技术要点
org.springframework.web.context.request.async.DeferredResult<T>
示例如下：
1. 新建Maven项目 async
2. pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion>
<groupId>com.java</groupId>
<artifactId>async</artifactId>
<version>1.0.0</version> <parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.5.RELEASE</version>
</parent> <dependencies> <!-- Spring Boot -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency> <!-- 热部署 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>springloaded</artifactId>
<version>1.2.8.RELEASE</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>provided</scope>
</dependency> </dependencies> <build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin> <plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
3. AsyncStarter.java
package com.java; import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication
public class AsyncStarter { public static void main(String[] args) {
SpringApplication.run(AsyncStarter.class, args);
} }
4. AsyncVo.java
package com.java.vo; import org.springframework.web.context.request.async.DeferredResult; /**
* 存储异步处理信息
*
* @author Logen
*
* @param <I> 接口输入参数
* @param <O> 接口返回参数
*/
public class AsyncVo<I, O> { /**
* 请求参数
*/
private I params; /**
* 响应结果
*/
private DeferredResult<O> result; public I getParams() {
return params;
} public void setParams(I params) {
this.params = params;
} public DeferredResult<O> getResult() {
return result;
} public void setResult(DeferredResult<O> result) {
this.result = result;
} }
5. RequestQueue.java
package com.java.queue; import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue; import org.springframework.stereotype.Component; import com.java.vo.AsyncVo; /**
* 存放所有异步处理接口请求队列的对象,一个接口对应一个队列
*
* @author Logen
*
*/
@Component
public class RequestQueue { /**
* 处理下订单接口的队列，设置缓冲容量为50
*/
private BlockingQueue<AsyncVo<String, Object>> orderQueue = new LinkedBlockingQueue<>(50); public BlockingQueue<AsyncVo<String, Object>> getOrderQueue() {
return orderQueue;
} }
6. OrderTask.java
package com.java.task; import java.util.HashMap;
import java.util.Map; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component; import com.java.queue.RequestQueue;
import com.java.vo.AsyncVo; /**
* 处理订单接口的任务，每个任务类处理一种接口
*
* @author Logen
*
*/
@Component
public class OrderTask extends Thread { @Autowired
private RequestQueue queue; private boolean running = true; @Override
public void run() {
while (running) {
try {
AsyncVo<String, Object> vo = queue.getOrderQueue().take();
System.out.println("[ OrderTask ]开始处理订单"); String params = vo.getParams();
Thread.sleep(3000);
Map<String, Object> map = new HashMap<>();
map.put("params", params);
map.put("time", System.currentTimeMillis()); vo.getResult().setResult(map); System.out.println("[ OrderTask ]订单处理完成");
} catch (InterruptedException e) {
e.printStackTrace();
running = false;
} }
} public void setRunning(boolean running) {
this.running = running;
} }
7. QueueListener.java
package com.java.listener; import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component; import com.java.task.OrderTask; /**
* 队列监听器，初始化启动所有监听任务
*
* @author Logen
*
*/
@Component
public class QueueListener { @Autowired
private OrderTask orderTask; /**
* 初始化时启动监听请求队列
*/
@PostConstruct
public void init() {
orderTask.start();
} /**
* 销毁容器时停止监听任务
*/
@PreDestroy
public void destory() {
orderTask.setRunning(false);
} }
8. OrderController.java
package com.java.controller; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.context.request.async.DeferredResult; import com.java.queue.RequestQueue;
import com.java.vo.AsyncVo; /**
* <blockquote>
*
* <pre>
*
* 模拟下单处理，实现高吞吐量异步处理请求
*
* 1、 Controller层接口只接收请求，不进行处理，而是把请求信息放入到对应该接口的请求队列中
* 2、 该接口对应的任务类监听对应接口的请求队列，从队列中顺序取出请求信息并进行处理
*
* 优点：接口几乎在收到请求的同时就已经返回，处理程序在后台异步进行处理，大大提高吞吐量
*
*
* </pre>
*
* </blockquote>
*
* @author Logen
*
*/
@RestController
public class OrderController { @Autowired
private RequestQueue queue; @GetMapping("/order")
public DeferredResult<Object> order(String number) throws InterruptedException {
System.out.println("[ OrderController ] 接到下单请求");
System.out.println("当前待处理订单数： " + queue.getOrderQueue().size()); AsyncVo<String, Object> vo = new AsyncVo<>();
DeferredResult<Object> result = new DeferredResult<>(); vo.setParams(number);
vo.setResult(result); queue.getOrderQueue().put(vo);
System.out.println("[ OrderController ] 返回下单结果");
return result;
} }
9. 运行 AsyncStarter.java ，启动测试
浏览器输入 http://localhost:8080/order?number=10001
正常情况处理3秒返回，返回结果如下
{"time":1548241500718,"params":"10001"}
观察控制台打印日志，如下所示：
[ OrderController ] 接到下单请求
当前待处理订单数： 0
[ OrderController ] 返回下单结果
[ OrderTask ]开始处理订单
[ OrderTask ]订单处理完成
结论：Controller层几乎在接收到请求的同时就已经返回，处理程序在后台异步处理任务。
快速多次刷新浏览器，目的为了高并发测试，观察控制台打印信息
现象：Controller层快速返回，待处理请求在队列中开始增加，异步处理程序在按顺序处理请求。
优点：对客户端响应时间不变，但提高了服务端的吞吐量。大大提升高并发处理性能！
.
