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Java Web Application Error Handling solution


1. Create a filter to monitor the request and response.
public class ErrorHandlerFilter implements Filter {

public void init(FilterConfig arg0) throws ServletException {
    }

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {


        ErrorAwareResponseWrapper wrapper = new ErrorAwareResponseWrapper((HttpServletResponse) servletResponse);

        filterChain.doFilter(servletRequest, wrapper);
      
    }

    public void destroy() {
    }
2. A ResponseWrapper to check the error codes if applicable,

public class ErrorAwareResponseWrapper extends HttpServletResponseWrapper{

    public ErrorAwareResponseWrapper(HttpServletResponse httpServletResponse) {
        super(httpServletResponse);
    }
@Override
public void sendError(int errorCode, String msg) throws IOException {
// TODO Auto-generated method stub
 if (errorCode == HttpServletResponse.SC_NOT_FOUND){
           //throw new PageNotFoundException();
 this.sendRedirect("error_404.jsp");
       }else  if (errorCode == HttpServletResponse.SC_INTERNAL_SERVER_ERROR){
        System.out.println("INTERNAL SERVER ERROR OCCURED WITH ERROR AWAREREQUEST WRAPPER"); //I never catch this error actually, struggling ....
                          // some actions to do here
                           .......
                          //
          this.sendRedirect("error_500.jsp");
        }
super.sendError(errorCode, msg);
}
3. Config Web.xml

  <filter>
<filter-name>errorHandlerFilter</filter-name>
<filter-class>com.tantalus.filters.ErrorHandlerFilter</filter-class>
</filter>
<filter-mapping>
     <filter-name>errorHandlerFilter</filter-name>
<url-pattern>/*</url-pattern>
         <!-- These are needed by Tomcat 5 for forwards -->
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</filter-mapping>


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