异步化，高并发大杀器

@WebServlet(name = "WorkServlet",urlPatterns = "/work",asyncSupported =true)
public class WorkServlet extends HttpServlet{
    private static final long serialVersionUID = 1L;
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置ContentType,关闭缓存
        resp.setContentType("text/plain;charset=UTF-8");
        resp.setHeader("Cache-Control","private");
        resp.setHeader("Pragma","no-cache");
        final PrintWriter writer= resp.getWriter();
        writer.println("老师检查作业了");
        writer.flush();
        List zuoyes=new ArrayList();
        for (int i = 0; i < 10; i++) {
            zuoyes.add("zuoye"+i);;
        }
        //开启异步请求
        final AsyncContext ac=req.startAsync();
        doZuoye(ac, zuoyes);
        writer.println("老师布置作业");
        writer.flush();
    }
    private void doZuoye(final AsyncContext ac, final List zuoyes) {
        ac.setTimeout(1*60*60*1000L);
        ac.start(new Runnable() {
            @Override
            public void run() {
                //通过response获得字符输出流
                try {
                    PrintWriter writer=ac.getResponse().getWriter();
                    for (String zuoye:zuoyes) {
                        writer.println("\""+zuoye+"\"请求处理中");
                        Thread.sleep(1*1000L);
                        writer.flush();
                    }
                    ac.complete();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

1.     <dependency>
2.          <groupId>javax.servlet</groupId>
3.          <artifactId>javax.servlet-api</artifactId>
4.          <version>3.1.0</version>
5.          <scope>provided</scope>
6.     </dependency>
7.     <dependency>
8.          <groupId>org.springframework</groupId>
9.          <artifactId>spring-webmvc</artifactId>
10.          <version>4.2.3.RELEASE</version>
11.     </dependency>

1.    <?xml version="1.0" encoding="UTF-8"?>
2.    <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
5.        http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
6.        <filter>
7.            <filter-name>testFilter</filter-name>
8.            <filter-class>com.TestFilter</filter-class>
9.            <async-supported>true</async-supported>
10.        </filter>
11.    
12.        <servlet>
13.            <servlet-name>mvc-dispatcher</servlet-name>
14.            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
15.            .........
16.            <async-supported>true</async-supported>
17.        </servlet>

1.    @RequestMapping(value="/asynctask", method = RequestMethod.GET)
2.        public DeferredResult<String> asyncTask() throws IOReactorException {
3.            IOReactorConfig ioReactorConfig = IOReactorConfig.custom().setIoThreadCount(1).build();
4.            ConnectingIOReactor ioReactor = new DefaultConnectingIOReactor(ioReactorConfig);
5.            PoolingNHttpClientConnectionManager conManager = new PoolingNHttpClientConnectionManager(ioReactor);
6.            conManager.setMaxTotal(100);
7.            conManager.setDefaultMaxPerRoute(100);
8.            CloseableHttpAsyncClient httpclient = HttpAsyncClients.custom().setConnectionManager(conManager).build();
9.            // Start the client
10.            httpclient.start();
11.            //设置超时时间200ms
12.            final DeferredResult<String> deferredResult = new DeferredResult<String>(200L);
13.            deferredResult.onTimeout(new Runnable() {
14.                @Override
15.                public void run() {
16.                    System.out.println("异步调用执行超时！thread id is : " + Thread.currentThread().getId());
17.                    deferredResult.setResult("超时了");
18.                }
19.            });
20.            System.out.println("/asynctask 调用！thread id is : " + Thread.currentThread().getId());
21.            final HttpGet request2 = new HttpGet("http://www.apache.org/");
22.            httpclient.execute(request2, new FutureCallback<HttpResponse>() {
23.    
24.                public void completed(final HttpResponse response2) {
25.                    System.out.println(request2.getRequestLine() + "->" + response2.getStatusLine());
26.                    deferredResult.setResult(request2.getRequestLine() + "->" + response2.getStatusLine());
27.                }
28.    
29.                public void failed(final Exception ex) {
30.                    System.out.println(request2.getRequestLine() + "->" + ex);
31.                }
32.    
33.                public void cancelled() {
34.                    System.out.println(request2.getRequestLine() + " cancelled");
35.                }
36.    
37.            });
38.            return deferredResult;
39.        }

1.    Object asyncManagerAttr = servletRequest.getAttribute(WEB_ASYNC_MANAGER_ATTRIBUTE);
2.    return asyncManagerAttr instanceof WebAsyncManager ;

1.    public class HTTPAsyncClientDemo {
2.        public static void main(String[] args) throws ExecutionException, InterruptedException, IOReactorException {
3.          //具体参数含义下文会讲
4.           //apache提供了ioReactor的参数配置，这里我们配置IO 线程为1
5.            IOReactorConfig ioReactorConfig = IOReactorConfig.custom().setIoThreadCount(1).build();
6.          //根据这个配置创建一个ioReactor
7.            ConnectingIOReactor ioReactor = new DefaultConnectingIOReactor(ioReactorConfig);
8.          //asyncHttpClient使用PoolingNHttpClientConnectionManager管理我们客户端连接
9.            PoolingNHttpClientConnectionManager conManager = new PoolingNHttpClientConnectionManager(ioReactor);
10.          //设置总共的连接的最大数量
11.            conManager.setMaxTotal(100);
12.          //设置每个路由的连接的最大数量
13.            conManager.setDefaultMaxPerRoute(100);
14.          //创建一个Client
15.            CloseableHttpAsyncClient httpclient = HttpAsyncClients.custom().setConnectionManager(conManager).build();
16.            // Start the client
17.            httpclient.start();
18.    
19.            // Execute request
20.            final HttpGet request1 = new HttpGet("http://www.apache.org/");
21.            Future<HttpResponse> future = httpclient.execute(request1, null);
22.            // and wait until a response is received
23.            HttpResponse response1 = future.get();
24.            System.out.println(request1.getRequestLine() + "->" + response1.getStatusLine());
25.    
26.            // One most likely would want to use a callback for operation result
27.            final HttpGet request2 = new HttpGet("http://www.apache.org/");
28.            httpclient.execute(request2, new FutureCallback<HttpResponse>() {
29.                            //Complete成功后会回调这个方法
30.                public void completed(final HttpResponse response2) {
31.                    System.out.println(request2.getRequestLine() + "->" + response2.getStatusLine());
32.                }
33.    
34.                public void failed(final Exception ex) {
35.                    System.out.println(request2.getRequestLine() + "->" + ex);
36.                }
37.    
38.                public void cancelled() {
39.                    System.out.println(request2.getRequestLine() + " cancelled");
40.                }
41.    
42.            });
43.        }
44.    }