Servlet中的异步进程

Question

我想等待每个请求10秒的请求，但请求不必等待对方。所以第二个请求不必等待20秒。

我的servlet：

@WebServlet(value = "/account", asyncSupported = true) 
    public class AccountServlet extends javax.servlet.http.HttpServlet { 

     public AccountServlet() { 

     } 

     @Override 
     protected void doGet(HttpServletRequest request, HttpServletResponse response) { 
      AsyncContext ac = request.startAsync(); 

      ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(10); 
      executor.execute(new MyAsyncService(ac)); 
     } 

     @Override 
     public void init(ServletConfig config) throws ServletException { 

     } 
    } 

我的异步过程类：

class MyAsyncService implements Runnable { 

     AsyncContext ac; 

     public MyAsyncService(AsyncContext ac) { 
      this.ac = ac; 
     } 

     @Override 
     public void run() { 
      try { 
       System.out.println("started"); 
       Thread.sleep(10000); 
       System.out.println("completed"); 
       ac.complete(); 
      } catch (InterruptedException ex) { 
       Logger.getLogger(MyAsyncService.class.getName()).log(Level.SEVERE, null, ex); 
      } 
     } 
    } 

Answer 1

这将是更优的调度请求的完成而不会阻塞的线程。下面是修改后的代码（使用Java 8 lambda）。

@WebServlet(value = "/account", asyncSupported = true) 
public class AccountServlet extends javax.servlet.http.HttpServlet { 
    private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(); 

    @Override 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) { 
     AsyncContext ac = request.startAsync(); 
     executor.schedule(ac::complete, 10, TimeUnit.SECONDS); 
    } 

    @Override 
    public void destroy() { 
     executor.shutdown(); 
    } 
} 

请注意，根据您的运行时环境（即容器），你可能不会被允许创建自己的遗嘱执行人，并可能需要使用一个由EE容器提供。