The execution context of a Handler execution.
处理程序的执行上下文.
When Vert.x provides an event to a handler or calls the start or stop methods of a Verticle, the execution is associated with a Context.
当Vert.x向处理程序提供事件或调用 Verticle 的start或stop方法时，执行与 Context关联。
Usually a context is an event-loop context and is tied to a specific event loop thread. So executions for that context always occur on that exact same event loop thread. 通常，上下文是事件循环上下文，并绑定到特定的事件循环线程。因此，该上下文的执行始终发生在完全相同的事件循环线程上。
In the case of worker verticles and running inline blocking code a worker context will be associated with the execution which will use a thread from the worker thread pool. 在工作线程和运行内联阻塞代码的情况下，工作线程上下文将与执行相关联，该执行将使用工作线程池中的线程。
When a handler is set by a thread associated with a specific context, the Vert.x will guarantee that when that handler is executed, that execution will be associated with the same context. 当处理程序由与特定上下文关联的线程设置时，Vert.x将保证当执行该处理程序时，该执行将与相同的上下文关联。
If a handler is set by a thread not associated with a context (i.e. a non Vert.x thread). Then a new context will be created for that handler. 如果处理程序是由与上下文不关联的线程设置的（即非Vert.x线程）。 然后将为该处理程序创建一个新的上下文。
In other words, a context is propagated. 换句话说，上下文被传播。
This means that when a verticle is deployed, any handlers it sets will be associated with the same context - the context of the verticle. 这意味着，当部署一个 verticle 时，其设置的任何处理程序都将与相同的上下文相关联 - verticle 的上下文。
This means (in the case of a standard verticle) that the verticle code will always be executed with the exact same thread, so you don't have to worry about multi-threaded acccess to the verticle state and you can code your application as single threaded. 这意味着(在标准verticle的情况下), verticle代码将始终使用完全相同的线程执行，因此您不必担心对verticle状态的多线程访问，并且可以将应用程序编码为单线程。
This class also allows arbitrary data to be put(java.lang.Object, java.lang.Object) and get(java.lang.Object) on the context so it can be shared easily amongst different handlers of, for example, a verticle instance.
这个类还允许将任意数据 put(java.lang。Object, java.lang.Object) 和 get(java.lang.Object) 放在上下文上，因此它可以在不同的处理程序之间轻松共享，例如，一个verticle实例。
This class also provides runOnContext(io.vertx.core.Handler) which allows an action to be executed asynchronously using the same context.
这个类还提供了 runOnContext(io. vertex .core. handler) ，它允许使用相同的上下文异步执行操作。