添加Interceptor文件

src/cn/edu/hactcm/interceptor/Loginlnterceptor.java

@@ -0,0 +1,47 @@
+package com.itheima.interceptor;
+
+import com.itheima.po.Admin;
+import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.ModelAndView;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpSession;
+
+/**
+ * 登录拦截器
+ */
+public class Loginlnterceptor implements HandlerInterceptor {
+    @Override
+    public boolean preHandle(HttpServletRequest request,
+                             HttpServletResponse response, Object handler) throws Exception {
+        // 获取请求的URL
+        String url = request.getRequestURI();
+        // URL:除了login.jsp是可以公开访问的，其它的URL都进行拦截控制
+        if(url.indexOf("/login")>=0){
+            return true;
+        }
+        // 获取Session
+        HttpSession session = request.getSession();
+        Admin admin = (Admin) session.getAttribute("admin");
+        // 判断Session中是否有用户数据，如果有，则返回true,继续向下执行
+        if(admin != null){
+            return true;
+        }
+        // 不符合条件的给出提示信息，并转发到主页面
+        request.setAttribute("msga", "您还没有登录，请先登录！");
+        request.getRequestDispatcher("/shopping homepage.jsp")
+                .forward(request, response);
+        return false;
+    }
+    @Override
+    public void postHandle(HttpServletRequest request,
+                           HttpServletResponse response, Object handler,
+                           ModelAndView modelAndView) throws Exception {
+    }
+    @Override
+    public void afterCompletion(HttpServletRequest request,
+                                HttpServletResponse response, Object handler, Exception ex)
+            throws Exception {
+    }
+}