动态代理接口并注册到spring容器

实现将一个接口动态代理，并将该代理对象在spring容器初始化完成前注册到spring容器中。实现可以通过@Autowired等注释或其他方法从spring容器中获取该代理对象。

2、灵感来源

翻mybatis的源代码获得，

源代码下载

3.1、接口类

public interface TestService {

public String sayHello();
}

3.2、代理类

public class MyProxy implements InvocationHandler{

private Class<?> interfaceClass;

public Object bind(Class<?> cls) {
		this.interfaceClass = cls;
		return Proxy.newProxyInstance(cls.getClassLoader(), new Class[] {interfaceClass}, this);
	}

@Override
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		return "hello world";
	}

}

3.3、代理工厂

public class MyProxyFactory<T> implements FactoryBean<T> {

private Class<T> interfaceClass;
	public Class<T> getInterfaceClass() {
		return interfaceClass;
	}
	public void setInterfaceClass(Class<T> interfaceClass) {
		this.interfaceClass = interfaceClass;
	}
	@Override
	public T getObject() throws Exception {
		return (T) new MyProxy().bind(interfaceClass);
	}

@Override
	public Class<?> getObjectType() {
		return interfaceClass;
	}

@Override
	public boolean isSingleton() {
		// 单例模式
		return true;
	}

}

3.4、注册spring容器

@Component
public class MyRegistryBean implements ApplicationContextAware,BeanDefinitionRegistryPostProcessor{

private ApplicationContext ctx;
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
	}
	@Override
	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
		// 需要被代理的接口
		Class<?> cls = TestService.class;
		BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(cls);
		GenericBeanDefinition definition = (GenericBeanDefinition) builder.getRawBeanDefinition();
		definition.getPropertyValues().add("interfaceClass", definition.getBeanClassName());
		definition.setBeanClass(MyProxyFactory.class);
		definition.setAutowireMode(GenericBeanDefinition.AUTOWIRE_BY_TYPE);
		// 注册bean名,一般为类名首字母小写
		beanDefinitionRegistry.registerBeanDefinition("testService", definition);
	}
	@Override
	public void setApplicationContext(ApplicationContext ctx) throws BeansException {
		this.ctx = ctx;
	}

}

3.5、测试

@RunWith(SpringJUnit4ClassRunner.class)  
@ContextConfiguration({"classpath*:applicationContext.xml"})  
public class Start {

@Autowired
	TestService testService;

@Test
	public void test() {
		System.out.println(testService.sayHello());
	}
}

控制台成功输出“hello world”，即成功在spring容器初始化完成前，将TestService接口代理，并将代理类注册到spring容器中。