catalogservlet.java

Java项目案例导航源代码

package examples;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.naming.*;

/**
 * 本servlet向客户展示图书目录
 */
public class CatalogServlet extends HttpServlet {

	private CatalogHome catalogHome = null;

	/**
	 * 初始化servlet实例
	 */
	public void init(ServletConfig config) throws ServletException {

		super.init(config);

		try {
			/*
			 * 获取并记录部署信息
			 */
			String initCtxFactory = getInitParameter(Context.INITIAL_CONTEXT_FACTORY);
			String providerURL = getInitParameter(Context.PROVIDER_URL);

			Properties env = new Properties();
			env.put(Context.INITIAL_CONTEXT_FACTORY, initCtxFactory);
			env.put(Context.PROVIDER_URL, providerURL);

			/*
			 * 获取初始的JNDI上下文
			 */
			Context ctx = new InitialContext(env);

			/*
			 * 查找Home对象
			 */
			catalogHome = (CatalogHome ) ctx.lookup("CatalogHome");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * 回应客户端的HTTP请求
	 */
	public void service (HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
        Vector	books=null;
		try {

			/*
			 * 获取客户的HttpSession和所用的购书车
			 */
			HttpSession session = request.getSession(false);
			if (session == null) {
				/*
				 * 如果和客户的会话不存在
				 * 则把他重定向到登录界面
				 */
				response.sendRedirect(response.encodeRedirectURL("/BookStore/login"));
				return;
			}

			Object obj = session.getAttribute("cart");
			if (obj == null) {
				/*
				 * 如果和客户的会话不存在
				 * 则把他重定向到登录界面
				 */
				response.sendRedirect(response.encodeRedirectURL("/BookStore/login"));
				return;
			}
			Cart cart = (Cart) obj;
			String bookIDToAdd = request.getParameter("Buy");
			books=(Vector)session.getAttribute("books");
			String bookId=(String)request.getParameter("bookId");  			

			/*
			 * 客户点击'购买'
			 */
			
			if (bookIDToAdd != null) {
                
            /*
             * 把书加入购书车
             */
			try {
                BookItem item=getBookItem(books,bookIDToAdd);
                cart.add(new LineItem(item,1,0));
                // 设置购买标记
                request.setAttribute("BookPurchased", item.getName());
                // 把购买请求转发给catalog JSP
                this.getServletContext().getRequestDispatcher("/catalog.jsp").forward(request, response);
                return;
			} catch (Exception e) {
                throw new ServletException(e.toString());
            }                                
			}
            /*
			 * 客户点击'察看图书细节'
			 */
            else if(bookId!=null){
                //查出图书信息并发送给请求对象
                request.setAttribute("bookItem",getBookItem(books,bookId));
                this.getServletContext().getRequestDispatcher("/bookInfo.jsp").forward(request, response);
                return;
    		}
            else {
                if(books==null){
                    Catalog catalog=catalogHome.create();
                  	books=catalog.getBookItemList();
                  	session.setAttribute("books", books);
                }	
                // 转发请求至 catalog JSP
                this.getServletContext().getRequestDispatcher("/catalog.jsp").forward(request, response);
                return;
			}
		}
		catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 返回代表给定的某本图书的 Bookitem 
     */
   
    private BookItem getBookItem(Vector books,String bookIDToAdd){
        int size=books.size();
        for(int i=0; i<size; i++){
            BookItem item=(BookItem)books.elementAt(i);
            if(item.getBookID().equals(bookIDToAdd)){
               return item;
            }
       }
       return null;
   }
	public String getServletInfo() {
		return "The Catalog servlet adds books to the user's " +
		"cart and prints the catalog.";

	}
}