java8异步处理学习
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https://blog.51cto.com/u_16297326/13571760
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总结:
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CompletableFuture 是 Java 中实现异步编程的强大工具，它提供了丰富的 API 来创建、组合和处理异步任务，
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能够帮助开发者构建高性能、高响应性的应用程序。通过本文的详细介绍和代码示例，
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读者应该对 CompletableFuture 的基本使用、链式调用、组合多个任务、异常处理以及实际应用等方面有了深入的了解。
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在实际开发中，灵活运用 CompletableFuture 的特性，结合性能优化和最佳实践，能够有效提升应用程序的性能和用户体验。
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随着 Java 技术的不断发展和应用场景的日益复杂，掌握 CompletableFuture 等异步编程技术对于 Java 开发者来说显得尤为重要。
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七、实际应用案例：构建复杂的异步工作流
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为了更好地理解 CompletableFuture 的实际应用，我们来看一个构建复杂异步工作流的案例。
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假设我们需要开发一个电商订单处理系统，其中包含多个异步任务，如验证用户信息、检查库存、计算运费、处理支付等。
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这些任务之间存在一定的依赖关系，需要合理地组合和处理。
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// 验证用户信息
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CompletableFuture<User> validateUserAsync(String userId) {
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return CompletableFuture.supplyAsync(() -> {
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System.out.println("Validating user...");
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// 模拟网络延迟
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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// 返回用户对象
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return new User(userId);
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});
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}
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// 检查库存
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CompletableFuture<Boolean> checkInventoryAsync(Product product, int quantity) {
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return CompletableFuture.supplyAsync(() -> {
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System.out.println("Checking inventory for product: " + product.getId());
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// 模拟网络延迟
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try {
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Thread.sleep(1500);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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// 返回是否有足够库存
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return product.getStock() >= quantity;
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});
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}
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// 计算运费
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CompletableFuture<Double> calculateShippingCostAsync(User user, double totalWeight) {
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return CompletableFuture.supplyAsync(() -> {
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System.out.println("Calculating shipping cost...");
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// 模拟网络延迟
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try {
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Thread.sleep(1200);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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// 根据用户地址和总重量计算运费
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return totalWeight * 0.5;
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});
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}
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// 处理支付
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CompletableFuture<Boolean> processPaymentAsync(User user, double amount) {
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return CompletableFuture.supplyAsync(() -> {
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System.out.println("Processing payment...");
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// 模拟网络延迟
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try {
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Thread.sleep(1800);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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// 返回支付是否成功
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return true;
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});
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}
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// 构建订单处理工作流
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public void processOrder(String userId, Product product, int quantity) {
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// 验证用户信息
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CompletableFuture<User> userFuture = validateUserAsync(userId);
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// 检查库存
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CompletableFuture<Boolean> inventoryFuture = userFuture
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.thenCompose(user -> checkInventoryAsync(product, quantity));
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// 计算运费
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CompletableFuture<Double> shippingCostFuture = inventoryFuture
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.thenCompose(hasInventory -> {
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if (hasInventory) {
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return calculateShippingCostAsync(userFuture.join(), product.getWeight() * quantity);
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} else {
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return CompletableFuture.completedFuture(0.0);
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}
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});
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// 处理支付
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CompletableFuture<Boolean> paymentFuture = shippingCostFuture
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.thenCompose(shippingCost -> {
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double totalAmount = product.getPrice() * quantity + shippingCost;
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return processPaymentAsync(userFuture.join(), totalAmount);
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});
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// 最终处理
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paymentFuture
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.thenAccept(paymentSuccess -> {
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if (paymentSuccess) {
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System.out.println("Order processed successfully.");
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} else {
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System.out.println("Payment failed, order not processed.");
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}
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})
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.exceptionally(ex -> {
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System.out.println("Error occurred during order processing: " + ex.getMessage());
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return null;
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})
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.join();
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}
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