一个替换敏感词的filter
一个过滤敏感词的filter,看书学到的,小结之:
原理是将内容输出到response时,response将缓存起来,在filter中替换,然后再输出到客户端浏览器.因为默认的response不能缓存输出内容,
因此要自定义response,可以通过扩展HttpServletResponseWrapper获得,
importjava.io.CharArrayWriter;
importjava.io.IOException;
importjava.io.PrintWriter;
importjavax.servlet.http.HttpServletResponse;
importjavax.servlet.http.HttpServletResponseWrapper;
publicclassHttpCharacterResponseWrapperextendsHttpServletResponseWrapper{
privateCharArrayWritercharArrayWriter=newCharArrayWriter();
publicHttpCharacterResponseWrapper(HttpServletResponseresponse){
super(response);
}
@Override
publicPrintWritergetWriter()throwsIOException{
returnnewPrintWriter(charArrayWriter);
}
publicCharArrayWritergetCharArrayWriter(){
returncharArrayWriter;
}
}
filter需要将自定义的response传到servlet中,代码如下:
publicclassOutputReplaceFilterimplementsFilter{
privatePropertiespp=newProperties();
publicvoidinit(FilterConfigconfig)throwsServletException{
Stringfile=config.getInitParameter("file");
StringrealPath=config.getServletContext().getRealPath(file);
try{
pp.load(newFileInputStream(realPath));
}catch(IOExceptione){
}
}
publicvoiddoFilter(ServletRequestreq,ServletResponseres,
FilterChainchain)throwsIOException,ServletException{
//自定义的response
HttpCharacterResponseWrapperresponse=newHttpCharacterResponseWrapper(
(HttpServletResponse)res);
//提交给Servlet或者下一个Filter
chain.doFilter(req,response);
//得到缓存在自定义response中的输出内容
Stringoutput=response.getCharArrayWriter().toString();
//修改，替换
for(Objectobj:pp.keySet()){
Stringkey=(String)obj;
output=output.replace(key,pp.getProperty(key));
}
//输出
PrintWriterout=res.getWriter();
out.write(output);
out.println("<!--Generatedat"+newjava.util.Date()+"-->");
}
publicvoiddestroy(){
}