Servlet中的異步進程

Question

我想等待每個請求10秒的請求，但請求不必等待對方。所以第二個請求不必等待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 { 

     } 
    } 

我的異步過程類：

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

這將是更優的調度請求的完成而不會阻塞的線程。下面是修改後的代碼（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(); 
    } 
} 

請注意，根據您的運行時環境（即容器），你可能不會被允許創建自己的遺囑執行人，並可能需要使用一個由EE容器提供。