常用过滤器

作者：小蓝xlanll | 2024-03-08 00:30:14

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写出函数最常用的过滤器

复制粘贴！出自：http://xxtianxiaxing.iteye.com/blog/35016
Java代码

   1. 五个有用的过滤器
   2.
   3. 一、使浏览器不缓存页面的过滤器
   4. import javax.servlet.*;
   5. import javax.servlet.http.HttpServletResponse;
   6. import java.io.IOException;
   7.
   8. /**
   9. * 用于的使 Browser 不缓存页面的过滤器
10. */
11. public class ForceNoCacheFilter implements Filter {
12.
13. public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException
14. {
15.     ((HttpServletResponse) response).setHeader("Cache-Control","no-cache");
16.     ((HttpServletResponse) response).setHeader("Pragma","no-cache");
17.     ((HttpServletResponse) response).setDateHeader ("Expires", -1);
18.     filterChain.doFilter(request, response);
19. }
20.
21. public void destroy()
22. {
23. }
24.
25.      public void init(FilterConfig filterConfig) throws ServletException
26. {
27. }
28. }
29.
30. 二、检测用户是否登陆的过滤器
31.
32. import javax.servlet.*;
33. import javax.servlet.http.HttpServletRequest;
34. import javax.servlet.http.HttpServletResponse;
35. import javax.servlet.http.HttpSession;
36. import java.util.List;
37. import java.util.ArrayList;
38. import java.util.StringTokenizer;
39. import java.io.IOException;
40.
41. /**
42. * 用于检测用户是否登陆的过滤器，如果未登录，则重定向到指的登录页面
43.
44.
45. * 配置参数
46.
47.
48. * checkSessionKey 需检查的在 Session 中保存的关键字
49.
50. * redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath
51.
52. * notCheckURLList 不做检查的URL列表，以分号分开，并且 URL 中不包括 ContextPath
53.
54. */
55. public class CheckLoginFilter
56. implements Filter
57. {
58.      protected FilterConfig filterConfig = null;
59.      private String redirectURL = null;
60.      private List notCheckURLList = new ArrayList();
61.      private String sessionKey = null;
62.
63. public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
64. {
65.     HttpServletRequest request = (HttpServletRequest) servletRequest;
66.     HttpServletResponse response = (HttpServletResponse) servletResponse;
67.
68.      HttpSession session = request.getSession();
69.    if(sessionKey == null)
70.     {
71.      filterChain.doFilter(request, response);
72.     return;
73.     }
74.    if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)
75.     {
76.      response.sendRedirect(request.getContextPath() + redirectURL);
77.     return;
78.     }
79.     filterChain.doFilter(servletRequest, servletResponse);
80. }
81.
82. public void destroy()
83. {
84.     notCheckURLList.clear();
85. }
86.
87. private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)
88. {
89.     String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());
90.    return notCheckURLList.contains(uri);
91. }
92.
93. public void init(FilterConfig filterConfig) throws ServletException
94. {
95.    this.filterConfig = filterConfig;
96.     redirectURL = filterConfig.getInitParameter("redirectURL");
97.     sessionKey = filterConfig.getInitParameter("checkSessionKey");
98.
99.     String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");
100.
101.    if(notCheckURLListStr != null)
102.     {
103.      StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");
104.      notCheckURLList.clear();
105.     while(st.hasMoreTokens())
106.      {
107.       notCheckURLList.add(st.nextToken());
108.      }
109.     }
110. }
111. }
112.
113. 三、字符编码的过滤器
114.
115. import javax.servlet.*;
116. import java.io.IOException;
117.
118. /**
119. * 用于设置 HTTP 请求字符编码的过滤器，通过过滤器参数encoding指明使用何种字符编码,用于处理Html Form请求参数的中文问题
120. */
121. public class CharacterEncodingFilter
122. implements Filter
123. {
124. protected FilterConfig filterConfig = null;
125. protected String encoding = "";
126.
127. public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
128. {
129.          if(encoding != null)
130.            servletRequest.setCharacterEncoding(encoding);
131.           filterChain.doFilter(servletRequest, servletResponse);
132. }
133.
134. public void destroy()
135. {
136.     filterConfig = null;
137.     encoding = null;
138. }
139.
140.      public void init(FilterConfig filterConfig) throws ServletException
141. {
142.           this.filterConfig = filterConfig;
143.          this.encoding = filterConfig.getInitParameter("encoding");
144.
145. }
146. }
147.
148. 四、资源保护过滤器
149.
150.
151. package catalog.view.util;
152.
153. import javax.servlet.Filter;
154. import javax.servlet.FilterConfig;
155. import javax.servlet.ServletRequest;
156. import javax.servlet.ServletResponse;
157. import javax.servlet.FilterChain;
158. import javax.servlet.ServletException;
159. import javax.servlet.http.HttpServletRequest;
160. import java.io.IOException;
161. import java.util.Iterator;
162. import java.util.Set;
163. import java.util.HashSet;
164. //
165. import org.apache.commons.logging.Log;
166. import org.apache.commons.logging.LogFactory;
167.
168. /**
169. * This Filter class handle the security of the application.
170. *
171. * It should be configured inside the web.xml.
172. *
173. * @author Derek Y. Shen
