content: /* ====================================================================
     Licensed to the Apache Software Foundation (ASF) under one or more
     contributor license agreements.  See the NOTICE file distributed with
     this work for additional information regarding copyright ownership.
     The ASF licenses this file to You 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 com.alibaba.excel.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.nio.file.attribute.FileAttribute;
  import java.util.concurrent.locks.Lock;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.apache.poi.util.DefaultTempFileCreationStrategy;
  import org.apache.poi.util.TempFileCreationStrategy;
  
  import static org.apache.poi.util.TempFile.JAVA_IO_TMPDIR;
  
  /**
   * In the scenario where `poifiles` are cleaned up, the {@link DefaultTempFileCreationStrategy} will throw a
   * java.nio.file.NoSuchFileException. Therefore, it is necessary to verify the existence of the temporary file every
   * time it is created.
   *
   * @author Jiaju Zhuang
   */
  public class EasyExcelTempFileCreationStrategy implements TempFileCreationStrategy {
      /**
       * Name of POI files directory in temporary directory.
       */
      public static final String POIFILES = "poifiles";
  
      /**
       * To use files.deleteOnExit after clean JVM exit, set the <code>-Dpoi.delete.tmp.files.on.exit</code> JVM property
       */
      public static final String DELETE_FILES_ON_EXIT = "poi.delete.tmp.files.on.exit";
  
      /**
       * The directory where the temporary files will be created (<code>null</code> to use the default directory).
       */
      private volatile File dir;
  
      /**
       * The lock to make dir initialized only once.
       */
      private final Lock dirLock = new ReentrantLock();
  
      /**
       * Creates the strategy so that it creates the temporary files in the default directory.
       *
       * @see File#createTempFile(String, String)
       */
      public EasyExcelTempFileCreationStrategy() {
          this(null);
      }
  
      /**
       * Creates the strategy allowing to set the
       *
       * @param dir The directory where the temporary files will be created (<code>null</code> to use the default
       *            directory).
       * @see Files#createTempFile(Path, String, String, FileAttribute[])
       */
      public EasyExcelTempFileCreationStrategy(File dir) {
          this.dir = dir;
      }
  
      private void createPOIFilesDirectory() throws IOException {
          // Create our temp dir only once by double-checked locking
          // The directory is not deleted, even if it was created by this TempFileCreationStrategy
          if (dir == null || !dir.exists()) {
              dirLock.lock();
              try {
                  if (dir == null || !dir.exists()) {
                      String tmpDir = System.getProperty(JAVA_IO_TMPDIR);
                      if (tmpDir == null) {
                          throw new IOException("System's temporary directory not defined - set the -D" + JAVA_IO_TMPDIR
                              + " jvm property!");
                      }
                      Path dirPath = Paths.get(tmpDir, POIFILES);
                      dir = Files.createDirectories(dirPath).toFile();
                  }
              } finally {
                  dirLock.unlock();
              }
              return;
          }
      }
  
      @Override
      public File createTempFile(String prefix, String suffix) throws IOException {
          // Identify and create our temp dir, if needed
          createPOIFilesDirectory();
  
          // Generate a unique new filename
          File newFile = Files.createTempFile(dir.toPath(), prefix, suffix).toFile();
  
          // Set the delete on exit flag, but only when explicitly disabled
          if (System.getProperty(DELETE_FILES_ON_EXIT) != null) {
              newFile.deleteOnExit();
          }
  
          // All done
          return newFile;
      }
  
      /* (non-JavaDoc) Created directory path is <JAVA_IO_TMPDIR>/poifiles/prefix0123456789 */
      @Override
      public File createTempDirectory(String prefix) throws IOException {
          // Identify and create our temp dir, if needed
          createPOIFilesDirectory();
  
          // Generate a unique new filename
          File newDirectory = Files.createTempDirectory(dir.toPath(), prefix).toFile();
  
          //this method appears to be only used in tests, so it is probably ok to use deleteOnExit
          newDirectory.deleteOnExit();
  
          // All done
          return newDirectory;
      }
  }
  