struts2捕捉到异常不打log的处理方法

　　项目里用到struts2，经常出现Action出现异常，但日志文件不打印log。导致问题很难排查。
      解决办法，在项目中加一个过滤器：

　　

package com.whty.eop.cms.common.filter;

/**
 * 
 */

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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * @author zhangchao
 * 
 */
public class ErrorLogFilter implements Filter {

    private static final Log log = LogFactory.getLog(ErrorLogFilter.class);

    /*
     * (non-Javadoc)
     * 
     * @see javax.servlet.Filter#destroy()
     */
    @Override
    public void destroy() {
        log.info("Exception Log Filter destroy");

    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
     * javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        try {
            chain.doFilter(request, response);
            // 因为struts2捕捉到异常以后就把异常放到request的javax.servlet.error.exception属性里面，
            // 不打印log，所以最好截获一下异常，把log打印出来
            Object exception = request
                    .getAttribute("javax.servlet.error.exception");
            if (exception != null && exception instanceof Exception) {
                log.error("Server Intenal Exception", (Exception) exception);
            }

        } catch (Exception ex) {
            log.error("Server Intenal Exception", ex);
            throw new ServletException(ex);
        }

    }

    /*
     * (non-Javadoc)
     * 
     * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
     */
    @Override
    public void init(FilterConfig arg0) throws ServletException {
        log.info("Exception Log Filter Init");

    }

}

web.xml中增加配置：

　　<filter>
        <filter-name>errorLogFilter</filter-name>
        <filter-class>
            com.whty.common.filter.ErrorLogFilter
        </filter-class>
    </filter>
    <filter-mapping>
        <filter-name>errorLogFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>