Delegated Dynamic Properties

The previous two sections showed what dynamic properties are and how to use them simply. The most powerful part of dynamic properties is delegated property values.

tip

Delegating a property value means that when the program calls the property's get/set methods, the method call is mapped to a corresponding interface. Reading and writing the property is implemented entirely by that interface.

public interface PropertyDelegate {
    /** The get method of this delegated property. The parameter is the object that owns the property. */
    public Object get(Object target) throws Throwable;

    /** The set method of this delegated property. The first parameter is the owning object, and the second is the new value. */
    public void set(Object target, Object newValue) throws Throwable;
}

A typical use case is sharing the same property between multiple beans:

// Register two beans and share the same name property.
AppContext appContext = Hasor.create().build(apiBinder -> {
    SimplePropertyDelegate delegate = new SimplePropertyDelegate("helloWord");
    apiBinder.bindType(PojoBean1.class).dynamicProperty("name", String.class, delegate);
    apiBinder.bindType(PojoBean2.class).dynamicProperty("name", String.class, delegate);
});

// Create two beans.
PojoBean1 pojoBean1 = appContext.getInstance(PojoBean1.class);
PojoBean2 pojoBean2 = appContext.getInstance(PojoBean2.class);
//
assert BeanUtils.readProperty(pojoBean1, "name").equals("helloWord");
assert BeanUtils.readProperty(pojoBean2, "name").equals("helloWord");
BeanUtils.writeProperty(pojoBean1, "name", "newValue");
assert BeanUtils.readProperty(pojoBean1, "name").equals("newValue");
assert BeanUtils.readProperty(pojoBean2, "name").equals("newValue");