与RequestScope链接的本地线程 [英] Local Thread linked with RequestScope

问题描述

我有一个使用Capt的VRaptor构建的Web服务（焊接2.1.2.Final）。我需要并行处理服务器所做的一些处理（工业警报的统计分析）。我正在使用ExecutorService和Callable实例进行此操作，很遗憾，我的线程中需要一个请求范围依赖项。由于这种依赖性，我遇到了这个错误：

  WELD-001303：作用域类型javax.enterprise.context没有活动上下文.RequestScoped 
  

是否有一种方法可以将线程链接到使用CDI创建的请求？ / p>

*我知道我不应该在服务器中打开线程，但这是当前最可行的选择

解决方案

将其作为可调用对象的构造函数参数传递。

 公共类YourTask实现Callable< ; String> {
 
私人的YourData数据； 
 
 public YourTask（YourData data）{
 this.data = data; 
} 
 
 @Override 
 public String call（）{
 //只使用数据。 
} 
 
} 
  

  @注入
私有YourRequestScopedBean bean； 
 
 public void commit（）{
 YourTask task = new YourTask（bean.getData（））; 
 // ... 
} 
  

注意：请勿传递bean本身，因为它基本上是一个代理，其实例在其他线程中不存在。

另请参见：

• FacesContext.getCurrentInstance（）在Runnable中返回null类

---

无关问题是，即使通过正确编程的 ExecutorService 完成操作，也无法手动管理Java EE容器中的线程。它表明您不知道Java EE的EJB调度和计时器API的可能性。您可能会发现此答案中的示例很有用：在JSF托管的bean中启动新线程是否安全？

I have a web service built with VRaptor that uses CDI (weld 2.1.2.Final). I need to parallelize some of the processing made by the server (statistical analysis of industrial alarms). I'm doing that using a ExecutorService and Callable instances, unfortunately I need one Request Scoped dependence inside my Threads. Because of that dependence I'm facing this error:

WELD-001303: No active contexts for scope type javax.enterprise.context.RequestScoped

Is there a way to link the Threads to the Request where they were created using CDI?

*I know that I shouldn't be opening threads in the server, but this is the currently most viable option

解决方案

Pass it as constructor argument of the callable.

public class YourTask implements Callable<String> {

    private YourData data;

    public YourTask(YourData data) {
        this.data = data;
    }

    @Override
    public String call() {
        // Just use data.
    }

}

@Inject
private YourRequestScopedBean bean;

public void submit() {
    YourTask task = new YourTask(bean.getData());
    // ...
}

Note: do not pass the bean itself as it's basically a proxy whose instance doesn't exist in other thread.

See also:

• FacesContext.getCurrentInstance() returns null in Runnable class

---

Unrelated to the concrete problem, manually managing threads in a Java EE container, even though when done via a properly programmed ExecutorService, is frowned upon. It indicates you aren't aware of possibilities of Java EE's EJB scheduling and timer APIs. You may find the examples in this answer useful: Is it safe to start a new thread in a JSF managed bean?

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