mirror of https://github.com/alibaba/easyexcel
Jiaju Zhuang
5 months ago
5 changed files with 152 additions and 11 deletions
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/* ==================================================================== |
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Licensed to the Apache Software Foundation (ASF) under one or more |
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contributor license agreements. See the NOTICE file distributed with |
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this work for additional information regarding copyright ownership. |
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The ASF licenses this file to You under the Apache License, Version 2.0 |
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(the "License"); you may not use this file except in compliance with |
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the License. You may obtain a copy of the License at |
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software |
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distributed under the License is distributed on an "AS IS" BASIS, |
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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See the License for the specific language governing permissions and |
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limitations under the License. |
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==================================================================== */ |
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package com.alibaba.excel.util; |
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import java.io.File; |
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import java.io.IOException; |
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import java.nio.file.Files; |
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import java.nio.file.Path; |
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import java.nio.file.Paths; |
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import java.nio.file.attribute.FileAttribute; |
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import java.util.concurrent.locks.Lock; |
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import java.util.concurrent.locks.ReentrantLock; |
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import org.apache.poi.util.DefaultTempFileCreationStrategy; |
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import org.apache.poi.util.TempFileCreationStrategy; |
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import static org.apache.poi.util.TempFile.JAVA_IO_TMPDIR; |
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/** |
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* In the scenario where `poifiles` are cleaned up, the {@link DefaultTempFileCreationStrategy} will throw a |
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* java.nio.file.NoSuchFileException. Therefore, it is necessary to verify the existence of the temporary file every |
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* time it is created. |
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* |
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* @author Jiaju Zhuang |
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*/ |
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public class EasyExcelTempFileCreationStrategy implements TempFileCreationStrategy { |
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/** |
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* Name of POI files directory in temporary directory. |
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*/ |
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public static final String POIFILES = "poifiles"; |
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/** |
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* To use files.deleteOnExit after clean JVM exit, set the <code>-Dpoi.delete.tmp.files.on.exit</code> JVM property |
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*/ |
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public static final String DELETE_FILES_ON_EXIT = "poi.delete.tmp.files.on.exit"; |
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/** |
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* The directory where the temporary files will be created (<code>null</code> to use the default directory). |
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*/ |
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private volatile File dir; |
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/** |
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* The lock to make dir initialized only once. |
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*/ |
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private final Lock dirLock = new ReentrantLock(); |
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/** |
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* Creates the strategy so that it creates the temporary files in the default directory. |
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* |
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* @see File#createTempFile(String, String) |
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*/ |
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public EasyExcelTempFileCreationStrategy() { |
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this(null); |
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} |
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/** |
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* Creates the strategy allowing to set the |
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* |
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* @param dir The directory where the temporary files will be created (<code>null</code> to use the default |
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* directory). |
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* @see Files#createTempFile(Path, String, String, FileAttribute[]) |
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*/ |
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public EasyExcelTempFileCreationStrategy(File dir) { |
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this.dir = dir; |
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} |
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private void createPOIFilesDirectory() throws IOException { |
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// Create our temp dir only once by double-checked locking
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// The directory is not deleted, even if it was created by this TempFileCreationStrategy
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if (dir == null || !dir.exists()) { |
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dirLock.lock(); |
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try { |
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if (dir == null || !dir.exists()) { |
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String tmpDir = System.getProperty(JAVA_IO_TMPDIR); |
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if (tmpDir == null) { |
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throw new IOException("System's temporary directory not defined - set the -D" + JAVA_IO_TMPDIR |
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+ " jvm property!"); |
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} |
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Path dirPath = Paths.get(tmpDir, POIFILES); |
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dir = Files.createDirectories(dirPath).toFile(); |
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} |
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} finally { |
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dirLock.unlock(); |
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} |
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return; |
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} |
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} |
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@Override |
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public File createTempFile(String prefix, String suffix) throws IOException { |
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// Identify and create our temp dir, if needed
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createPOIFilesDirectory(); |
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// Generate a unique new filename
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File newFile = Files.createTempFile(dir.toPath(), prefix, suffix).toFile(); |
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// Set the delete on exit flag, but only when explicitly disabled
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if (System.getProperty(DELETE_FILES_ON_EXIT) != null) { |
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newFile.deleteOnExit(); |
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} |
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// All done
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return newFile; |
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} |
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/* (non-JavaDoc) Created directory path is <JAVA_IO_TMPDIR>/poifiles/prefix0123456789 */ |
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@Override |
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public File createTempDirectory(String prefix) throws IOException { |
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// Identify and create our temp dir, if needed
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createPOIFilesDirectory(); |
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// Generate a unique new filename
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File newDirectory = Files.createTempDirectory(dir.toPath(), prefix).toFile(); |
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//this method appears to be only used in tests, so it is probably ok to use deleteOnExit
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newDirectory.deleteOnExit(); |
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// All done
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return newDirectory; |
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} |
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} |
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