利用线程池多线程解压文件提高解压效率

最新推荐文章于 2024-10-25 14:45:32 发布

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最新推荐文章于 2024-10-25 14:45:32 发布

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分类专栏：日积月累文章标签：多线程线程池 java

本文链接：https://blog.youkuaiyun.com/hiscoming/article/details/117925030

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该博客介绍了一种通过线程池实现大文件解压效率提升的方法。在Java中，通过创建固定大小的线程池，将ZipEntry元素分配给任务并执行，从而并行解压文件。每个任务负责读取ZipEntry对应的输入流，并将其写入到目标文件。实测证明，这种方法能有效加快解压过程。

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在解压大文件时，利用线程池多线程解压文件提高解压效率，参考网络资源，实测有效：

private void decompress(String srcPath, String destPath) throws IOException {

	long start = System.currentTimeMillis();
	this.zipFile = new ZipFile(srcPath);
	this.destPath = destPath;

	Enumeration<? extends ZipEntry> entries = zipFile.entries();

	ExecutorService threadPool = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
	// Log.i("ERIC", "// decompress()//==========entries.hasMoreElements()= " + entries.hasMoreElements());
	while (entries.hasMoreElements()) {
		ZipEntry zipEntry = entries.nextElement();

		if (zipEntry.isDirectory()) {
		continue;
		}

		threadPool.execute(new FileWritingTask(zipEntry));
	}
	Log.i("ERIC", "// decompress()//==========threadPool.shutdown()========== " );
	threadPool.shutdown();
	SystemProperties.set("persist.elmo.copyfiles", "false");
	try {
		threadPool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
	} catch (InterruptedException e) {
		e.printStackTrace();
	}
	zipFile.close();

	long end = System.currentTimeMillis();
	// Log.i("ERIC","解压完成，所用时间为：" + (end - start) + "ms");

}



private class FileWritingTask implements Runnable {

	private ZipEntry zipEntry;

	FileWritingTask(ZipEntry zipEntry) {
		this.zipEntry = zipEntry;
	}

	@Override
	public void run() {
		File file = new File(destPath + File.separator + zipEntry.getName());
		Log.i("ERIC", "// FileWritingTask file= " + file.getAbsolutePath());

		File parentFile = file.getParentFile();
		if (!parentFile.exists()) {
			parentFile.mkdirs();
		}
		try (
			InputStream inputStream = zipFile.getInputStream(this.zipEntry);
			OutputStream outputStream = new FileOutputStream(file);
		) {
			
			int read;
			byte[] bytes = new byte[inputStream.available()];
			while ((read = inputStream.read(bytes)) != -1) {
			outputStream.write(bytes, 0, read);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}