174. */
175. public class SecurityFilter implements Filter {
176. //the login page uri
177. private static final String LOGIN_PAGE_URI = "login.jsf";
178.
179. //the logger object
180. private Log logger = LogFactory.getLog(this.getClass());
181.
182. //a set of restricted resources
183. private Set restrictedResources;
184.
185. /**
186.    * Initializes the Filter.
187.    */
188. public void init(FilterConfig filterConfig) throws ServletException {
189.   this.restrictedResources = new HashSet();
190.   this.restrictedResources.add("/createProduct.jsf");
191.   this.restrictedResources.add("/editProduct.jsf");
192.   this.restrictedResources.add("/productList.jsf");
193. }
194.
195. /**
196.    * Standard doFilter object.
197.    */
198. public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
199.    throws IOException, ServletException {
200.   this.logger.debug("doFilter");
201.
202.    String contextPath = ((HttpServletRequest)req).getContextPath();
203.    String requestUri = ((HttpServletRequest)req).getRequestURI();
204.
205.   this.logger.debug("contextPath = " + contextPath);
206.   this.logger.debug("requestUri = " + requestUri);
207.
208.   if (this.contains(requestUri, contextPath) && !this.authorize((HttpServletRequest)req)) {
209.    this.logger.debug("authorization failed");
210.     ((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req, res);
211.    }
212.   else {
213.    this.logger.debug("authorization succeeded");
214.     chain.doFilter(req, res);
215.    }
216. }
217.
218. public void destroy() {}
219.
220. private boolean contains(String value, String contextPath) {
221.    Iterator ite = this.restrictedResources.iterator();
222.
223.   while (ite.hasNext()) {
224.     String restrictedResource = (String)ite.next();
225.
226.    if ((contextPath + restrictedResource).equalsIgnoreCase(value)) {
227.     return true;
228.     }
229.    }
230.
231.   return false;
232. }
233.
234. private boolean authorize(HttpServletRequest req) {
235.
236.               //处理用户登录
237.        /* UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);
238.
239.    if (user != null && user.getLoggedIn()) {
240.     //user logged in
241.     return true;
242.    }
243.    else {
244.     return false;
245.    }*/
246. }
247. }
248. 五利用Filter限制用户浏览权限
249.
250. 在一个系统中通常有多个权限的用户。不同权限用户的可以浏览不同的页面。使用Filter进行判断不仅省下了代码量，而且如果要更改的话只需要在Filter文件里动下就可以。
251. 以下是Filter文件代码：
252.
253.
254. import java.io.IOException;
255.
256.
257. import javax.servlet.Filter;
258. import javax.servlet.FilterChain;
259. import javax.servlet.FilterConfig;
260. import javax.servlet.ServletException;
261. import javax.servlet.ServletRequest;
262. import javax.servlet.ServletResponse;
263. import javax.servlet.http.HttpServletRequest;
264.
265. public class RightFilter implements Filter {
266.
267.     public void destroy() {
268.
269.      }
270.
271.     public void doFilter(ServletRequest sreq, ServletResponse sres, FilterChain arg2) throws IOException, ServletException {
272.         // 获取uri地址
273.          HttpServletRequest request=(HttpServletRequest)sreq;
274.          String uri = request.getRequestURI();
275.          String ctx=request.getContextPath();
276.          uri = uri.substring(ctx.length());
277.         //判断admin级别网页的浏览权限
278.         if(uri.startsWith("/admin")) {
279.             if(request.getSession().getAttribute("admin")==null) {
280.                  request.setAttribute("message","您没有这个权限");
281.                  request.getRequestDispatcher("/login.jsp").forward(sreq,sres);
282.                 return;
283.              }
284.          }
285.         //判断manage级别网页的浏览权限
286.         if(uri.startsWith("/manage")) {
287.             //这里省去
288.              }
289.          }
290.         //下面还可以添加其他的用户权限，省去。
291.
292.      }
293.
294.     public void init(FilterConfig arg0) throws ServletException {
295.
296.      }
297.
298. }
299.
300. 
301.   <filter>
302.      <filter-name>RightFilter</filter-name>
303.       <filter-class>cn.itkui.filter.RightFilter</filter-class>
304.   </filter>
305.   <filter-mapping>
306.       <filter-name>RightFilter</filter-name>
307.       <url-pattern>/admin/*</url-pattern>
308.   </filter-mapping>
309.   <filter-mapping>
310.       <filter-name>RightFilter</filter-name>
311.       <url-pattern>/manage/*</url-pattern>
312.   </filter-mapping>
313.
314. 在web.xml中加入Filter的配置，如下：
315. <filter>
316.
317.         <filter-name>EncodingAndCacheflush</filter-name>
318.         <filter-class>EncodingAndCacheflush</filter-class>
319.         <init-param>
320.             <param-name>encoding</param-name>
321.             <param-value>UTF-8</param-value>
322.         </init-param>
323.     </filter>
324.     <filter-mapping>
325.         <filter-name>EncodingAndCacheflush</filter-name>
326.         <url-pattern>/*</url-pattern>
327.     </filter-mapping>
328. 要传递参数的时候最好使用form进行传参，如果使用链接的话当中文字符的时候过滤器转码是不会起作用的，还有就是页面上
329.
330. form的method也要设置为post，不然过滤器也起不了作用。

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