我想用JobEnabledDecorator对象包装许多实现Job接口的类,该对象确定它是否执行.
我无法弄清楚如何在picocontainer中配置它,以便它知道用JobEnabledDecorator包装它们来创建Job实现对象.
这在依赖注入框架中是否可行?
picocontainer有可能吗?
如果是这样,任何帮助将不胜感激.
解决方法
你可能想要添加一个“行为”.简而言之,您需要注册一个行为工厂,它创建包装组件适配器的行为.通过一个例子来描述它更容易.
首先,你想要创建一个容器,就像这样.
final Mutablepicocontainer container = new PicoBuilder() .withBehaviors(new JobEnabledDecorating()) .build();
这意味着,一旦创建了基本对象 – 在您的情况下是作业 – 您想要添加额外的东西.有许多内置行为,但您需要自己的:JobEnabledDecorating.
public class JobEnabledDecorating extends AbstractBehaviorFactory { @Override public ComponentAdapter createComponentAdapter( final ComponentMonitor componentMonitor,final LifecycleStrategy lifecycleStrategy,final Properties componentProperties,final Object componentKey,final Class componentImplementation,final Parameter... parameters) throws PicoCompositionException { return componentMonitor.newBehavior( new JobEnabledDecorated( super.createComponentAdapter( componentMonitor,lifecycleStrategy,componentProperties,componentKey,componentImplementation,parameters ) ) ); } }
工厂通过包装组件适配器来创建JobEnabledDecorated行为,组件适配器又提供您的实例.现在真正的工作是在这种行为中完成的.
public class JobEnabledDecorated extends AbstractBehavior<Job> { public JobEnabledDecorated(final ComponentAdapter<Job> delegate) { super(delegate); } @Override public Job getComponentInstance(final picocontainer container,final Type into) throws PicoCompositionException { final Job instance = super.getComponentInstance(container,into); return new JobEnabledDecorator(instance); } @Override public String getDescriptor() { return "JobEnabledDecorator-"; } }
getComponentInstance要求作业,添加装饰器并将此包装对象作为新实例返回.你必须在这里添加你自己的逻辑.
public interface Job { void execute(); } public class JobEnabledDecorator implements Job { private Job delegate; public JobEnabledDecorator(final Job delegate) { this.delegate = delegate; } @Override public void execute() { System.out.println("before"); delegate.execute(); System.out.println("after"); } } public class MyJob implements Job { @Override public void execute() { System.out.println("execute"); } }
回到我们的容器用法,请考虑这个例子.
final Mutablepicocontainer container = new PicoBuilder() .withBehaviors(new JobEnabledDecorating()) .build(); container.addComponent(Job.class,MyJob.class); final Job job = container.getComponent(Job.class); job.execute();
运行此将打印:
before execute after
当然,这是因为容器交给你一个JobEnabledDecorator(MyJob)对象.
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