java 方法要求固定时间返回值

package net.highersoft.service;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class TestTime {
	private static Logger log=LoggerFactory.getLogger(TestTime.class);

	public static void main(String[] args) {
		testMethod();

	}
	public static void testMethod() {
        CompletableFuture<Object> future = CompletableFuture.supplyAsync(() -> {
            try {
            	int randTime=(int)(Math.random()*5000);
            	 System.out.println("sleep:"+randTime);
                Thread.sleep(randTime);
               
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new RuntimeException("Interrupted", e);
            }
            return "abc";
           
        });
        try {
            Object rst=future.get(2000, TimeUnit.MILLISECONDS);
            System.out.println("return:"+rst);
        } catch (TimeoutException e) {
            // Operation timed out. Cancel it and log.
            future.cancel(true);
            log.error("Timed out", e);
        } catch (InterruptedException e) {
            // Current thread interrupted while waiting. Cancel operation and log.
            future.cancel(true);
            log.error("Interrupted", e);
            // Reassert interrupt flag, since exception is not propagated.
            Thread.currentThread().interrupt();
        } catch (ExecutionException e) {
            log.error("Operation failed", e.getCause());
            // No need to cancel in this case, since the operation has completed.
        }
    }

}