Spring MVC 异步请求结合 Redis 发布订阅功能

Question

Spring Data Redis 配置

pom.xml ：

<!-- Spring Data Redis -->
<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-redis</artifactId>
  <version>2.2.8.RELEASE</version>
</dependency>

<dependency>
  <groupId>redis.clients</groupId>
  <artifactId>jedis</artifactId>
  <version>3.1.0</version>
</dependency>
<!-- ./Spring Data Redis -->

app-context.xml ：

<!-- 配置 Jedis 连接器 -->
<bean class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
  p:hostName="127.0.0.1" p:port="6379" p:usePool="true"/>

<bean class="org.springframework.data.redis.core.RedisTemplate"
  p:connection-factory-ref="jedisConnectionFactory"/>

<!-- 消息发布/订阅 -->
<redis:listener-container connection-factory="jedisConnectionFactory">
  <!-- the method attribute can be skipped as the default method name is "handleMessage" -->
  <redis:listener ref="newsListener" method="handleMessage" topic="news" />
</redis:listener-container>

<bean class="net.wuxianjie.demo.redis.NewsMessageDelegate"/>
<!-- ./消息发布/订阅 -->
<!-- ./配置 Jedis 连接器 -->

package net.wuxianjie.demo.redis;

public interface MessageDelegate {

  void handleMessage(String message);
}

package net.wuxianjie.demo.redis;

import org.springframework.web.context.request.async.DeferredResult;

public class NewsMessageDelegate implements MessageDelegate {

  private DeferredResult<String> deferredResult;

  @Override
  public void handleMessage(String message) {

    deferredResult.setResult(message);
  }

  public DeferredResult<String> getDeferredResult() {
    return deferredResult;
  }

  public void setDeferredResult(
    DeferredResult<String> deferredResult) {
    this.deferredResult = deferredResult;
  }
}

测试代码

package net.wuxianjie.demo.controller;

import net.wuxianjie.demo.redis.NewsMessageDelegate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.context.request.async.DeferredResult;

@RestController
@RequestMapping("/news")
public class NewsController {

  @Autowired
  private NewsMessageDelegate newsMessageDelegate;

  @GetMapping("")
  public DeferredResult<String> getNews() {

    DeferredResult<String> deferredResult = new DeferredResult<>(3000L);

    newsMessageDelegate.setDeferredResult(deferredResult);

    deferredResult.onTimeout(() -> {
      deferredResult.setResult("请求超时");
    });

    return deferredResult;
  }
}

如果在请求的 3 秒内， news 频道有消息发布，则立即获取此消息；否则，返回 "请求超时" ：

GET http://localhost:8000/news

通过 redis-cli 向 news 频道发布消息：

127.0.0.1:6379> publish news hello