Java編寫超時工具類實例講解

/**
 * TimeoutUtil <br>
 *
 * @author lys
 * @date 2021/2/25
 */

@Slf4j
@Component
@NoArgsConstructor
public class TimeoutUtil {
 private ExecutorService executorService;
 public TimeoutUtil(ExecutorService executorService) {
   this.executorService = executorService;
 }

 /**
  * 有超時限制的方法
  *
  * @param bizSupplier 業務函數
  * @param timeout   超時時間，ms
  * @return 返回值
  */
 public <R> Result<R> doWithTimeLimit(Supplier<R> bizSupplier, int timeout) {
   return doWithTimeLimit(bizSupplier, null, timeout);
 }

 /**
  * 有超時限制的方法
  *
  * @param bizSupplier  業務函數
  * @param defaultResult 默認值
  * @param timeout    超時時間，ms
  * @return 返回值
  */
 public <R> Result<R> doWithTimeLimit(Supplier<R> bizSupplier, R defaultResult, int timeout) {

   R result;
   String errMsg = "Null value";
   FutureTask<R> futureTask = new FutureTask<>(bizSupplier::get);
   executorService.execute(futureTask);
   try {
     result = futureTask.get(timeout, TimeUnit.MILLISECONDS);
   } catch (InterruptedException | ExecutionException | TimeoutException e) {
     errMsg = String.format("doWithTimeLimit執行超過%d毫秒，強制結束", timeout);
     log.error(errMsg, e);
     futureTask.cancel(true);
     result = defaultResult;
   }
   return of(result, errMsg);
 }

 /**
  * 隨機耗時的測試方法
  */
 private String randomSpentTime() {
   Random random = new Random();
   int time = (random.nextInt(10) + 1) * 1000;
   log.info("預計randomSpentTime方法執行將耗時： " + time + "毫秒");
   try {
     Thread.sleep(time);
   } catch (Exception e) {
   }
   return "randomSpentTime --> " + time;
 }

 public static void main(String[] args) throws Exception {
   ExecutorService executorService = new ThreadPoolExecutor(1, 1,
       0L, TimeUnit.MILLISECONDS,
       new LinkedBlockingQueue<Runnable>(),
       runnable -> {
         Thread thread = new Thread(runnable);
         // 以守護線程方式啟動
         thread.setDaemon(true);
         return thread;
       });
   TimeoutUtil timeoutUtil = new TimeoutUtil(executorService);
   for (int i = 1; i <= 10; i++) {
     log.info("\n=============第{}次超時測試=============", i);
     Thread.sleep(6000);
     long start = System.currentTimeMillis();
     String result = timeoutUtil.doWithTimeLimit(() -> timeoutUtil.randomSpentTime(), 5000).getOrElse("默認");
     log.info("doWithTimeLimit方法實際耗時{}毫秒，結果：{}", System.currentTimeMillis() - start, result);
   }
 }


}

/**
   * 校驗對象中的屬性。如果屬性為null,拋異常。如果屬性為字符串（空串或空格），拋異常。
   * @author mex
   * @date 2019年4月18日
   * @param e 對象
   * @param fieldNames 屬性名稱數組
   * @return void
   * @throws Exception
   */
  public static <E> void validateAttr(E e, String[] fieldNames) throws Exception {
    if (null == e) {
      throw new Exception("請求對象為空");
    }
    if (null == fieldNames) {
      return;
    }
    for (int i = 0; i < fieldNames.length; i++) {
      String fieldName = fieldNames[i];
      Field field = e.getClass().getDeclaredField(fieldName);
      String typeName = field.getGenericType().getTypeName();
      field.setAccessible(Boolean.TRUE);
      Object fieldValue = field.get(e);
      // 判斷該屬性為null的情況
      if (null == fieldValue) {
        throw new Exception("請求字段：" + fieldName + "不能為空");
      }
      // 如果該屬性為字符串，判斷其為空或空格的情況
      if ("java.lang.String".equals(typeName)) {
        if (StringUtils.isBlank((String)fieldValue)) {
          throw new Exception("請求字段：" + fieldName + "不能為空");
        }
      }
    }
  }