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    <filter>

           <filter-name>errorHandler</filter-name>

           <filter-class>com.test.ErrorHandler</filter-class>

    </filter>

    <filter-mapping>

           <filter-name>errorHandler</filter-name>

           <url-pattern>*</url-pattern>

    </filter-mapping>

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.HttpServletResponse;



import org.apache.log4j.Logger;

import org.codehaus.jackson.map.ObjectMapper;



// my exception class

import com.test.exception.CustomException;



public class ErrorHandler implements Filter {



        private static final String UTF_8 = "UTF-8";

        private static final String APPLICATION_JSON = "application/json";

        private static final Logger S_LOGGER= Logger.getLogger(ErrorHandler.class);

        private static boolean isDebugEnabled = S_LOGGER.isDebugEnabled();

        

        @Override

        public void init(FilterConfig filterConfig) throws ServletException {

        }



        @Override

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

                try {

                        chain.doFilter(request, response);

                } catch (Exception e) {

                        if (isDebugEnabled) {

                                S_LOGGER.debug("Entering into the catch of ErrorHandler.doFilter()");

                        }

                        CustomException customException = new CustomException(e);

                        

                        ResponseInfo<Object> responseData = new ResponseInfo<Object>();

                        // Here construct the final response object - This is the custome method to construct a java object which will be a response

                        ResponseInfo<Object> finalOuptut = responseDataConstruct(responseData, customException, RESPONSE_STATUS_ERROR, ERR_CODE_000000);

                        

                        ObjectMapper mapper = new ObjectMapper();

                        // Convert it as Strng to return

                        String objectToReturn = mapper.writeValueAsString(finalOuptut);

                        

                        // It returns the json with data or error

                        HttpServletResponse res = (HttpServletResponse)response;

                        res.setStatus(res.SC_OK);

                        

                        response.setContentType(APPLICATION_JSON);

                        response.setCharacterEncoding(UTF_8);

                        PrintWriter out = response.getWriter();

                        out.print(objectToReturn);

                        out.flush();

                }

        }



        @Override

        public void destroy() {

        }

}