java程序中输出console的日志到文本

http://blog.sina.com.cn/s/blog_76a8411a01010u2h.html

首先：当我们引入data-integrationlib文件夹下的所有jar包后 运行java程序要求我们必须引入log4j，由此我们可以确认控制台输出的信息为log4j做的：

程序如下：

public static void main(String[] args) throws Exception{
  KettleEnvironment.init();
  try { 

    JobMeta jobMeta = new JobMeta("E:\BI\sample.kjb", null,null);
   Job job = new Job(null, jobMeta);
   jobMeta.setArguments(new String[]{"aaaaa","bbbbbb"});//传参数
            job.getJobMeta().setInternalKettleVariables(job);

            job.setLogLevel(LogLevel.BASIC);
            // Start the Job, as it is a Thread itself by Kettle.
            job.start();
            job.waitUntilFinished();

            if (job.getResult() != null && job.getResult().getNrErrors() != 0) {
             //Do something here.
            }
            // Now the job task is finished, mark it as finished.
            job.setFinished(true);

            // Cleanup the parameters used by the job. Post that invoke GC.
            jobMeta.eraseParameters();
            job.eraseParameters();
        } catch (Exception e) {
             e.printStackTrace();
        }  

 }

 解决步骤：

1、首先想到查看输出这些日志的来源：Job类

2、通过反编译软件 或者 查看源文件 查看代码 找到：this.log = new LogChannel(this);

3、进入LogChannel找到：  private static LogWriter log = LogWriter.getInstance();

可以看出是单例

4、查看LogWiter的构造方法：

private LogWriter()
  {
    this.pentahoLogger = Logger.getLogger("org.pentaho.di");
    this.pentahoLogger.setAdditivity(false);

    this.pentahoLogger.setLevel(Level.ALL);

    layout = new Log4jKettleLayout();

    boolean consoleAppenderFound = false;
    Enumeration appenders = this.pentahoLogger.getAllAppenders();
    while (appenders.hasMoreElements()) {
      Appender appender = (Appender)appenders.nextElement();
      if ((appender instanceof ConsoleAppender)) {
        consoleAppenderFound = true;
        break;
      }

    }

    if (!consoleAppenderFound) {
      Layout patternLayout = new PatternLayout("%-5p %d{dd-MM HH:mm:ss,SSS} - %m%n");
      ConsoleAppender consoleAppender = new ConsoleAppender(patternLayout);
      consoleAppender.setName("ConsoleAppender:org.pentaho.di");
      this.pentahoLogger.addAppender(consoleAppender);
    }

    LogManager.getLogger("org.apache.commons.vfs").setLevel(Level.WARN);
  }
5、看出 原来 他们是判断有没有控制台输出的，如果没有就加入一个控制台输出的，

log的识别符为：Logger.getLogger("org.pentaho.di");

6、==============================================================

=================================================================

由此，我们可以再我们程序中加入一行代码： 手动的去加入一个FileAppender

在try中第一行加入：

Logger.getLogger("org.pentaho.di").addAppender(new FileAppender(new SimpleLayout(), "E:\logger.log"));

这样我们就可以把console端打印出来的log 直接输入到一个log文件中去了