求救！帮忙看看这个问题怎么解决，谢了.

Question

safe.ce.struts.filters.CeEncodingFilter.doFilter(CeEncodingFilter.java:36) 
这个filter是你自己写的吗？

Answer 1

这个filter是这样的，帮我分析有什么问题：
package safe.ce.struts.filters;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;public class CeEncodingFilter implements Filter {
protected String encoding = null;
public void init(FilterConfig config) throws ServletException {
this.encoding = config.getInitParameter("encoding");
}
public void doFilter(ServletRequest req,ServletResponse res,FilterChain chain) 
        throws IOException, ServletException {
HttpServletRequest _req = (HttpServletRequest)req;
req.setCharacterEncoding(this.encoding);
chain.doFilter(req, res);
}
public void destroy() {
this.encoding = null;
}
}