59、servlet3.0-异步请求

59、servlet3.0-异步请求

59.1 开启servlet异步请求步骤

1. 支持异步处理 asyncSupported=true
2. 开启异步模式 req.startAsync();
3. 业务逻辑进行异步处理;开始异步处理 asyncContext.start()
4. 获取响应 asyncContext.getResponse()

59.2 新建异步servlet处理类

@WebServlet(value = "/async", asyncSupported = true)
public class HelloAsyncServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        AsyncContext asyncContext = req.startAsync();
        System.out.println("主线程开始：" + Thread.currentThread() + "start..." + System.currentTimeMillis());
        asyncContext.start(() -> {
            try {
                System.out.println("子线程开始：" + Thread.currentThread() + "start..." + System.currentTimeMillis());
                sayHello();
                asyncContext.complete();
                ServletResponse response = asyncContext.getResponse();
                response.getWriter().write("异步执行完成");
                System.out.println("子线程结束：" + Thread.currentThread() + "end..." + System.currentTimeMillis());
            } catch (InterruptedException | IOException e) {
                e.printStackTrace();
            }
        });
        System.out.println("主线程结束：" + Thread.currentThread() + "end..." + System.currentTimeMillis());

    }

    public void sayHello() throws InterruptedException {
        System.out.println("主线程运行：" + Thread.currentThread() + "processing..." + System.currentTimeMillis());
        Thread.sleep(3000);
    }
}

59.3 测试用例