正则表达式与EndWith的性能比较-优快云博客

本文通过两个方法比较了正则表达式匹配与字符串EndWith方法在处理大量文件名匹配任务时的性能差异。实验结果显示，在给定的100万次迭代条件下，使用EndWith方法比正则表达式快约219毫秒。

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性能比较：

	public static void main(String[] args) throws Exception {
		System.out.println("======Begin Test======");
		test1();
		test2();
		System.out.println("======End Test======");
	}

	public static void test1() {
		Pattern pattern = Pattern.compile("\\.(jpg|png|gif)$", Pattern.CASE_INSENSITIVE);
		String fileName = "agifpngjpgb.GIF";

		long begin = System.currentTimeMillis();
		for (int i = 1000000; i > 0; i--) {
			Matcher matcher = pattern.matcher(fileName);
			matcher.find();
		}
		long end = System.currentTimeMillis();
		System.out.println("regexp: " + (end - begin));
	}

	public static void test2() {
		String[] suffixs = { "jpg", "png", "gif" };
		String fileName = "agifpngjpgb.GIF";
		String temp = null;

		long begin = System.currentTimeMillis();
		for (int i = 1000000; i > 0; i--) {
			temp = fileName.toLowerCase();
			check1(suffixs, temp);
		}
		long end = System.currentTimeMillis();
		System.out.println("endwith: " + (end - begin));
	}

	private static boolean check1(String[] suffixs, String fileName) {
		for (String suffix : suffixs) {
			if (fileName.endsWith(suffix)) {
				return true;
			}
		}
		return false;
	}

运行结果：

======Begin Test======
regexp: 578
endwith: 359
======End Test======