从ObjectProperty更新事件(就像在ObservableList中一样)

如果值 SomeType#property 改变,但如果 SomeType#property#testProperty 变化。

我不能只听 SomeType#property#testProperty ,因为我不会被通知,当 SomeType#属性

这是JavaFX当前迭代的一个限制。内置方式不可靠,最好使用第三方库。看到这个了吗 answer 了解更多信息。

对于您的情况,可以以类似的方式使用ReactFX:

import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;

import org.reactfx.value.Val;
import org.reactfx.value.Var;

class TestBean {

    private final StringProperty testProperty = new SimpleStringProperty();
    public final StringProperty testPropertyProperty()        { return testProperty; }
    public final String getTestProperty()                     { return testProperty.get(); }
    public final void setTestProperty(String newTestProperty) { testProperty.set(newTestProperty); }
}

public class SomeType {

    private final ObjectProperty<TestBean> property = new SimpleObjectProperty<>();
    public final ObjectProperty<TestBean> propertyProperty() { return property; }
    public final TestBean getProperty()                      { return property.get(); }
    public final void setProperty(TestBean newProperty)      { property.set(newProperty); }

    public static void main(String[] args) {
        SomeType someType = new SomeType();
        Var<String> chainedTestProperty = Val.selectVar(someType.propertyProperty(), TestBean::testPropertyProperty);
        chainedTestProperty.addListener((obs, oldVal, newVal) -> System.out.println(obs + " " + oldVal + "->" + newVal));

        //Tests
        someType.setProperty(new TestBean());
        someType.getProperty().setTestProperty("s1");
        TestBean bean2 = new TestBean();
        bean2.setTestProperty("s2");
        someType.setProperty(bean2);
        someType.setProperty(new TestBean());
    }
}

输出:

org.reactfx.value.FlatMappedVar@7aec35a null->s1 
org.reactfx.value.FlatMappedVar@7aec35a s1->s2 
org.reactfx.value.FlatMappedVar@7aec35a s2->null

关键线路

Var<String> chainedTestProperty = Val.selectVar(someType.propertyProperty(), TestBean::testPropertyProperty);

是一种侦听器链接。第一个参数是一个属性( OvservableValue )某种类型的 Type Type2 在…内 类型 到那个地方。

现在,无论何时链中的任何“链接”发生变化,都会通知您。通过这种方式连续链接ovservables,您可以继续侦听sub-sub属性中的更改。

public class ObservableValueProperty<T> extends SimpleObjectProperty<T> {

    private InvalidationListener listener = null;

    private final Callback<T, Observable[]> extractor;

    public ObservableValueProperty() {
    this(null);
    }

    public ObservableValueProperty(final Callback<T, Observable[]> extractor) {
    this.extractor = extractor;
    }

    @Override
    protected void fireValueChangedEvent() {
    super.fireValueChangedEvent();
    }

    @Override
    public void setValue(final T v) {
    if (extractor != null) {
        final T oldValue = super.get();
        if (oldValue != null) {
        for (final Observable o : extractor.call(oldValue)) {
            o.removeListener(listener);
        }
        }
        listener = o -> fireValueChangedEvent();
        for (final Observable o : extractor.call(v)) {
        o.addListener(listener);
        }
    }
    super.setValue(v);
    }
}

public class ObservableValuePropertyTest4 implements ChangeListener<Object> {

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
    }

    @AfterClass
    public static void tearDownAfterClass() throws Exception {
    }

    @Before
    public void setUp() throws Exception {
    }

    @After
    public void tearDown() throws Exception {
    }

    static class NestedBean {

    StringProperty nestedProperty = new SimpleStringProperty("hans");

    public static <T extends NestedBean> Callback<T, Observable[]> extractor() {

        return (final T o) -> new Observable[] { o.nestedProperty };
    }

    @Override
    public boolean equals(final Object obj) {
        if (obj instanceof NestedBean) {
        System.err.println(this.nestedProperty.get() + " " + ((NestedBean) obj).nestedProperty.get());
        return Objects.equal(this.nestedProperty.get(), ((NestedBean) obj).nestedProperty.get());
        }
        return false;
    }

    }

    private ObservableValueProperty<NestedBean> p;

    private NestedBean nestedBean;

    private String newNestedValue = null;

    @Test
    public void test01() {
    p = new ObservableValueProperty<>(NestedBean.extractor());
    nestedBean = new NestedBean();
    p.setValue(nestedBean);
    p.addListener(this);
    nestedBean.nestedProperty.set("peter");
    assertEquals("peter", newNestedValue);
    }

