org.springframework.aop.target
Class AbstractLazyInitTargetSource

java.lang.Object
  org.springframework.aop.target.AbstractLazyInitTargetSource

All Implemented Interfaces:

TargetSource

public abstract class AbstractLazyInitTargetSource
extends Object
implements TargetSource

TargetSource that will lazy initialize a user-managed object.

Creation of the lazy target object is controlled by the user by implementing the createObject() method. This TargetSource will invoke this method the first time the proxy is accessed.

Useful when you need to pass a reference to some dependency to an object but you don't actually want the dependency to be created until it is first used. A typical scenario for this is a connection to a remote resource

Since:

1.2.4

Author:

Rob Harrop

See Also:

createObject()

Field Summary

protected org.apache.commons.logging.Log

logger Log instance for this class and sub-classes

Constructor Summary

AbstractLazyInitTargetSource()

Method Summary

protected abstract Object	createObject() Sub-classes should implement this method to return the lazy initialized object.
Object	getTarget() Returns the lazy-initialized target object, creating it if it doesn't exist.
Class	getTargetClass() Default implementation returns null if the target is null (it is hasn't yet been initialized) or the target class if the target has already been initialized.
boolean	isStatic() Will all calls to getTarget() return the same object?
void	releaseTarget(Object target) No need to release target - no op.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected final org.apache.commons.logging.Log logger

Log instance for this class and sub-classes

Constructor Detail

AbstractLazyInitTargetSource

public AbstractLazyInitTargetSource()

Method Detail

getTargetClass

public Class getTargetClass()

Default implementation returns null if the target is null (it is hasn't yet been initialized) or the target class if the target has already been initialized. Sub-classes may wish to override this method to provide more meaningful values when the target is still null.

Specified by:

getTargetClass in interface TargetSource

isStatic

public boolean isStatic()

Description copied from interface: TargetSource

Will all calls to getTarget() return the same object? In that case, there will be no need to invoke releaseTarget, and the AOP framework can cache the return value of getTarget().

Specified by:

isStatic in interface TargetSource

Returns:

whether the target is immutable

See Also:

TargetSource.getTarget()

getTarget

public Object getTarget()
                 throws Exception

Returns the lazy-initialized target object, creating it if it doesn't exist.

Specified by:

getTarget in interface TargetSource

Returns:

the target object, whicch contains the joinpoint

Throws:

Exception - if the target object can't be resolved

See Also:

createObject()

releaseTarget

public void releaseTarget(Object target)
                   throws Exception

No need to release target - no op.

Specified by:

releaseTarget in interface TargetSource

Parameters:

target - object obtained from a call to getTarget()

Throws:

Exception - if the object can't be released

See Also:

TargetSource.getTarget()

createObject

protected abstract Object createObject()
                                throws Exception

Sub-classes should implement this method to return the lazy initialized object. Called the first time the proxy is invoked.

Throws:

Exception