去除危险字符的filter（包含转为中文）

写一个class   :ResponseWappe

package com.xw.servlet;


import java.io.CharArrayWriter;
import java.io.PrintWriter;


import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;


public class ResponseWapper extends HttpServletResponseWrapper {


private CharArrayWriter out;
public ResponseWapper(HttpServletResponse response) {
super(response);
out=new CharArrayWriter();
}
public PrintWriter getWriter()
{   
//new PrintWriter(outputstream)
return new PrintWriter(out);
}


public String toString()
{
return out.toString();
}
}

写filter

package com.xw.servlet;


import java.io.IOException;


import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CharacterFilter implements Filter {
public void destroy() {
  encoding=null;
}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {

HttpServletRequest req=(HttpServletRequest)request;
HttpServletResponse res=(HttpServletResponse)response;
ServletOutputStream outStream=res.getOutputStream();
ResponseWapper wrapper=new ResponseWapper(res);
chain.doFilter(request, wrapper);
/**获取响应内容,此内容为网页中的所有内容，包括网页元代码**
*/
String resStr=wrapper.toString();
String newString="";
if(resStr.indexOf("bad")!=-1)
{
newString=resStr.replace("bad", "**");
outStream.write(newString.getBytes("UTF-8"));
}
else{
outStream.write(resStr.getBytes("UTF-8"));
}
outStream.flush();
outStream.close();

}

       private String encoding=null;
public void init(FilterConfig fConfig) throws ServletException {
      
}


}

配置该filter

<filter>
   <filter-name>CharacterFilter</filter-name>
   <filter-class>com.xw.servlet.CharacterFilter</filter-class>
  
  </filter>
  <filter-mapping>
     <filter-name>CharacterFilter</filter-name>
     <url-pattern>/*</url-pattern>
  </filter-mapping>