Java 实战项目锤炼之仿天猫网上商城的实现流程

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基础信息操作:
 
public abstract class BaseBackServlet extends HttpServlet {
 
    /* 添加 */
    public abstract String add(HttpServletRequest request, HttpServletResponse response, Page page);
    /* 删除 */
    public abstract String delete(HttpServletRequest request, HttpServletResponse response, Page page);
    /* 更新 */
    public abstract String update(HttpServletRequest request, HttpServletResponse response, Page page);
    /* 修改 */
    public abstract String edit(HttpServletRequest request, HttpServletResponse response, Page page);
    /* 显示 */
    public abstract String list(HttpServletRequest request, HttpServletResponse response, Page page);
 
    protected CategoryDAO categoryDAO = new CategoryDAO();
    protected OrderDAO orderDAO = new OrderDAO();
    protected OrderItemDAO orderItemDAO = new OrderItemDAO();
    protected ProductDAO productDAO = new ProductDAO();
    protected ProductImageDAO productImageDAO = new ProductImageDAO();
    protected PropertyDAO propertyDAO = new PropertyDAO();
    protected PropertyValueDAO propertyValueDAO = new PropertyValueDAO();
    protected ReviewDAO reviewDAO = new ReviewDAO();
    protected UserDAO userDAO = new UserDAO();
 
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try{
            /* 获取分页信息 */
            int start = 0;
            int count = 5;
            try{
                start = Integer.parseInt(req.getParameter("page.start"));
                count = Integer.parseInt(req.getParameter("page.count"));
            } catch(Exception e) {
 
            }
 
            Page page = new Page(start, count);
 
            /* 借助反射，调用对应的方法 */
            String method = (String)req.getAttribute("method");
            Method m = this.getClass().getMethod(method, HttpServletRequest.class, HttpServletResponse.class, Page.class);
            String redirect = m.invoke(this, req, resp, page).toString();
 
            /* 根据方法的返回值，进行相应的客户端、服务端跳转，或仅输出字符串 */
            if(redirect.startsWith("@")){
                resp.sendRedirect(redirect.substring(1));
            } else if(redirect.startsWith("%")){
                resp.getWriter().print(redirect.substring(1));
            } else {
                req.getRequestDispatcher(redirect).forward(req, resp);
            }
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
 
    public InputStream parseUpload(HttpServletRequest request, Map<String, String> params){
        InputStream is = null;
        try{
            DiskFileItemFactory factory = new DiskFileItemFactory();
            ServletFileUpload upload = new ServletFileUpload(factory);
            //设置上传的文件大小限制为10M
            factory.setSizeThreshold(1024 * 1024);
 
            List items = upload.parseRequest(request);
            Iterator iter = items.iterator();
 
            while(iter.hasNext()){
                FileItem item = (FileItem) iter.next();
                if(!item.isFormField()){
                    //获取上传文件的输入流
                    is = item.getInputStream();
                } else {
                    String paramName = item.getFieldName();
                    String paramValue = item.getString();
                    paramValue = new String(paramValue.getBytes("ISO-8859-1"), "UTF-8");
                    params.put(paramName, paramValue);
                }
            }
 
        } catch (FileUploadException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return is;
    }
 
}

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用户信息操作:
 
public class UserServlet extends BaseBackServlet {
 
    @Override
    public String add(HttpServletRequest request, HttpServletResponse response, Page page) {
        System.out.println("调用了 UserServlet add方法");
        return null;
    }
 
    @Override
    public String delete(HttpServletRequest request, HttpServletResponse response, Page page) {
        System.out.println("调用了 UserServlet delete方法");
 
        int id = Integer.parseInt(request.getParameter("id"));
        userDAO.delete(id);
        return "@admin_user_list";
    }
 
    @Override
    public String update(HttpServletRequest request, HttpServletResponse response, Page page) {
        System.out.println("调用了 UserServlet update方法");
 
        Map<String, String> params = new HashMap<>();
        InputStream is = super.parseUpload(request, params);
        System.out.println(params);
 
        int id = Integer.parseInt(params.get("id"));
        String password = params.get("password");
 
        User user = userDAO.get(id);
        user.setPassword(password);
 
        userDAO.update(user);
 
        return "@admin_user_list";
    }
 
    @Override
    public String edit(HttpServletRequest request, HttpServletResponse response, Page page) {
        System.out.println("调用了 UserServlet edit方法");
 
        int id = Integer.parseInt(request.getParameter("id"));
        User u = userDAO.get(id);
 
        request.setAttribute("u", u);
 
        return "admin/editUser.jsp";
    }
 
    @Override
    public String list(HttpServletRequest request, HttpServletResponse response, Page page) {
        System.out.println("调用了 UserServlet list方法");
 
        List<User> us = userDAO.list(page.getStart(), page.getCount());
        int total = userDAO.getTotal();
        page.setTotal(total);
 
        request.setAttribute("us", us);
        request.setAttribute("page", page);
 
        return "admin/listUser.jsp";
    }
}