Combo Handler 简单实现

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public class ComboTest {
	public static void main(String[] args) throws IOException, NoSuchAlgorithmException {
		Runnable myRunnable = new Runnable() {
			@Override
			public void run() {
				try {
					test();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		};
		// 模拟请求
		for (int i = 0; i < 5; i++) {
			Thread thread = new Thread(myRunnable);
			thread.start();
		}
	}

	// 请求进入
	public static void test() throws Exception {
		String[] files = { "1.js", "2.js" };
		String outName = "";
		for (String temp : files) {
			outName += temp;
		}
		
		// 同样的请求进行唯一标识
		outName = string2MD5(outName);

		// 后缀添加版本号便于及时更新(v1应该在服务器启动时从配置中读取)
		outName = outName + "." + "v1";

		// 文件不存在进入合并方法制造合并文件，注意大量并发情况下会有多个线程进入
		File file = new File("F:", outName);
		if (!file.exists()) {
			createComboFile("F:", files, "F:", outName);
		}
		System.out.println(Thread.currentThread().getName() + "读取到：" + file.getName() + " size:" + file.length());
	}
	
	
	//合并文件，synchronized，让第一个进来的顺利完成
	public static synchronized void createComboFile(String inBasePath, String[] files, String outBasePath, String outName) throws IOException, InterruptedException {
		File f1 = new File(outBasePath, outName);
		File f2 = new File(outBasePath, outName + ".temp");
		if (f1.exists() || f2.exists()) {
			System.out.println(Thread.currentThread().getName() + "跳过创建");
			return;
		} else {
			f2.createNewFile();
			System.out.println(Thread.currentThread().getName() + "创建文件");
		}
		
		//文件合并
		FileOutputStream out = new FileOutputStream(f2);
		int len = 0;
		byte[] buf = new byte[2048];
		for (int i = 0; i < files.length; i++) {
			File p = new File(inBasePath, files[i]);
			FileInputStream fin = new FileInputStream(p);
			while ((len = fin.read(buf)) != -1) {
				out.write(buf, 0, len);
			}
			// 另起一行
			out.write("\n".getBytes());
			fin.close();
		}
		out.flush();
		out.close();
        //重命名
		f2.renameTo(f1);
	}
}