Spring AOP与log4j做简单的异常日志处理
1.在网上看了不少例子，下面自己实践了一下。由于系统开发的时候忘记了对异常的日志处理，所以现在考虑加上，经过考虑决定使用spring的aop与log4j来做，这样做的好处就是我不用在每个类里面try{}catch或者抛出异常。因为类已经写了好多好多了。要是一个一个弄工作量是很大的
。
下面说下简单的实现过程，首先啊，在项目工程中的src目录中加入log4j.properties,内容如下：
###设置日志级别###
###这部分是将info信息输出到控制台###
log4j.rootLogger = info,stdout,F
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %d{ABSOLUTE} %5p %c{1}:%L - %m%n
###错误日志配置###
log4j.appender.F = org.apache.log4j.DailyRollingFileAppender
##输出格式为自定义的HTML##
log4j.appender.F.layout = com.yale.sys.log.FormatHTMLLayout
log4j.appender.F.Threshold = ERROR
log4j.appender.F.Append=true
##错误文件存放位置##
log4j.appender.F.File=error.html
##每天滚动一次文件，即每天产生一个新的文件，文件名字eg：error.html.2012-06-18.html##
log4j.appender.F.DatePattern='.'yyyy-MM-dd'.html'
-------------------------------耐心的看下去
-----------------------------------
其次呢，看上面红色那部分，因为是要将输出日志信息存储到html文件中，所以重写了下log4j中HTMLLayout类,代码片段：
package com.yale.sys.log;import java.text.SimpleDateFormat;import org.apache.log4j.HTMLLayout;import org.apache.log4j.Layout;import org.apache.log4j.Level;import org.apache.log4j.helpers.Transform;import org.apache.log4j.spi.LocationInfo;import org.apache.log4j.spi.LoggingEvent;/** * log4j输出到html格式重写 * @author yale * */public class FormatHTMLLayout extends HTMLLayout { public FormatHTMLLayout() { } [/size] protected final int BUF_SIZE = 256; protected final int MAX_CAPACITY = 1024; static String TRACE_PREFIX = "<br> "; // output buffer appended to when format() is invoked private StringBuffer sbuf = new StringBuffer(BUF_SIZE); String title="系统错误日志"; /** * A string constant used in naming the option for setting the the HTML * document title. Current value of this string constant is <b>Title</b>. */ public static final String TITLE_OPTION = "Title"; // Print no location info by default boolean locationInfo = true; public String format(LoggingEvent event) { if (sbuf.capacity() > MAX_CAPACITY) { sbuf = new StringBuffer(BUF_SIZE); } else { sbuf.setLength(0); } sbuf.append(Layout.LINE_SEP + "<tr>" + Layout.LINE_SEP); sbuf.append("<td>"); sbuf.append(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new java.util.Date())); sbuf.append("</td>" + Layout.LINE_SEP); sbuf.append("<td title=\"级别\">"); if (event.getLevel().equals(Level.FATAL)) { sbuf.append("<font color=\"#339933\">"); sbuf.append(Transform.escapeTags(String.valueOf(event.getLevel()))); sbuf.append("</font>"); } else if (event.getLevel().isGreaterOrEqual(Level.WARN)) { sbuf.append("<font color=\"#993300\"><strong>"); sbuf.append(Transform.escapeTags(String.valueOf(event.getLevel()))); sbuf.append("</strong></font>"); } else { sbuf.append("<font color=\"green\">"); sbuf.append(Transform.escapeTags(String.valueOf(event.getLevel()))); sbuf.append("</font>"); } sbuf.append("</td>" + Layout.LINE_SEP); if (locationInfo) { LocationInfo locInfo = event.getLocationInformation(); sbuf.append("<td title=\"错误\">"); sbuf.append("<font color=\"red\">"); sbuf.append(Transform.escapeTags(locInfo.getFileName())); sbuf.append(':'); sbuf.append(locInfo.getMethodName()).append("()方法中第"); sbuf.append(locInfo.getLineNumber()).append("行出现错误"); sbuf.append("</font>"); sbuf.append("</td>" + Layout.LINE_SEP); } sbuf.append("<td title=\"错误信息\">"); sbuf.append(Transform.escapeTags(event.getRenderedMessage())); sbuf.append("</td>" + Layout.LINE_SEP); sbuf.append("</tr>" + Layout.LINE_SEP); if (event.getNDC() != null) { sbuf.append("<tr><td bgcolor=\"#EEEEEE\" style=\"font-size : xx-small;\" colspan=\"6\" title=\"Nested Diagnostic Context\">"); sbuf.append("NDC: " + Transform.escapeTags(event.getNDC())); sbuf.append("</td></tr>" + Layout.LINE_SEP); } String[] s = event.getThrowableStrRep(); if (s != null) { sbuf.append("<tr><td bgcolor=\"#993300\" style=\"color:White; font-size : xx-small;\" colspan=\"4\">"); appendThrowableAsHTML(s, sbuf); sbuf.append("</td></tr>" + Layout.LINE_SEP); } return sbuf.toString(); } private void appendThrowableAsHTML(String[] s, StringBuffer sbuf) { if (s != null) { int len = s.length; if (len == 0) return; sbuf.append(Transform.escapeTags(s[0])); sbuf.append(Layout.LINE_SEP); for (int i = 1; i < len; i++) { sbuf.append(TRACE_PREFIX); sbuf.append(Transform.escapeTags(s[i])); sbuf.append(Layout.LINE_SEP); } } } /** * Returns appropriate HTML headers. */ public String getHeader() { sbuf.append("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">" + Layout.LINE_SEP); sbuf.append("<html>" + Layout.LINE_SEP); sbuf.append("<head>" + Layout.LINE_SEP); sbuf.append("<title>" + title + "</title>" + Layout.LINE_SEP); sbuf.append("<style type=\"text/css\">" + Layout.LINE_SEP); sbuf.append("<!