java.lang.NumberFormatException: For input string: ""

log4j中怎样将异常的完整信息写入日志文件？？？？？
log4j中怎样将异常的完整信息写入日志文件？？？？？
比如说，现在出现如下异常：

Java code

java.lang.NumberFormatException: For input string: ""    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)    at java.lang.Integer.parseInt(Integer.java:468)    at java.lang.Integer.parseInt(Integer.java:497)    at qing.log.struts.action.LiuAction.execute(LiuAction.java:44)    at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)    at java.lang.Thread.run(Thread.java:619)

Java code

在log4j.properties文件！log4j.appender.file=org.apache.log4j.FileAppenderlog4j.appender.file.File=D://info.log      //这里设置日志文件输出路径log4j.appender.file.layout=org.apache.log4j.PatternLayoutlog4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %m %nlog4j.rootLogger=DEBUG, file//定义一个类public class LogInfo {    Logger logger = Logger.getLogger(LogInfo.class.getName());/** * 系统管理 */    /**     * @param addmin(String     *            name,String addname)添加管理员     * @param name     *            String     * @param addname     *            String     */    public void addadmin(String name, String addname) {        try {            logger.debug("管理员：" + name + "添加" + addname + "为管理员");        } catch (Exception ex) {            logger.info(ex.getMessage());        }    }    //……各种各样的方法自己定义}
[解决办法]
当发生异常的时候
在catch处调用该方法即可！
new LogInfo().addadmin(u.getUserName(),userName);//记录到日志中
[解决办法]
Java code
/**     * org.apache.log4j.Logger     *      * private static Logger log = Logger.getLogger("在log4j.properties文件中的 appenderName");      * 把log4j.properties 放在src下.     * log4j.properties 包含的内容如下：     * log4j.rootLogger = [priority] , appenderName      -- appenderName 为该日志的名称 ， 可以为多个。     * log4j.appender 为 输出源 指定信息输出的地址： ConsoleAppender为控制台、RollingFileAppender 为文件大小到指定尺寸产生一个新的文件     * log4j.appender.layout 设置 输出源 显示格式.     *      *      *  例如:      *  配置 log4j.properties     *  log4j.rootLogger = ALL,Mylog,R     *  log4j.appender.Mylog = org.apache.log4j.ConsoleAppender      *  log4j.appender.Mylog.layout = org.apache.log4j.PatternLayout     *  log4j.appender.Mylog.layout.conversionPattern = %d %p %c --> %m%n        *       *       *  指定日志文件放的位置     *  log4j.appender.R.File=D:/env/environment/webEnv/WEB-INF/log4j.log      *  log4j.appender.R.MaxFileSize=100KB     *  log4j.appender.R.MaxBackupIndex=1     *  log4j.appender.R.layout=org.apache.log4j.PatternLayout     *  log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n     *  log4j.appender.R.layout.ConversionPattern=%d %-5p [%t] (%13F:%L) %3x - %m%n     * ---------------------------------------     *       *  在程序中:     *  Logger logger = Logger.getLogger("Mylog");     *  PropertyConfigurator.configure("log4j.properties");   -- 自动快速的使用默认Log4j环境     *  logger.debug("");     *  logger.info("");     *  logger.error("");     *  logger.fatal("");     *  logger.warn("");     *       *  那个类使用日志 则参照上面代码即可。     *       *       */ 
 
[解决办法]
调用logger.info(getTrace(e));就可以了
Java code
public String getTrace(Throwable t) {        StringWriter stringWriter= new StringWriter();        PrintWriter writer= new PrintWriter(stringWriter);        t.printStackTrace(writer);        StringBuffer buffer= stringWriter.getBuffer();        return buffer.toString();    }