MVC之Servlet控制器

学习目的是为了知道如何用Servlet实现 MVC，也是从原理上弄清楚SpringMVC。

一、工程目录

功能为用户输入 一个商品的信息，并提交，程序保存商品并展示已经保存的商品的信息。

所有的jsp文件都在WEB-INFO下，因此不能直接访问。

二、程序代码 

• product

封闭了一个商品信息的javaBean .

package app02a.domain;

import java.io.Serializable;

public class Product implements Serializable{
	private static final long serialVersionUID =1L;
	private String name ;
	private String description ;
	private float price ;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	public float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
	}

}

• ProducForm

注意，下面的price 为String 类型。

package app02a.from;

/**
 * ProductForm与html中的from相对应，是后者在服务端的代表。
 * @author lsj
 */
public class ProductForm {
	private String name ;
	private String description ;
	private String price ;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	public String getPrice() {
		return price;
	}
	public void setPrice(String price) {
		this.price = price;
	}

}

• 控制部分

package app02a.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import app02a.domain.Product;
import app02a.from.ProductForm;

public class ControllerServlet extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		process(req, resp);
	}

	@Override
	protected void doPut(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		process(req, resp);
	}
	private void process(HttpServletRequest request, HttpServletResponse response){
		String uri = request.getRequestURI() ;
		int lastIndex =uri.lastIndexOf("/");
		String action = uri.substring(lastIndex+1) ;
		//execute an action
		if (action.equals("produc_input")){
			//nothing to do
		}else if (action.equals("product_save")) {
			//create form
			ProductForm productForm = new ProductForm();
			productForm.setName(request.getParameter("name"));
			productForm.setDescription(request.getParameter("description"));
			productForm.setPrice(request.getParameter("price"));
			//create model
			Product product = new Product() ;
			product.setName(productForm.getName());
			product.setDescription(productForm.getDescription());
			try {
				product.setPrice(Float.parseFloat(productForm.getPrice()));
			} catch (NumberFormatException e) {
				e.printStackTrace();
			}

			//code to save product in DB 

			//store model in a scope variable for the view
			//放入到了HttpServletRequest中，以便 对应的视图可以访问到
			request.setAttribute("product", product);
		}

		//forward to a view
		String dispatchUrl = null;
		if (action.equals("product_input")){
			dispatchUrl= "/WEB-INFO/jsp/ProductForm.jsp" ;
		}else if (action.equals("product_save")){
			dispatchUrl= "/WEB-INFO/jsp/ProductDetails.jsp" ;
		}
		//RequestDispatcher: Defines an object that receives requests from the client and
		//sends them to any resource (such as a servlet, HTML file, or JSP file) on the server
		if (dispatchUrl!= null){
			RequestDispatcher rd = request.getRequestDispatcher(dispatchUrl) ;
			try {
				rd.forward(request, response);
			} catch (ServletException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}

		}
	}

}