" /><br />
        <input type="submit" value="submit" /><br />
    </form>
</body>
</html>

  2. ProductServlet.java

    package com.qfedu.controller;

import com.qfedu.bean.Product;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@javax.servlet.annotation.WebServlet(urlPatterns = "/ProductServlet")
public class ProductServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //System.out.println(123);

        String pid = request.getParameter("pid");
        String pname = request.getParameter("pname");
        String sprice = request.getParameter("price");
        String img = request.getParameter("img");

        double price = sprice == null ? 0.0 : Double.parseDouble(sprice);

        System.out.println("pid : " + pid);
        System.out.println("price : " + sprice);
        System.out.println("pname : " + pname);
        System.out.println("img : " + img);

        Product p = new Product();

        p.setPid(pid);
        p.setPname(pname);
        p.setImg(img);
        p.setPrice(price);

        request.setAttribute("p", p);

        request.getRequestDispatcher("product.jsp").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

  3. Product.jsp

    <%--
  Created by IntelliJ IDEA.
  User: james
  Date: 2020/3/2
  Time: 2:52 PM
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>product</title>
</head>
<body>
    <h1>this is product detail page.</h1>

    <%--
        ognl: 对象导航语言
            user.addr.province;
    --%>
    <h3>pid : ${p.pid}</h3>
    <h3>pname : ${p.pname}</h3>
    <h3>price : ${p.price}</h3>
    <h3>img : ${p.img}</h3>
</body>
</html>

    可以实现页面的跳转以及数据的展示

    问题：页面都在webapp下，安全性不高

    二. 阶段二

    为了提高程序的安全性，将所有的页面都放入webapp/WEB-INF/view目录下，index.html页面无法直接访问，需要专门建立一个Sevlet来访问该页面，实现内容请求转发

    新建一个Servlet来实现内部转发 ProductInputServlet.java

    package com.qfedu.controller;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet(urlPatterns = "/ProductInputServlet")
public class ProductInputServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.getRequestDispatcher("/WEB-INF/view/index.html").forward(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

    webapp下的WEB-INF/view/index.html页面可以直接访问，更新ProductServlet.java

    扫描二维码关注公众号，回复： 9591950 查看本文章 
    package com.qfedu.controller;

import com.qfedu.bean.Product;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@javax.servlet.annotation.WebServlet(urlPatterns = "/ProductServlet")
public class ProductServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //System.out.println(123);

        String pid = request.getParameter("pid");
        String pname = request.getParameter("pname");
        String sprice = request.getParameter("price");
        String img = request.getParameter("img");

        double price = sprice == null ? 0.0 : Double.parseDouble(sprice);

        System.out.println("pid : " + pid);
        System.out.println("price : " + sprice);
        System.out.println("pname : " + pname);
        System.out.println("img : " + img);

        Product p = new Product();

        p.setPid(pid);
        p.setPname(pname);
        p.setImg(img);
        p.setPrice(price);

        request.setAttribute("p", p);

        //request.getRequestDispatcher("product.jsp").forward(request,response);
        request.getRequestDispatcher("/WEB-INF/view/product.jsp").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

    三. 阶段三，模拟Spring MVC的具体实现

    1. Controller.java

      package com.qfedu.mvc.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 自定义接口，实现管理多个请求,在模拟Spring MVC中的控制器
 */
public interface Controller {

    String handleRequest(HttpServletRequest request, HttpServletResponse response);
}

    2. ProductInputController.java

      package com.qfedu.mvc.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ProductInputController implements Controller {
    @Override
    public String handleRequest(HttpServletRequest request, HttpServletResponse response) {
        return "/WEB-INF/view/index.html";
    }
}

    3. ProductDetailController.java

      package com.qfedu.mvc.controller;

import com.qfedu.bean.Product;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ProductDetailController implements Controller {
    @Override
    public String handleRequest(HttpServletRequest request, HttpServletResponse response) {

        String pid = request.getParameter("pid");
        String pname = request.getParameter("pname");
        String sprice = request.getParameter("price");
        String img = request.getParameter("img");

        double price = sprice == null ? 0.0 : Double.parseDouble(sprice);

