java - Cglib 方法拦截器是为每个类实例创建的吗？

Question

我有以下通用 cglib 方法拦截器实现:

public class EntityInterceptor<T, PK> implements MethodInterceptor{

    private EntityChangeType changeType;
    private T entity;
    private GenericCrudMapper<T,PK> mapper;

    public EntityInterceptor(T entity, GenericCrudMapper<T, PK> mapper){
        this.entity = entity;
        this.mapper = mapper;
    }

    @Override
    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
        // pass through
        return proxy.invoke(entity, args);
    }

    public void setEntityChangeType(EntityChangeType changeType){
        this.changeType = changeType;
    }

    public void saveChanges(){
        // @todo
    }

}

其用法如下:

@Override
    public Airport get(String id) {
        Airport airport = airportMapper.findById(id);
        if(airport != null){
            Enhancer enhancer = new Enhancer();
            enhancer.setSuperclass(Airport.class);
            enhancer.setCallback(new EntityInterceptor<>(airport, airportMapper));
            airport = (Airport) enhancer.create();
            return airport;
        }
        return airport;
    }

我可以安全地假设上面创建的方法拦截器将针对每个增强类实例进行实例化(换句话说，在分配方法拦截器时，它们不会在所有类实例之间共享)？

Answer 1

是的，这一点你可以确定。然而，您的解决方案效率相当低，因为为每个实例都会生成一个新类。相反，您应该根据拦截器类型创建代理:

// Do once
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(realObject.getClass());
enhancer.setCallbackType(Airport.class);
Class classForProxy = enhancer.createClass();

// Do for each instance
Enhancer.registerCallbacks(classForProxy, new Callback[]{new EntityInterceptor<>(airport, airportMapper});
Object createdProxy = classForProxy.newInstance();

这样您就可以为所有代理实例重用单个类。