敏感词替换的留言板试试加filter和不加filter两种做法

最新推荐文章于 2020-04-02 21:11:56 发布

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最新推荐文章于 2020-04-02 21:11:56 发布

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分类专栏：初学jsp servlet 备忘文章标签： filter 表单 servlet jsp

本文链接：https://blog.youkuaiyun.com/u012270113/article/details/17230119

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本文通过实例展示了两种在留言板中实现敏感词过滤的方法：一种是直接在servlet中处理，另一种是使用filter进行过滤。详细步骤包括表单创建、servlet操作以及filter的配置和使用。强调了在使用filter时，需将修改后的字符串重新传给request对象以确保效果。

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一不加filter写成的留言板控制敏感词

1.写表单

<body>
    <form action = "commentServlet" method = "post">

    username:<input type = "text" name = "username"><br>
    comment:<textarea name = "comment">
    </textarea><br>
    <input type = "submit">
    </form>
</body>

2.完成action转向的servlet内容

public class commentServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
       throws ServletException, IOException {
    String username = req.getParameter("username");
    String comment = req.getParameter("comment");

   username = username.replace("zhang", "li");
   comment = comment.replace("wjl", "gcd");
   req.setAttribute("username", username);
   req.setAttribute("comment", comment);
   req.getRequestDispatcher("MyJsp.jsp").forward(req, resp);
}
}
3.完成转发的页面

<body>
username: <%=request.getAttribute("username") %><br>
comment:<%= request.getAttribute("comment")%>

</body>

总结：修改过的字符串如果不重新传给request对象，那就白瞎了。

二、加filter写成的留言板控制敏感词

1.写表单不变

2.写filter

public class commentFilter implements Filter {

   public void destroy() {

   }

   public void doFilter(ServletRequest arg0, ServletResponse arg1,
           FilterChain arg2) throws IOException, ServletException {
    HttpServletRequest req = (HttpServletRequest)arg0;
    HttpServletResponse resp = (HttpServletResponse)arg1;

    String username = arg0.getParameter("username");
    String comment = arg0.getParameter("comment");

   username = username.replace("zhang", "li");
   comment = comment.replace("wjl", "gcd");
   arg0.setAttribute("username", username);
   arg0.setAttribute("comment", comment);

   arg2.doFilter(arg0, arg1);

   }

   public void init(FilterConfig arg0) throws ServletException {

   }

}

3.在web.xml配置filter 可以在servlet之前配置。

<filter-name>commentf</filter-name>
<filter-class>com.my.filter.commentFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>commentf</filter-name>
<url-pattern>/commentServlet</url-pattern>
</filter-mapping>

4.写servlet

简单的转向就可以完事了。