        System.out.println("pid : " + pid);
        System.out.println("price : " + sprice);
        System.out.println("pname : " + pname);
        System.out.println("img : " + img);

        Product p = new Product();

        p.setPid(pid);
        p.setPname(pname);
        p.setImg(img);
        p.setPrice(price);

        request.setAttribute("p", p);

        return "/WEB-INF/view/product.jsp";
    }
}

    4. DispatcherServlet.java负责将多个请求分发给各自不同的控制器

      package com.qfedu.mvc.controller;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet(urlPatterns = {"/ProductInput", "/ProductDetail"})
public class DispatcherServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String requestURI = request.getRequestURI();
        //System.out.println(requestURI);

        String action = requestURI.substring(requestURI.lastIndexOf("/") + 1);

        //System.out.println(action);

        Controller controller = null;

        if("ProductInput".equalsIgnoreCase(action)){
            controller = new ProductInputController();
        }else if("ProductDetail".equalsIgnoreCase(action)){
            controller = new ProductDetailController();
        }

        String url = controller.handleRequest(request, response);

        request.getRequestDispatcher(url).forward(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

      结论：多个请求可以交给同一个Servlet（DispatcherServlet），然后各自不同的请求会交给各自的控制器。所有请求都叫个DispatcerServet，该角色相当于一个前端控制器，可以大大的提高客户的以及服务器端的工作效率。

      四.阶段四

      给阶段三的功能之上添加一个校验功能

      1. 新增一个ProductForm.java,主要用来做Product校验，struts1有专门的formbean对象用来校验表单数据，在某些框架中将formbean与bean对象合二为一了

        package com.qfedu.form;

public class ProductForm {

    private String pname;
    private double price;
    private String img;

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getImg() {
        return img;
    }

    public void setImg(String img) {
        this.img = img;
    }
}

      2. ProductValidate.java，用来完成对于formbean进行校验，如果校验不通过，则将错误信息存储起来

        package com.qfedu.validate;

import com.qfedu.form.ProductForm;

import java.util.ArrayList;
import java.util.List;

public class ProductValidate {

    /**
     * 校验给定的ProductForm对象
     * @param pf 要校验的对象
     * @return 表单校验不成功，则将错误信息存储
     */
    public List<String> validate(ProductForm pf){
        List<String> errors = null;

        String pname = pf.getPname();
        String img = pf.getImg();
        double price = pf.getPrice();

        errors = new ArrayList<>();

        if(pname == null || pname.length() == 0){
            errors.add("product name must not be empty.");
        }


        if(img == null || img.length() == 0){
            errors.add("product image must not be empty.");
        }

        if(price < 0){
            errors.add("the price of product must be a positive number.");
        }

        return errors;
    }
}

      3. 更新ProductDetailController.java

        package com.qfedu.mvc.controller;

import com.qfedu.ProductValidate;
import com.qfedu.bean.Product;
import com.qfedu.form.ProductForm;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

public class ProductDetailController implements Controller {
    @Override
    public String handleRequest(HttpServletRequest request, HttpServletResponse response) {

        String pid = request.getParameter("pid");
        String pname = request.getParameter("pname");
        String sprice = request.getParameter("price");
        String img = request.getParameter("img");

        double price = sprice == null ? 0.0 : Double.parseDouble(sprice);

        System.out.println("pid : " + pid);
        System.out.println("price : " + sprice);
        System.out.println("pname : " + pname);
        System.out.println("img : " + img);

        ProductForm pf = new ProductForm();

        pf.setImg(img);
        pf.setPname(pname);
        pf.setPrice(price);

        ProductValidate pv = new ProductValidate();

        List<String> errors = pv.validate(pf);

        try {
            if(errors != null && !errors.isEmpty()){
                request.setAttribute("errors", errors);
                return "/WEB-INF/view/index.jsp";
            }else{

                Product p = new Product();

                p.setPid(pid);
                p.setPname(pf.getPname());
                p.setImg(pf.getImg());
                p.setPrice(pf.getPrice());

                request.setAttribute("p", p);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return "/WEB-INF/view/product.jsp";
    }
}

到此我们自定义的MVC框架也就有了校验功能

zpz2001
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