Bean
The Bean EIP binds beans to Camel message exchanges.
URI Format
bean:beanID[?options]
Where beanID can be any string which is used to look up the bean in the Registry
EIP options
The Bean EIP supports 5 options which are listed below:
Name | Description | Default | Type |
---|---|---|---|
ref |
Sets a reference to a bean to use |
String |
|
method |
Sets the method name on the bean to use |
String |
|
beanType |
Sets the Class of the bean |
String |
|
cache |
Deprecated Use singleton option instead |
true |
Boolean |
scope |
Scope of bean. When using singleton scope (default) the bean is created or looked up only once and reused for the lifetime of the endpoint. The bean should be thread-safe in case concurrent threads is calling the bean at the same time. When using request scope the bean is created or looked up once per request (exchange). This can be used if you want to store state on a bean while processing a request and you want to call the same bean instance multiple times while processing the request. The bean does not have to be thread-safe as the instance is only called from the same request. When using prototype scope, then the bean will be looked up or created per call. However in case of lookup then this is delegated to the bean registry such as Spring or CDI (if in use), which depends on their configuration can act as either singleton or prototype scope. so when using prototype scope then this depends on the bean registry implementation. |
Singleton |
String |
Bean scope
When using singleton
scope (default) the bean is created or looked up only once and reused for the lifetime of the endpoint.
The bean should be thread-safe in case concurrent threads is calling the bean at the same time.
When using request
scope the bean is created or looked up once per request (exchange). This can be used if you want to store state on a bean
while processing a request and you want to call the same bean instance multiple times while processing the request.
The bean does not have to be thread-safe as the instance is only called from the same request.
When using prototype
scope, then the bean will be looked up or created per call. However in case of lookup then this is delegated
to the bean registry such as Spring or CDI (if in use), which depends on their configuration can act as either singleton or prototype scope.
so when using prototype
then this depends on the delegated registry.
Bean as endpoint
Camel also supports invoking Bean as an Endpoint. In the route below:
What happens is that when the exchange is routed to the myBean
Camel
will use the Bean Binding to invoke the bean.
The source for the bean is just a plain POJO:
Camel will use Bean Binding to invoke the
sayHello
method, by converting the Exchange’s In body to the String
type and storing the output of the method on the Exchange Out body.
Java DSL bean syntax
Java DSL comes with syntactic sugar for the Bean
component. Instead of specifying the bean explicitly as the endpoint
(i.e. to("bean:beanName")
) you can use the following syntax:
// Send message to the bean endpoint
// and invoke method resolved using Bean Binding.
from("direct:start").beanRef("beanName");
// Send message to the bean endpoint
// and invoke given method.
from("direct:start").beanRef("beanName", "methodName");
Instead of passing name of the reference to the bean (so that Camel will lookup for it in the registry), you can specify the bean itself:
// Send message to the given bean instance.
from("direct:start").bean(new ExampleBean());
// Explicit selection of bean method to be invoked.
from("direct:start").bean(new ExampleBean(), "methodName");
// Camel will create the instance of bean and cache it for you.
from("direct:start").bean(ExampleBean.class);
Bean binding
How bean methods to be invoked are chosen (if they are not specified explicitly through the method parameter) and how parameter values are constructed from the Message are all defined by the Bean Binding mechanism which is used throughout all of the various Bean Integration mechanisms in Camel.