JavaWeb 过滤敏感词汇

            煞笔
制杖
cxk
        

            <
            form 
            action
            ="handlerServlet"
             method
            ="post"
            >
            
        评论：
            <
            textarea 
            name
            ="comment"
             rows
            ="10"
             cols
            ="50"
            ></
            textarea
            >
            <
            button 
            type
            ="submit"
            >提交</button></form>

@WebFilter("/handlerServlet")
publicclass HandlerFilter implements Filter {
    publicvoid destroy() {
    }

    publicvoid doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        //解决中文乱码
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

    　 //jdk动态代理　　
        ClassLoader classLoader = req.getClass().getClassLoader();
        Class<?>[] interfaces = req.getClass().getInterfaces();
        //创建InvocationHandler接口的实例。此处使用匿名内部类来创建
        InvocationHandler invocationHandler = new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                //只增强getParameter()if(method.getName().equals("getParameter")){
                    //调用原有的getParameter()获取参数值
                    String text = (String) method.invoke(req, args);

                    //检查是否有敏感词汇
                    Object obj = req.getServletContext().getAttribute("illegal_word_list");
                    ArrayList<String> list=(ArrayList<String>)obj;
                    for (String word : list){
                        if (text.contains(word)){
                            //用一个*替换一个字符
                            String replac="";
                            for(int i=0;i<word.length();i++){
                                replac+="*";
                            }
                            //替换所有匹配
                            text = text.replaceAll(word, replac);
                        }
                    }

                    return text;
                }

                //如果调用的是getParameter（）,执行到前面的return就结束了，不会执行到此
                //如果调用的不是getParameter()，就调用原方法，不做修改
                Object returnValue=method.invoke(req,args);  //调用目标方法return returnValue;
            }
        };

        //创建req的代理对象
        Object proxyInstance = Proxy.newProxyInstance(classLoader, interfaces, invocationHandler);
        //强转为ServletRequest
        ServletRequest reqProxyInstance = (ServletRequest) proxyInstance;

        //传入req的代理对象        chain.doFilter(reqProxyInstance, resp);
    }

    publicvoid init(FilterConfig config) throws ServletException {
        InputStream is= this.getClass().getResourceAsStream("/illegal_word.txt");
        //因为要readLine()一行一行地读，需要使用BufferedReader流，所以先转换为Reader，再加Buffer
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        ArrayList<String> list=new ArrayList<>();
        String str=null;
        while (true){
            try {
                str=br.readLine();
                if (str!=null)
                    list.add(str);
                elsebreak;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        //放到ServletContext中
        config.getServletContext().setAttribute("illegal_word_list",list);
    }


}    

@WebServlet("/handlerServlet")
publicclass HandlerServlet extends HttpServlet {
    protectedvoid doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String comment = request.getParameter("comment");
        response.getWriter().write(comment);
    }

    protectedvoid doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}