Package org.springframework.aop.target

Class AbstractLazyCreationTargetSource

java.lang.Object
org.springframework.aop.target.AbstractLazyCreationTargetSource
All Implemented Interfaces:
TargetClassAware, TargetSource
public abstract class AbstractLazyCreationTargetSource extends Object implements TargetSource
TargetSource implementation that will lazily create 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, Juergen Hoeller
See Also:

  • Field Details

    • logger

      protected final Log logger
      Logger available to subclasses.

  • Constructor Details

    • AbstractLazyCreationTargetSource

      public AbstractLazyCreationTargetSource()

  • Method Details

    • isInitialized

      public boolean isInitialized()
      Return whether the lazy target object of this TargetSource has already been fetched.

    • getTargetClass

      @Nullable public Class<?> getTargetClass()
      This 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.

      Subclasses may wish to override this method in order to provide a meaningful value when the target is still null.

      Specified by:
      getTargetClass in interface TargetClassAware
      Specified by:
      getTargetClass in interface TargetSource
      Returns:
      the type of targets returned by this TargetSource
      See Also:

    • isStatic

      public boolean isStatic()
      Description copied from interface: TargetSource
      Will all calls to TargetSource.getTarget() return the same object?

      In that case, there will be no need to invoke TargetSource.releaseTarget(Object), and the AOP framework can cache the return value of TargetSource.getTarget().

      Specified by:
      isStatic in interface TargetSource
      Returns:
      true if the target is immutable
      See Also:

    • getTarget

      public Object getTarget() throws Exception
      Returns the lazy-initialized target object, creating it on-the-fly if it doesn't exist already.
      Specified by:
      getTarget in interface TargetSource
      Returns:
      the target object which contains the joinpoint, or null if there is no actual target instance
      Throws:
      Exception - if the target object can't be resolved
      See Also:

    • releaseTarget

      public void releaseTarget(Object target) throws Exception
      Description copied from interface: TargetSource
      Release the given target object obtained from the TargetSource.getTarget() method, if any.
      Specified by:
      releaseTarget in interface TargetSource
      Parameters:
      target - object obtained from a call to TargetSource.getTarget()
      Throws:
      Exception - if the object can't be released

    • createObject

      protected abstract Object createObject() throws Exception
      Subclasses should implement this method to return the lazy initialized object. Called the first time the proxy is invoked.
      Returns:
      the created object
      Throws:
      Exception - if creation failed