Java编写超时工具类实例讲解

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

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

 /**
  * 有超时限制的方法
  *
  * @param bizSupplier 业务函数
  * @param timeout   超时时间，ms
  * @return 返回值
  */
 public <R> Result<R> doWithTimeLimit(Supplier<R> bizSupplier, int timeout) {
   return doWithTimeLimit(bizSupplier, null, timeout);
 }

 /**
  * 有超时限制的方法
  *
  * @param bizSupplier  业务函数
  * @param defaultResult 默认值
  * @param timeout    超时时间，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执行超过%d毫秒，强制结束", timeout);
     log.error(errMsg, e);
     futureTask.cancel(true);
     result = defaultResult;
   }
   return of(result, errMsg);
 }

 /**
  * 随机耗时的测试方法
  */
 private String randomSpentTime() {
   Random random = new Random();
   int time = (random.nextInt(10) + 1) * 1000;
   log.info("预计randomSpentTime方法执行将耗时： " + 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);
         // 以守护线程方式启动
         thread.setDaemon(true);
         return thread;
       });
   TimeoutUtil timeoutUtil = new TimeoutUtil(executorService);
   for (int i = 1; i <= 10; i++) {
     log.info("\n=============第{}次超时测试=============", i);
     Thread.sleep(6000);
     long start = System.currentTimeMillis();
     String result = timeoutUtil.doWithTimeLimit(() -> timeoutUtil.randomSpentTime(), 5000).getOrElse("默认");
     log.info("doWithTimeLimit方法实际耗时{}毫秒，结果：{}", System.currentTimeMillis() - start, result);
   }
 }


}

/**
   * 校验对象中的属性。如果属性为null,抛异常。如果属性为字符串（空串或空格），抛异常。
   * @author mex
   * @date 2019年4月18日
   * @param e 对象
   * @param fieldNames 属性名称数组
   * @return void
   * @throws Exception
   */
  public static <E> void validateAttr(E e, String[] fieldNames) throws Exception {
    if (null == e) {
      throw new Exception("请求对象为空");
    }
    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);
      // 判断该属性为null的情况
      if (null == fieldValue) {
        throw new Exception("请求字段：" + fieldName + "不能为空");
      }
      // 如果该属性为字符串，判断其为空或空格的情况
      if ("java.lang.String".equals(typeName)) {
        if (StringUtils.isBlank((String)fieldValue)) {
          throw new Exception("请求字段：" + fieldName + "不能为空");
        }
      }
    }
  }