Bean Method

Since Camel 1.3

The Bean language is used for calling a method on an existing Java bean.

Camel adapts to the method being called via Bean Binding. The binding process will, for example, automatically convert the message payload to the parameter of type of the first parameter in the method. The binding process has a lot more features, so it is recommended to read the Bean Binding documentation for mor details.

Bean Method options

The Bean Method language supports 7 options, which are listed below.

Name Default Java Type Description

ref (common)

String

Reference to an existing bean (bean id) to lookup in the registry.

method (common)

String

Name of method to call.

beanType (common)

String

Class name (fully qualified) of the bean to use Will lookup in registry and if there is a single instance of the same type, then the existing bean is used, otherwise a new bean is created (requires a default no-arg constructor).

scope (advanced)

Singleton

Enum

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.

Enum values:

  • Singleton

  • Request

  • Prototype

validate (advanced)

true

Boolean

Whether to validate the bean has the configured method.

resultType (common)

String

Sets the class of the result type (type from output).

trim (advanced)

true

Boolean

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

Examples

In the given route below, we call a Java Bean Method with method, where "myBean" is the id of the bean to use (lookup from Registry), and "isGoldCustomer" is the name of the method to call.

  • Java

  • XML

from("activemq:topic:OrdersTopic")
  .filter().method("myBean", "isGoldCustomer")
    .to("activemq:BigSpendersQueue");

It is also possible to omit the method name. In this case, then Camel would choose the best suitable method to use. This process is complex, so it is good practice to specify the method name.

 
<route>
  <from uri="activemq:topic:OrdersTopic"/>
  <filter>
    <method ref="myBean" method="isGoldCustomer"/>
    <to uri="activemq:BigSpendersQueue"/>
  </filter>
</route>

The bean could be implemented as follows:

public class MyBean {
  public boolean isGoldCustomer(Exchange exchange) {
     // ...
  }
}

How this method uses Exchange in the method signature. You would often not do that, and use non-Camel types. For example, by using String then Camel will automatically convert the message body to this type when calling the method:

public boolean isGoldCustomer(String body) {...}

Using Annotations for bean integration

You can also use the Bean Integration annotations, such as @Header, @Body, @Variable etc

public boolean isGoldCustomer(@Header(name = "foo") Integer fooHeader) {...}

So you can bind parameters of the method to the Exchange, the Message or individual headers, properties, the body or other expressions.

Non-Registry Beans

The Bean Method Language also supports invoking beans that are not registered in the Registry.

Camel can instantiate the bean of a given type and invoke the method or invoke the method on an already existing instance.

from("activemq:topic:OrdersTopic")
  .filter().method(MyBean.class, "isGoldCustomer")
  .to("activemq:BigSpendersQueue");

The first parameter can also be an existing instance of a Bean such as:

private MyBean my = ...;

from("activemq:topic:OrdersTopic")
  .filter().method(my, "isGoldCustomer")
  .to("activemq:BigSpendersQueue");

Spring Boot Auto-Configuration

When using bean with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-bean-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 14 options, which are listed below.

Name Description Default Type

camel.component.bean.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.bean.bean-info-cache-size

Maximum cache size of internal cache for bean introspection. Setting a value of 0 or negative will disable the cache.

1000

Integer

camel.component.bean.enabled

Whether to enable auto configuration of the bean component. This is enabled by default.

Boolean

camel.component.bean.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean

camel.component.bean.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 delegate 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.

singleton

BeanScope

camel.component.class.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.class.bean-info-cache-size

Maximum cache size of internal cache for bean introspection. Setting a value of 0 or negative will disable the cache.

1000

Integer

camel.component.class.enabled

Whether to enable auto configuration of the class component. This is enabled by default.

Boolean

camel.component.class.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean

camel.component.class.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 delegate 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.

singleton

BeanScope

camel.language.bean.enabled

Whether to enable auto configuration of the bean language. This is enabled by default.

Boolean

camel.language.bean.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

camel.language.bean.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.bean.validate

Whether to validate the bean has the configured method.

true

Boolean
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