    @Override
    public void changed(final ObservableValue<? extends Object> observable, final Object oldValue,
        final Object newValue) {
    System.err.println("Changed");
    newNestedValue = nestedBean.nestedProperty.get();

    }

}

不幸的是,这不会引发任何更改事件,因为 ExpressionHelper$SingleChange :

@Override
        protected void fireValueChangedEvent() {
            final T oldValue = currentValue;
            currentValue = observable.getValue();
            final boolean changed = (currentValue == null)? (oldValue != null) : !currentValue.equals(oldValue);
            if (changed) {
                try {
                    listener.changed(observable, oldValue, currentValue);
                } catch (Exception e) {
                    Thread.currentThread().getUncaughtExceptionHandler().uncaughtException(Thread.currentThread(), e);
                }
            }
        }

这将检查是否相等,并且仅当不相等时,才通知所有侦听器。当我触发时 fireValueChangedEvent() 该值已更改,并且新值和旧值相等,因此不会通知侦听器。

• 我创建了一个名为 ObjectXProperty<E> ObjectProperty<E>
• 它具有可以接受 Callback<E,Observable[]> ,我们的提取器功能;
• 内部 ObjectXProperty SimpleObjectProperty 这削弱了所有方法;

• 魔术在于 set(E value) 方法:我创建一个 ObjectBinding 只需将 ,但它使用提取器函数来决定何时失效!

• 如果 bind 方法之前在 ,让“真正的”装订完成他的工作;如果 unbind 方法被调用;

这是我的新课 :

import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.beans.binding.Bindings;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.util.Callback;

/**
 *
 * @author Claude Bouchard - 2017
 */

public class ObjectXProperty<E> extends ObjectProperty<E> {

SimpleObjectProperty<E> p;
Callback<E, Observable[]> extractor;

boolean externalBound = false;

public ObjectXProperty(Callback<E, Observable[]> extractor) {
    this.extractor = extractor;
}

public ObjectXProperty(E init, Callback<E, Observable[]> extractor) {

    p = new SimpleObjectProperty();
    this.extractor = extractor;
    set(init);

}

public ObjectXProperty(Object bean, String name, Callback<E, Observable[]> extractor) {
    p = new SimpleObjectProperty(bean, name);
    this.extractor = extractor;
}

public ObjectXProperty(Object bean, String name, E init, Callback<E, Observable[]> extractor) {
    p = new SimpleObjectProperty(bean, name);
    this.extractor = extractor;
    set(init);

}

@Override
public void set(E value) {
    if (!externalBound) {
        if (value != null) {
            p.bind(Bindings.createObjectBinding(() -> {
                return value;
            }, extractor.call(value)));

        } else {
            p.bind(Bindings.createObjectBinding(() -> {
                return value;
            }, new Observable[]{}));
        }
    } else {
        p.set(value); //As expected, it will throw a java.lang.RuntimeException
    }
}

@Override
public E get() {
    return p.get();
}

@Override
public void addListener(ChangeListener<? super E> listener) {
    p.addListener(listener);
}

@Override
public void removeListener(ChangeListener<? super E> listener) {
    p.removeListener(listener);
}

@Override
public void addListener(InvalidationListener listener) {
    p.addListener(listener);
}

@Override
public void removeListener(InvalidationListener listener) {
    p.removeListener(listener);
}

@Override
public Object getBean() {
    return p.getBean();
}

@Override
public String getName() {
    return p.getName();
}

@Override
public void bind(ObservableValue<? extends E> observable) {
    p.bind(observable);
    externalBound = true;
}

@Override
public void unbind() {
    p.unbind();
    externalBound = false;
    set(get()); //to reactivate the extractor on the last value
}

@Override
public boolean isBound() {
    return externalBound;
}

}

我认为你需要给你的对象添加一个监听器。这可以简单地做到。首先,您应该用构造函数和getter这样编写类:

import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;

public class SomeType {

    public ObjectProperty<TestProperty> property;

    public SomeType(TestProperty testProperty) {
        this.property = new SimpleObjectProperty<>(testProperty);
    }

    public TestProperty getProperty() {
        return property.get();
    }

    public ObjectProperty<TestProperty> propertyProperty() {
        return property;
    }
}

SomeType property 该物业的 testProperty()

someType.getProperty().testProperty().addListener((observable, oldValue, newValue) -> {
        // Do whatever you want if the its value changed.
        // You can also use its old or new value.
    });