/**

  * 敏感词汇过滤器

  */

 @WebFilter("/*")

 public class SensitiveWordsFilter implements Filter {

     public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {

         //1.创建代理对象，增强getParameter方法

         ServletRequest proxy_req = (ServletRequest) Proxy.newProxyInstance(req.getClass().getClassLoader(), req.getClass().getInterfaces(), new InvocationHandler() {

             @Override

             public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

                 //增强getParameter方法

                 //判断是否是getParameter方法

                 if(method.getName().equals("getParameter")){

                     //增强返回值

                     //获取返回值

                     String value = (String) method.invoke(req,args);

                     if(value != null){

                         for (String str : list) {

                             if(value.contains(str)){

                                 value = value.replaceAll(str,"***");

                             }

                         }

                     }

                     return  value;

                 }

                 //判断方法名是否是 getParameterMap

                 //判断方法名是否是 getParameterValues

                 return method.invoke(req,args);

             }

         });

         //2.放行

         chain.doFilter(proxy_req, resp);

     }

     private List<String> list = new ArrayList<String>();//敏感词汇集合

     public void init(FilterConfig config) throws ServletException {

         try{

             //1.获取文件真实路径

             ServletContext servletContext = config.getServletContext();

             String realPath = servletContext.getRealPath("/WEB-INF/classes/敏感词汇.txt");　　// 敏感词汇.txt在src目录下

             //2.读取文件

             BufferedReader br = new BufferedReader(new FileReader(realPath));

             //3.将文件的每一行数据添加到list中

             String line = null;

             while((line = br.readLine())!=null){

                 list.add(line);

             }

             br.close();

             System.out.println(list);

         }catch (Exception e){

             e.printStackTrace();

         }

     }

     public void destroy() {

     }

 }