log4j每天生成一个日期目录，目录下生成指定大小，指定文件个数的日志文件

在系统运行中log4j产生的日志文件都在一个目录里，查看日志的时候有很多的文件很不直观，如果log4j每天都生成一个以日期为目录名的目录，然后把当天的日志放到该目录里。查询日志的时候如果要查哪天的日志就到哪天的日期目录下查询非常直观方便，如下就是重写org.apache.log4j.RollingFileAppender的类

package com.mttang.js.auth.util;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.apache.log4j.RollingFileAppender;
import org.apache.log4j.helpers.CountingQuietWriter;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

//继承log4j的RollingFileAppender类
public class MttangLog4jRollingFileAppender extends RollingFileAppender {
 
   private long nextRollover = 0;
   private static Map<String, BeginFileData> fileMaps = new HashMap<String, BeginFileData>();
   private static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
   // synchronization not necessary since doAppend is alreasy synched 
   public void rollOver() {
  
     File target;
     File file;
     int maxBackupIndexLeng = String.valueOf(maxBackupIndex).length();
     if (qw != null) {
         long size = ((CountingQuietWriter) qw).getCount();
         LogLog.debug("rolling over count=" + size);
         //   if operation fails, do not roll again until
         //      maxFileSize more bytes are written
         nextRollover = size + maxFileSize;
     }
     LogLog.debug("maxBackupIndex="+maxBackupIndex);
    
     String nowDateString = sdf.format(new Date());
     String newFileName = (fileName.indexOf(".") != -1 ? fileName.substring(0, fileName.lastIndexOf(".")) : fileName);
  
     boolean renameSucceeded = true;
     // If maxBackups <= 0, then there is no file renaming to be done.
     if(maxBackupIndex > 0) {
      
       // Delete the oldest file, to keep Windows happy.
       file = new File(newFileName +'.'+nowDateString+'.' +getIndex(maxBackupIndex,maxBackupIndexLeng));
      
       if (file.exists()){
        renameSucceeded = file.delete();
       }
       // Map {(maxBackupIndex - 1), ..., 2, 1} to {maxBackupIndex, ..., 3, 2}
       for (int i = maxBackupIndex - 1; (i >= 1 && renameSucceeded); i--) 
       {  
    file = new File(newFileName +'.'+nowDateString+'.' + getIndex(i,maxBackupIndexLeng));
    if(file.exists()) 
    {
      target = new File(newFileName +'.'+nowDateString+'.' +getIndex(i+1,maxBackupIndexLeng));
      LogLog.debug("Renaming file " + file + " to " + target);
      renameSucceeded = file.renameTo(target);
    }
       }
      
     if(renameSucceeded) {
       BeginFileData beginFileData = fileMaps.get(fileName);
       System.out.println("fileName= "+fileName+"\t beginFileData="+beginFileData);
       //在每天一个日志目录的方式下，检测日期是否变更了，如果变更了就要把变更后的日志文件拷贝到变更后的日期目录下。
       if(newFileName.indexOf(nowDateString) == -1 && beginFileData.getFileName().indexOf("yyyy-MM-dd") != -1){
       newFileName = beginFileData.getFileName().replace("yyyy-MM-dd", nowDateString);
       newFileName = (newFileName.indexOf(".") != -1 ? newFileName.substring(0, newFileName.lastIndexOf(".")) : newFileName);
       }
       target = new File(newFileName +'.'+nowDateString+'.' + getIndex(1,maxBackupIndexLeng));
       this.closeFile(); 
       file = new File(fileName);
       LogLog.debug("Renaming file " + file + " to " + target);
      
       renameSucceeded = file.renameTo(target);
       //
       //   if file rename failed, reopen file with append = true
       //
       if (!renameSucceeded) {
           try {
             this.setFile(fileName, true, bufferedIO, bufferSize);
           }
           catch(IOException e) {
             LogLog.error("setFile("+fileName+", true) call failed.", e);
           }
       }
     }
     }
     //
     //   if all renames were successful, then
     //
     if (renameSucceeded) {
      
     try {
       // This will also close the file. This is OK since multiple
       // close operations are safe.
  
