java8 function 活用

問題：有多個方法含有以下類似的重複代碼，以後可能會需要更多傳回不同類型的方法。通過什麼方式可以避免代碼重複，任何方式都可以。某些設計模式可行嗎？

public static Date readDate(String dir, String fileName) {
	Path path = Paths.get(dir, fileName);
	try (BufferedReader br = Files.newBufferedReader(path)) {
	    String result = br.readLine();
	    return DateUtils.parseDate(result, "yyyy-MM-dd");
	} catch (IOException e) {
	    log.error("read fail file: " + path);
	} catch (ParseException e) {
	    e.printStackTrace();
	}
	return null;
    }

    public static Integer readInteger(String dir, String fileName) {
	Path path = Paths.get(dir, fileName);
	try (BufferedReader br = Files.newBufferedReader(path)) {
	    String result = br.readLine();
	    return Integer.valueOf(result);
	} catch (IOException e) {
	    log.error("read fail file: " + path);
	}
	return null;
    }
           

Analysis process: Return method is different, the one is return DateUtils.paseDate(result,"yyyy-MM-dd"), the anther one is return Integer.valueOf(result).

So someOne want to use Template method， In here I will use Java8 function to handle it.

public static <T> T read(String dir, String fileName, Function<String, T> fun) {
	Path path = Paths.get(dir, fileName);
	try (BufferedReader br = Files.newBufferedReader(path)) {
	    String result = br.readLine();
	    return fun.apply(result);
	} catch (IOException e) {
	    log.error("read fail file: " + path);
	}
	return null;
    }
           

The following code is revoke method.

@Test
    private void test() {
	read("/d", "test.txt", Integer::valueOf);
	read("/d", "test.txt", date -> {
	    try {
		return DateUtils.parseDate(date, "yyyy-MM-dd");
	    } catch (ParseException e) {
		e.printStackTrace();
	    }
	    return null;
	});
    }