java异步支持未启用,即使默认情况下应该启用
我有一个用spring boot和google应用程序引擎构建的应用程序。我已经尝试通过遵循本https://golb.hplar.ch/p/Server-Sent-Events-with-Spring教程来实现sever sent事件。 当我构建并尝试访问创建sse发射器的端点时,我得到以下错误
java.lang.IllegalStateException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml.
这很奇怪,因为spring boot应该在默认情况下启用异步支持https://github.com/spring-projects/spring-boot/issues/1665,正如本期中所述
我已经尝试添加一些stackoverflow线程上建议的以下代码,但仍然存在相同的问题。有办法避免这个错误吗
@Bean
public ServletRegistrationBean dispatcherServlet() {
ServletRegistrationBean registration = new
ServletRegistrationBean(new DispatcherServlet(), "/");
registration.setAsyncSupported(true);
return registration;
}
值得补充的是,我在尝试实现WebSocket时遇到了同样的问题,后来我放弃了WebSocket,转而支持服务器发送的事件。 代码如下:
波姆。xml
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<!-- Exclude Tomcat so that it doesn't conflict w/ Jetty server -->
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>1.9.54</version>
</dependency>
<dependency> <!-- Google Core Libraries for Java -->
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId> <!-- https://github.com/google/guava/wiki -->
<!-- Guava v21.0 doesn't support Java7 -->
<version>20.0</version>
<scope>compile</scope>
</dependency>
<dependency> <!-- Google Cloud Client Library for Java -->
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-storage</artifactId>
<version>1.3.1</version>
</dependency>
<!-- Exclude any jul-to-slf4j -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jul-to-slf4j</artifactId>
<scope>provided</scope>
</dependency>
<!-- Include Servlet API -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-datastore</artifactId>
<version>1.4.0</version>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
<version>1.5.8.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.security.oauth</groupId>
<artifactId>spring-security-oauth2</artifactId>
<version>2.2.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.social</groupId>
<artifactId>spring-social-core</artifactId>
<version>1.1.4.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.session</groupId>
<artifactId>spring-session</artifactId>
<version>1.3.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.18</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.webjars.bower</groupId>
<artifactId>jquery</artifactId>
<version>2.1.3</version>
</dependency>
<dependency>
<groupId>org.webjars</groupId>
<artifactId>bootstrap</artifactId>
<version>3.3.1</version>
</dependency>
</dependencies>
Java代码:
@SpringBootApplication
@EnableOAuth2Sso
public class SpringBootExampleApplication extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http.csrf().csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse())
.and()
.authorizeRequests()
.anyRequest() // This is just temporary. Otherwise only "/" is permited
.permitAll();
}
public static void main(String[] args) {
SpringApplication.run(SpringBootExampleApplication.class, args);
}
}
控制员:
@Controller
public class SSEController {
private final CopyOnWriteArrayList<SseEmitter> emitters = new CopyOnWriteArrayList<>();
@GetMapping("/memory")
public SseEmitter handle() {
SseEmitter emitter = new SseEmitter();
// SseEmitter emitter = new SseEmitter(180_000L);
this.emitters.add(emitter);
emitter.onCompletion(() -> this.emitters.remove(emitter));
emitter.onTimeout(() -> this.emitters.remove(emitter));
return emitter;
}
@EventListener
public void onMemoryInfo(MemoryInfo memoryInfo) {
List<SseEmitter> deadEmitters = new ArrayList<>();
this.emitters.forEach(emitter -> {
try {
emitter.send(memoryInfo);
}
catch (Exception e) {
deadEmitters.add(emitter);
}
});
this.emitters.removeAll(deadEmitters);
}
}
定期服务:
@Service
public class MemoryObserverJob {
public final ApplicationEventPublisher eventPublisher;
public MemoryObserverJob(ApplicationEventPublisher eventPublisher) {
this.eventPublisher = eventPublisher;
}
@Scheduled(fixedRate = 1000)
public void doSomething() {
MemoryInfo mi = new MemoryInfo(123L, 123L);
this.eventPublisher.publishEvent(mi);
}
}
邮件的模板:
public class MemoryInfo {
private final long heap;
private final long nonHeap;
private final long ts;
public MemoryInfo(long heap, long nonHeap) {
this.ts = System.currentTimeMillis();
this.heap = heap;
this.nonHeap = nonHeap;
}
public long getHeap() {
return this.heap;
}
public long getNonHeap() {
return this.nonHeap;
}
public long getTs() {
return this.ts;
}
}
# 1 楼答案
用@EnableAsync注释引导应用程序
然后向您想要异步的方法添加另一个