@@ -67,6 +67,10 @@ public class RollingFileAppenderExt extends RollingFileAppender {
     super.subAppend(event);
   }
 
+  public void setMaxBackupIndex(int maxBackups) {
+    super.setMaxBackupIndex(maxBackups);
+  }
+
   protected void createCurrentFile() throws IOException {
     if (!currentFile.exists()) {
       File parent = currentFile.getParentFile();
/*
 * Copyright 2017 Huawei Technologies Co., Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.servicecomb.foundation.common.utils;

import java.io.File;
import java.io.IOException;

import org.apache.log4j.RollingFileAppender;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

/**
 * 扩展增加2个功能：1. 设置文件权限；2. 文件删除后重建。
 */
public class RollingFileAppenderExt extends RollingFileAppender {
  private File currentFile;

  private boolean append;

  private String logPermission;

  public String getLogPermission() {
    return logPermission;
  }

  public void setLogPermission(String logPermission) {
    this.logPermission = logPermission;
  }

  @Override
  public void setFile(String file) {
    super.setFile(file);
  }

  @Override
  public void setFile(String fileName, boolean append, boolean bufferedIO, int bufferSize) throws IOException {
    this.append = append;
    currentFile = new File(fileName);
    createCurrentFile();
    super.setFile(fileName, append, bufferedIO, bufferSize);
  }

  @Override
  protected void subAppend(LoggingEvent event) {
    // create a new file when file deleted
    if (!currentFile.exists()) {
      try {
        setFile(fileName, append, bufferedIO, bufferSize);
      } catch (IOException e) {
        LogLog.error("", e);
      }
    }
    super.subAppend(event);
  }

  protected void createCurrentFile() throws IOException {
    if (!currentFile.exists()) {
      File parent = currentFile.getParentFile();
      if (parent != null && !parent.exists()) {
        parent.mkdirs();
      }
      currentFile.createNewFile();
    }
    FilePerm.setFilePerm(currentFile, logPermission);
  }
}

why need to add this code? base class already public it.