java项目技巧一

引用

1.最近做个项目，需求：每生成一个订单，给相应的用户发一条短信。短信模板存放在txt文件。模板以${mobile} 之类的作为占位符。文件的读取部分，抄红薯的开源代码

public class MyUtil {
	private static final Logger log = Logger.getLogger(MyUtil.class);
	private static final String TEMPLATE = "/msgTemplate.txt";
	private static long lastCheck = -1L;
	private static long lastModified = -1L;
	private static final long CHECK_INTERVAL = 180000; // 3分钟检查一次
	private static StringBuffer context = new StringBuffer();

	// 模板文件读取
	public static String getTemplate() throws IOException {
		long ct = System.currentTimeMillis();
		if ((ct - lastCheck) > CHECK_INTERVAL) {
			File tmpFile = new File(TEMPLATE);
			if (tmpFile.lastModified() > lastModified) {
				synchronized (MyUtil.class) {
					String tmp = null;
					BufferedReader breader = null;
					try {
						breader = new BufferedReader(new InputStreamReader(
								new FileInputStream(tmpFile)));
						while ((tmp = breader.readLine()) != null) {
							context.append(tmp);
						}
					} finally {
						breader.close();
					}
					lastModified = tmpFile.lastModified();
				}
			}
			lastCheck = ct;
		}
		return context.toString();
	}

	// 模板内容替换
	public String getMsgByTemplate(Object obj) throws IOException,
			SecurityException, NoSuchFieldException, IllegalArgumentException,
			IllegalAccessException {
		Class<?> clazz = obj.getClass();
		String context = MyUtil.getTemplate(); // 得到模板内容
		Set<String> set = new HashSet<String>();

		int i = 0;
		while (i < context.length()) {
			int index = context.indexOf("${", i);
			int end = context.indexOf("}", index);
			if (index == -1)
				break; // 找不到以${开头 中止循环
			set.add(context.substring(index + 2, end).trim()); // 取得${mobile} 的
			// 'mobile' 字符串
		}

		Map<String, String> map = new HashMap<String, String>();
		Iterator<String> iterator = set.iterator();
		while (iterator.hasNext()) {
			String tmp = iterator.next();
			Field field = clazz.getDeclaredField(tmp);
			field.setAccessible(true);
			String value = field.get(obj).toString();
			map.put(tmp, value); // 如map.put("mobile","13560023645");
		}

		for (Map.Entry<String, String> entry : map.entrySet()) {
			// 替换模板中的类似${mobile}的占位符 为真正的字符.。
			context = context.replaceAll("\\$\\{" + entry.getKey() + "\\}",
					entry.getValue());
		}

		return context;
	}