Created
September 24, 2014 03:05
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使用 Filter实现 FlashAttribute
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| package com.kaishengit.web.filter; | |
| import java.io.IOException; | |
| import java.util.Enumeration; | |
| import java.util.HashMap; | |
| import java.util.Map; | |
| import java.util.Map.Entry; | |
| import javax.servlet.Filter; | |
| import javax.servlet.FilterChain; | |
| import javax.servlet.FilterConfig; | |
| import javax.servlet.ServletException; | |
| import javax.servlet.ServletRequest; | |
| import javax.servlet.ServletResponse; | |
| import javax.servlet.http.HttpServletRequest; | |
| import javax.servlet.http.HttpSession; | |
| public class FlashScopeFilter implements Filter { | |
| private static final String FLASH_SESSION_SCOPE = "flash_session_scope"; | |
| @Override | |
| public void destroy() { | |
| } | |
| @Override | |
| public void doFilter(ServletRequest req, ServletResponse resp, | |
| FilterChain chain) throws IOException, ServletException { | |
| HttpServletRequest request = (HttpServletRequest) req; | |
| HttpSession session = request.getSession(); | |
| System.out.println("before"); | |
| @SuppressWarnings("unchecked") | |
| Map<String, Object> sessionParams = (Map<String, Object>) session.getAttribute(FLASH_SESSION_SCOPE); | |
| if(sessionParams != null) { | |
| for(Entry<String, Object> entry : sessionParams.entrySet()) { | |
| request.setAttribute(entry.getKey(), entry.getValue()); | |
| } | |
| session.removeAttribute(FLASH_SESSION_SCOPE); | |
| } | |
| chain.doFilter(req, resp); | |
| System.out.println("after"); | |
| Map<String, Object> flashParams = new HashMap<String, Object>(); | |
| Enumeration<String> attrNames = request.getAttributeNames(); | |
| while(attrNames.hasMoreElements()) { | |
| String attrName = attrNames.nextElement(); | |
| if(attrName.startsWith("flash.")) { | |
| flashParams.put(attrName.substring(attrName.indexOf(".")+1), request.getAttribute(attrName)); | |
| } | |
| } | |
| if(!flashParams.isEmpty()) { | |
| session.setAttribute(FLASH_SESSION_SCOPE, flashParams); | |
| } | |
| } | |
| @Override | |
| public void init(FilterConfig arg0) throws ServletException { | |
| } | |
| } |
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| <%@ page language="java" contentType="text/html; charset=UTF-8" | |
| pageEncoding="UTF-8"%> | |
| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> | |
| <html> | |
| <head> | |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> | |
| <title>Insert title here</title> | |
| </head> | |
| <body> | |
| 提示消息：${message} | |
| </body> | |
| </html> |
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| @WebServlet("/save.do") | |
| public class SaveServlet extends HttpServlet { | |
| private static final long serialVersionUID = 1L; | |
| protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { | |
| request.getRequestDispatcher("/WEB-INF/views/save.jsp").forward(request, response); | |
| } | |
| protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { | |
| String money = request.getParameter("money"); | |
| //以 flash 开头的都会被传递 | |
| request.setAttribute("flash.message", "支付成功"); | |
| response.sendRedirect("/suc.do"); | |
| } | |
| } |
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