--" + Layout.LINE_SEP); sbuf.append("body, table {font-family: '宋体',arial,sans-serif; font-size: 12px;}" + Layout.LINE_SEP); sbuf.append("th {background: #336699; color: #FFFFFF; text-align: left;}" + Layout.LINE_SEP); sbuf.append("-->" + Layout.LINE_SEP); sbuf.append("</style>" + Layout.LINE_SEP); sbuf.append("</head>" + Layout.LINE_SEP); sbuf.append("<body bgcolor=\"#FFFFFF\" topmargin=\"6\" leftmargin=\"6\">" + Layout.LINE_SEP); sbuf.append("<table cellspacing=\"0\" cellpadding=\"4\" border=\"1\" bordercolor=\"#224466\" width=\"100%\">" + Layout.LINE_SEP); sbuf.append("<tr>" + Layout.LINE_SEP); sbuf.append("<th>执行时间</th>" + Layout.LINE_SEP); sbuf.append("<th>级别</th>" + Layout.LINE_SEP); if (locationInfo) { sbuf.append("<th>所在行</th>" + Layout.LINE_SEP); } sbuf.append("<th>错误信息</th>" + Layout.LINE_SEP); sbuf.append("</tr>" + Layout.LINE_SEP); sbuf.append("<br></br>" + Layout.LINE_SEP); return sbuf.toString(); } } ----------------------------耐心点往下看，就要没了
--------------------------------------------------再来就是错误文件error.html的存储位置，想要放在项目的WebRoot下，于是就写了个servlet，代码片段：
package com.yale.sys.log;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.util.Properties;import javax.servlet.Servlet;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import org.apache.log4j.PropertyConfigurator;/** * 初始化日志错误文件存放的路径 */public class LogFileSavePathServlet extends HttpServlet {private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public LogFileSavePathServlet() { super(); // TODO Auto-generated constructor stub }/** * @see Servlet#init(ServletConfig) */public void init() throws ServletException {//获得系统的路径 /WebRoot String rootPath = this.getServletContext().getRealPath("/"); //获得log4j.properties的输入流 InputStream is =this.getClass().getClassLoader().getResourceAsStream("log4j.properties"); Properties prop = new Properties(); try {prop.load(is);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} //设置日志文件的输出路径 prop.setProperty("log4j.appender.F.File",rootPath+prop.getProperty("log4j.appender.F.File"));prop.setProperty("log4j.appender.F.DatePattern",rootPath+prop.getProperty("log4j.appender.F.DatePattern"));//加载配置项 PropertyConfigurator.configure(prop); super.init();}}注意啦，错误文件存储的路径不允许空格上面乱码七糟的，一定要注意哦。
写完这个servlet，我们不能忘记初始化，您说对不对啊，所以啊,web.xml就像下面这个样子了：
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" ><web-app><!-- 日志文件存储路径初始化--> <servlet> <servlet-name>LogFileSavePathServlet</servlet-name> <display-name>LogFileSavePathServlet</display-name> <description></description> <servlet-class>com.peoplespot.sys.log.LogFileSavePathServlet</servlet-class> <load-on-startup>0</load-on-startup> </servlet> <servlet-mapping> <servlet-name>LogFileSavePathServlet</servlet-name> <url-pattern>/LogFileSavePathServlet</url-pattern> </servlet-mapping></web-app>
--------------------------------下面就开始和spring aop相关啦，看吧，看吧-----------------------
再一次首先，写一个系统异常日志拦截器类，您看：
package com.yale.sys.log;import org.apache.log4j.Logger;import org.aspectj.lang.ProceedingJoinPoint;/** * 系统异常日志拦截器 * @author yale * */public class LogInterceptor { static Logger logger = Logger.getLogger(LogInterceptor.class); public Object invoke(ProceedingJoinPoint joinPoint) throws Throwable { StringBuffer sb = new StringBuffer(); try{ Object result = joinPoint.proceed(); return result; }catch(Exception e){ sb.append("开始方法："+joinPoint.getTarget().getClass() + "." + joinPoint.getSignature().getName()+ "() "); sb.append("错误信息如下：["+e.getMessage()+"]"); logger.error(sb.toString()); } return "error";//因为用到了strut2，所以出现异常会返回到<result name="error">/erreo.jsp</result>这个页面中，当然啦，你也可以配置成全局的异常返回页。 } }上面这个类，主要用到了aspectj中的ProceedingJoinPoint，支持的是<aop:around />。
类写完了，但是spring配置文件applicationContext.xml还没有搞啊，所以搞一下：
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd"><!-- 配置日志拦截器 --><bean id="logInterceptor" ref="logInterceptor"><aop:around method="invoke" pointcut="execution(public * com.yale.live.action..*.*(..))" /></aop:aspect><aop:aspect id="logAspectDNA" ref="logInterceptor"><aop:around method="invoke" pointcut="execution(public * com.yale.sys.action..*.*(..))" /></aop:aspect></aop:config></beans>
小插曲：看见<aop:config>节点中proxy-target-/>
启动项目开始运行吧，模拟了下一个异常，输出到html最终这样啦