JavaFX中的JavaBeanProperties没有引入java.desktop（Swing，AWT） [英] JavaBeanProperties in JavaFX without pulling in java.desktop (Swing, AWT)
问题描述
我有一些多次实例化的模型类，并且有许多字段。虽然我可以将所有字段初始化为 Simple * Property s，但由于分配（并且懒惰创建属性不是一个选项），这会显着降低性能。
I have some model classes that are instantiated many times and have many fields. While I could initialize all fields as Simple*Propertys, this significantly slows performance due to the allocations (and lazy-creating the properties is not an option).
因此，我更愿意使用 JavaBeanProperties 来创建应用程序中所需的按需绑定（如下所示）一个完整的示例 JavaBean包装与JavaFX属性）：
Thus, I would prefer to use JavaBeanProperties to create on-demand bindings where needed in the application like so (see this answer for a full example JavaBean wrapping with JavaFX Properties):
Entity bean = ...
StringProperty nameProperty = JavaBeanStringPropertyBuilder()
.bean(bean)
.name("name")
.build();
但是，我不想依赖 java.desktop module-info.java中的c $ c>和相关的Swing组件
However, I do not want to depend on java.desktop and related Swing components in my module-info.java
我可能会重写通过设置在每个Entity的set *方法上递增的SimpleIntegerProperty，然后在GUI中添加侦听器来实现所需的功能，但这仍然效率较低（不必要的更新）并且表达为使用 JavaBean * Property s
I could potentially re-write the desired functionality by setting a SimpleIntegerProperty that is incremented on each of the Entity's set* methods, and then add listeners in the GUI, but this is still less efficient (unnecessary updates) and expressive as using JavaBean*Propertys
如何在不使用java.desktop的情况下使用JavaBeanProperties（或类似的按需绑定功能）？
How may I use JavaBeanProperties (or similar on-demand binding functionality) without using java.desktop?
推荐答案
您可以使用完全不使用Reflection的通用解决方案：
You could use a generic solution that doesn’t use Reflection at all:
public class DelegatingProperty<B,T> extends ObjectPropertyBase<T>
implements JavaBeanProperty<T> {
/**
* Create a property without PropertyChangeEvent based notification.
*/
public static <O, V> JavaBeanProperty<V> get(O bean, String name,
Function<? super O, ? extends V> getter,
BiConsumer<? super O, ? super V> setter) {
return new DelegatingProperty<>(bean, name, getter, setter, null, null);
}
/**
* Create a property with PropertyChangeEvent based notification.
*/
public static <O, V> JavaBeanProperty<V> get(O bean, String name,
Function<? super O, ? extends V> getter, BiConsumer<? super O, ? super V> setter,
BiConsumer<? super O, ? super PropertyChangeListener> register,
BiConsumer<? super O, ? super PropertyChangeListener> unregister) {
return new DelegatingProperty<>(bean, name, getter, setter, register, unregister);
}
B bean;
String name;
Function<? super B, ? extends T> getter;
BiConsumer<? super B, ? super T> setter;
BiConsumer<? super B, ? super PropertyChangeListener> unregister;
PropertyChangeListener listener;
private DelegatingProperty(B bean, String name,
Function<? super B, ? extends T> getter,
BiConsumer<? super B, ? super T> setter,
BiConsumer<? super B, ? super PropertyChangeListener> register,
BiConsumer<? super B, ? super PropertyChangeListener> unregister) {
this.bean = Objects.requireNonNull(bean);
this.name = name;
this.getter = Objects.requireNonNull(getter);
this.setter = Objects.requireNonNull(setter);
if(register != null || unregister != null) {
Objects.requireNonNull(register);
this.unregister = Objects.requireNonNull(unregister);
register.accept(bean, listener = event -> fireValueChangedEvent());
}
}
@Override
public Object getBean() {
return bean;
}
@Override
public String getName() {
return name;
}
@Override
public T get() {
return getter.apply(bean);
}
@Override
public void set(T value) {
if(isBound()) throw new IllegalStateException("bound property");
T old = getter.apply(bean);
setter.accept(bean, value);
T now = getter.apply(bean);
if(!Objects.equals(old, now)) fireValueChangedEvent();
}
@Override
protected void invalidated() {
if(isBound()) {
setter.accept(bean, super.get());
}
}
@Override
public void fireValueChangedEvent() {
super.fireValueChangedEvent();
}
@Override
public void dispose() {
if(unregister != null && listener != null) {
unregister.accept(bean, listener);
listener = null;
}
}
}
然后，留在你的例如，您可以获得实体的名称属性为
Then, to stay at your example, you could get the name property of Entity as
JavaBeanProperty<String> prop = DelegatingProperty.get(bean, "name",
Entity::getName, Entity::setName,
Entity::addPropertyChangeListener, Entity::removePropertyChangeListener);
它更详细，但另一方面，提供更多的编译时安全性，因为所有的存在在编译时检查属性所需的方法，并且可能具有更高的运行时性能。
It’s more verbose, but on the other hand, provides more compile time safety, as the presence of all methods required for the property is checked at compile-time, and will likely have a higher runtime performance.
如果在一个具有事件支持的bean类中有很多属性，您可以从专用工厂方法中受益，例如
When you have a lot of properties in one bean class with event support, you may benefit from a dedicated factory method, e.g.
public static <V> JavaBeanProperty<V> property(Entity theBean, String name,
Function<? super Entity, ? extends V> getter,
BiConsumer<? super Entity, ? super V> setter) {
return DelegatingProperty.get(theBean, name, getter, setter,
Entity::addPropertyChangeListener, Entity::removePropertyChangeListener);
}
然后您可以将其用作
JavaBeanProperty<String> nameProp
= property(bean, "name", Entity::getName, Entity::setName);
JavaBeanProperty<String> otherProp
= property(bean, "other", Entity::getOther, Entity::setOther);
当然，也可以通过bean本身的实例方法提供它们而不是静态工厂方法，也许是一个持有该属性的延迟填充字段等。
Of course, it would also be possible to provide them via instance methods of the bean itself instead of a static factory method, too, perhaps with a lazily populated field holding the property, etc.
有几条路你可以从这个起点出发。
There are several roads you can go from this starting point.
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