javaweb_project/src/com/hua/filter/AcdemicDeanJspFilter.java

@@ -1,14 +1,14 @@
-package com.hua.filter;
+package com.hua.filter; // 定义包名，存放自定义的过滤器类
 
-import java.io.IOException;
-import javax.servlet.DispatcherType;
-import javax.servlet.FilterChain;
-import javax.servlet.ServletException;
-import javax.servlet.annotation.WebFilter;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import java.io.IOException; // 导入IOException，用于处理IO异常
+import javax.servlet.DispatcherType; // 导入DispatcherType，用于定义过滤器的调度类型
+import javax.servlet.FilterChain; // 导入FilterChain，用于调用过滤器链中的下一个过滤器
+import javax.servlet.ServletException; // 导入ServletException，用于处理servlet异常
+import javax.servlet.annotation.WebFilter; // 导入WebFilter注解，用于声明过滤器
+import javax.servlet.http.HttpServletRequest; // 导入HttpServletRequest，用于处理HTTP请求
+import javax.servlet.http.HttpServletResponse; // 导入HttpServletResponse，用于处理HTTP响应
 
-import com.hua.entity.User;
+import com.hua.entity.User; // 导入User实体类，用于获取用户信息
 
 /**
  * 访问教务员用户下的所有页面的过滤器
@@ -16,29 +16,29 @@ import com.hua.entity.User;
  * @author hua
  *
  */
-@WebFilter(dispatcherTypes = {
-				DispatcherType.REQUEST, 
-				DispatcherType.FORWARD, 
-				DispatcherType.INCLUDE
-		}
-					, urlPatterns = { "/acdemic_dean/*" })
-public class AcdemicDeanJspFilter extends HttpFilter {
+@WebFilter(dispatcherTypes = { // 使用WebFilter注解定义过滤器，指定过滤器的调度类型
+		DispatcherType.REQUEST, // REQUEST类型，处理用户请求
+		DispatcherType.FORWARD, // FORWARD类型，处理请求转发
+		DispatcherType.INCLUDE // INCLUDE类型，处理请求包含
+}
+		, urlPatterns = { "/acdemic_dean/*" }) // 指定过滤器的URL模式，匹配/acdemic_dean/路径下的请求
+public class AcdemicDeanJspFilter extends HttpFilter { // 定义AcdemicDeanJspFilter类，继承自HttpFilter
 
 	@Override
-	public void doFilter(HttpServletRequest request,
-			HttpServletResponse response, FilterChain filterChain)
+	public void doFilter(HttpServletRequest request, // 覆盖doFilter方法，处理请求
+						 HttpServletResponse response, FilterChain filterChain)
 			throws IOException, ServletException {
-		User user = (User) request.getSession().getAttribute("user");
-		
-		if(user == null){
-			String message = "账号已过期，请重新登录";
-			request.getSession().setAttribute("message", message);	
-			//重定向回到登录页面
-			response.sendRedirect(request.getContextPath() + "/login/login.jsp");
+		User user = (User) request.getSession().getAttribute("user"); // 从session中获取user对象
+
+		if(user == null){ // 如果user对象为null，说明用户未登录或会话已过期
+			String message = "账号已过期，请重新登录"; // 设置提示信息
+			request.getSession().setAttribute("message", message); // 将提示信息放入session中
+			// 重定向回到登录页面
+			response.sendRedirect(request.getContextPath() + "/login/login.jsp"); // 获取上下文路径并重定向到登录页面
 		}
-		
-		filterChain.doFilter(request, response);
+
+		filterChain.doFilter(request, response); // 如果用户已登录，继续执行过滤器链中的下一个过滤器
 	}
 
-    
-}
+
+}