       this.setFile(fileName, false, bufferedIO, bufferSize);
       nextRollover = 0;
     }
     catch(IOException e) {
       LogLog.error("setFile("+fileName+", false) call failed.", e);
     }
     }
   }




   /**
    * 文件个数的长度补零，如果文件个数为10那么文件的个数长度就是2位，第一个文件就是01，02，03....
    * @param i
    * @param maxBackupIndexLeng
    * @return
    */
   private String getIndex(int i,int maxBackupIndexLeng){
    String index = String.valueOf(i);
    int len = index.length();
    for(int j = len; j<maxBackupIndexLeng;j++){
     index ="0"+index;
    }
    return index+".log";
   }
 



   /**
      This method differentiates RollingFileAppender from its super
      class.
      @since 0.9.0
   */
   protected
   void subAppend(LoggingEvent event) {
     super.subAppend(event);
     if(fileName != null && qw != null) {
      
       String nowDate = sdf.format(new Date());
    //检测日期是否已经变更了，如果变更了就要重创建日期目录
    if(!fileMaps.get(fileName).getDate().equals(nowDate)){
     rollOver();
     return;
    }
      
         long size = ((CountingQuietWriter) qw).getCount();
         if (size >= maxFileSize && size >= nextRollover) {
             rollOver();
         }
     }
    }
   
 

 
 @Override
 public synchronized void setFile(String fileName, boolean append,
   boolean bufferedIO, int bufferSize) throws IOException {
  
   String nowDate = sdf.format(new Date());
   //如果文件路径包含了“yyyy-MM-dd”就是每天一个日志目录的方式记录日志(第一次的时候)
   if(fileName.indexOf("yyyy-MM-dd") != -1){
    String beginFileName = fileName;
    fileName = fileName.replace("yyyy-MM-dd", nowDate);
    fileMaps.put(fileName, new BeginFileData(beginFileName,nowDate));
   }
   BeginFileData beginFileData = fileMaps.get(fileName);
   //检测日期是否已经变更了，如果变更了就要把原始的字符串给fileName变量，把变更后的日期做为开始日期
   if(!beginFileData.getDate().equals(nowDate)){
    //获取出第一次的文件名
    beginFileData.setDate(nowDate);
    fileName = beginFileData.getFileName().replace("yyyy-MM-dd", nowDate);
    fileMaps.put(fileName, beginFileData);
   }
   
   //D:/data/test/yyyy-MM-dd/test.log 替换yyyy-MM-dd为当前日期。
  
   super.setFile(fileName, append, this.bufferedIO, this.bufferSize);
 }
 



 class BeginFileData{
  
  public BeginFileData(String fileName, String date) {
   super();
   this.fileName = fileName;
   this.date = date;
  }
  private String fileName;
  private String date;
  public String getFileName() {
   return fileName;
  }
  public void setFileName(String fileName) {
   this.fileName = fileName;
  }
  public String getDate() {
   return date;
  }
  public void setDate(String date) {
   this.date = date;
  }
 }
}

log4j配置文件：
<appender class="com.mttang.log4j.MyRollingFileAppender">
<param value="D:/data/test/yyyy-MM-dd/test.log"/>
<param value="true"/>
<param value="50KB"/><!-每个文件50KB->
<param value="10"/><!-每天的日期目录下10个日志文件->

<layout class="org.apache.log4j.PatternLayout">
  <param value="%c %d{ISO8601}-- %p -- %m%n"/>
</layout>
<filter class="org.apache.log4j.varia.LevelRangeFilter">
  <param value="INFO" />
  <param value="INFO" />
  <param value="         http://wwww.baoshengdianzi.com          " />

</filter>
</appender>
金属膜电阻供应商 http://wwww.baoshengdianzi.com