TargetSource (Spring Framework 5.2.12.RELEASE API)

所有超级接口:
TargetClassAware
所有已知实现类:
AbstractBeanFactoryBasedTargetSource, AbstractLazyCreationTargetSource, AbstractPoolingTargetSource, AbstractPrototypeBasedTargetSource, AbstractRefreshableTargetSource, BeanFactoryRefreshableTargetSource, CommonsPool2TargetSource, EmptyTargetSource, HotSwappableTargetSource, JndiObjectTargetSource, LazyInitTargetSource, PrototypeTargetSource, RefreshableScriptTargetSource, SimpleBeanTargetSource, SingletonTargetSource, ThreadLocalTargetSource
```
public interface TargetSource
extends TargetClassAware
```
A TargetSource is used to obtain the current "target" of an AOP invocation, which will be invoked via reflection if no around advice chooses to end the interceptor chain itself.
If a TargetSource is "static", it will always return the same target, allowing optimizations in the AOP framework. Dynamic target sources can support pooling, hot swapping, etc.
Application developers don't usually need to work with TargetSources directly: this is an AOP framework interface.
作者:
Rod Johnson, Juergen Hoeller

方法概要

所有方法实例方法抽象方法
修饰符和类型	方法	说明
`Object`	`getTarget()`	Return a target instance.
`Class<?>`	`getTargetClass()`	Return the type of targets returned by this `TargetSource`.
`boolean`	`isStatic()`	Will all calls to `getTarget()` return the same object?
`void`	`releaseTarget(Object target)`	Release the given target object obtained from the `getTarget()` method, if any.

- 方法详细资料
  - getTargetClass
```
@Nullable
Class<?> getTargetClass()
```
    Return the type of targets returned by this TargetSource.
    Can return null, although certain usages of a TargetSource might just work with a predetermined target class.
    指定者:
    getTargetClass 在接口中 TargetClassAware
    返回:
    the type of targets returned by this TargetSource
  - isStatic
```
boolean isStatic()
```
    Will all calls to getTarget() return the same object?
    In that case, there will be no need to invoke releaseTarget(Object), and the AOP framework can cache the return value of getTarget().
    返回:
    true if the target is immutable
    另请参阅:
    getTarget()
  - getTarget
```
@Nullable
Object getTarget()
          throws Exception
```
    Return a target instance. Invoked immediately before the AOP framework calls the "target" of an AOP method invocation.
    返回:
    the target object which contains the joinpoint, or null if there is no actual target instance
    抛出:
    Exception - if the target object can't be resolved
  - releaseTarget
```
void releaseTarget(Object target)
            throws Exception
```
    Release the given target object obtained from the getTarget() method, if any.
    参数:
    target - object obtained from a call to getTarget()
    抛出:
    Exception - if the object can't be released