如何使用过滤器处理Servlet中引发的异常

Question

My purpose is create a Filter to handle the exception that are throwed in the servlet.

Suppose I have this filter:

public class FiltroAccess implements Filter{

    public void destroy() {
        // TODO Auto-generated method stub

    }

    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        //handle exception

    }

    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }
}

and in my servlet I throws the Exception

How can I must do to handle in my filter the Exeception ?

Anyone can help me?

Answer 1

Just enclose the filter chain call in a try/catch block:

public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
        throws IOException, ServletException {
    try {
        arg2.doFilter(arg0, arg1);
    }
    catch (Exception e) {
        // Handle exception here
    }
}

The only problem is that is the ServletResponse has already be committed (sent to the client) you will not be able to change the headers.