Filter

/**
 * 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() {
    }

}