Apache Camel POJO Bean Processor Singleton or Prototype?

问题

I'm using Camel's spring DSL to build routes and I'm using my POJO bean as a processor.

Initially, I as doing:

<bean ref="myPojoBeanProcessor"/>

where, 'myPojoBeanProcessor' was defined as a bean in my spring context.

Then, I switched to:

<bean beanType="com.mycompany.transformation.MyPojoBeanProcessor"/>

The Java DSL equivalent would be, I think:

from("xxx").bean(MyPojoBeanProcessor.class).xxx

I'm wondering if with the later approach, a bean object would be instantiated with every request or would the bean instance be cached and used as a singleton (like the default in spring).

I was unable to find an answer in the camel documentation or on google. Does anyone know the answer to this question?

回答1:

Why don't you just try it out :)

Camel will create an instance one time using the default no-arg constructor, and cache the instance, eg its singleton scoped.

回答2:

Here is the relevant piece of code in MethodCallExpression#createExpression(CamelContext):

if (this.beanType != null)
{
  Expression answer;
  if (ObjectHelper.hasDefaultPublicNoArgConstructor(this.beanType)) {
    this.instance = camelContext.getInjector().newInstance(this.beanType);
    answer = new BeanExpression(this.instance, getMethod());
  } else {
    answer = new BeanExpression(this.beanType, getMethod());
  }
}

Camel is caching the instance it creates in a field.

来源：https://stackoverflow.com/questions/10728029/apache-camel-pojo-bean-processor-singleton-or-prototype