Java使用FutureTask实现预加载的示例详解

    static class ProductInfo {
        public ProductInfo(String name, String order_id) {
            this.name = name;
            this.order_id = order_id;
        }
        private String name;
        private String order_id;
        @Override
        public String toString() {
            return "ProductInfo{" +
                    "name='" + name + '\'' +
                    ", order_id='" + order_id + '\'' +
                    '}';
        }
    }

    static class Preloader {
        public void start() {
            thread.start();
        }
        private final FutureTask<ProductInfo> futureTask =
                new FutureTask<>(new Callable<ProductInfo>() {
                    @Override
                    public ProductInfo call() throws Exception {
                        return loadProductInfo();
                    }
                });
        public ProductInfo get() throws ExecutionException, 
        InterruptedException {
            return futureTask.get();
        }
        private final Thread thread = new Thread(futureTask);
        private ProductInfo loadProductInfo() {
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            return new ProductInfo("衣服", "9527");
        }
    }

    Preloader preloader = new Preloader();
        preloader.start();
        System.out.println("start get product info before"
         + System.currentTimeMillis() / 1000);
        ProductInfo productInfo = null;
        try {
            productInfo = preloader.get();
        } catch (ExecutionException | InterruptedException e) {
            throw new RuntimeException(e);
        }
        System.out.println("start get product info afte" 
        +System.currentTimeMillis() / 1000);
        System.out.println("productInfo: " + productInfo);