javafx Application Logic浅析

1.Scene Graph体系结构浅析

javafx以tree的形式组织nodes,每一个node就是一个control,即UI组件。

node分为leaf node与branch node， root node。

scene体系中最关键的类：

Scene:代表包含所有UI组件的顶级容器

Node：是一个抽象类，代表UI组件的基类

Parent:是一个抽象类，代表branch node的基类。

2.Properties与Binding

秒懂javafx中property的规范：

package propertydemo;

import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
 
class Bill {
 
    // Define a variable to store the property
    private DoubleProperty amountDue = new SimpleDoubleProperty();
 
    // Define a getter for the property‘s value
    public final double getAmountDue(){return amountDue.get();}
 
    // Define a setter for the property‘s value
    public final void setAmountDue(double value){amountDue.set(value);}
 
     // Define a getter for the property itself
    public DoubleProperty amountDueProperty() {return amountDue;}
 
}

理解监听机制：

 Bill electricBill = new Bill();
 
       electricBill.amountDueProperty().addListener(new ChangeListener(){
        @Override public void changed(ObservableValue o,Object oldVal, 
                 Object newVal){
             System.out.println("Electric bill has changed!");
        }
      });
     
      electricBill.setAmountDue(100.00);

Bindings与property的关系

IntegerProperty num1 = new SimpleIntegerProperty(1);
        IntegerProperty num2 = new SimpleIntegerProperty(2);
        NumberBinding sum = num1.add(num2);
       //也可以是这种方式：NumberBinding sum = Bindings.add(num1,num2);

        System.out.println(sum.getValue());
        num1.set(2);
        System.out.println(sum.getValue());

   NumberBinding total =
          Bindings.add(bill1.amountDueProperty().add(bill2.amountDueProperty()),
              bill3.amountDueProperty());
        total.addListener(new InvalidationListener() {
 
        @Override public void invalidated(Observable o) {
                System.out.println("The binding is now invalid.");
            }
        });

        // First call makes the binding invalid
        bill1.setAmountDue(200.00);

        // The binding is now invalid
        bill2.setAmountDue(100.00);
        bill3.setAmountDue(75.00);

        // Make the binding valid...
        System.out.println(total.getValue());

 final DoubleProperty a = new SimpleDoubleProperty(1);
        final DoubleProperty b = new SimpleDoubleProperty(2);
        final DoubleProperty c = new SimpleDoubleProperty(3);
        final DoubleProperty d = new SimpleDoubleProperty(4);
 
        DoubleBinding db = new DoubleBinding() {
 
            {
                super.bind(a, b, c, d);
            }
 
            @Override
            protected double computeValue() {
                return (a.get() * b.get()) + (c.get() * d.get());
            }
        };
 
        System.out.println(db.get());
        b.set(3);

javafx Collections是基于java基础类库中的集合框架的，只不过是结合了javafx中的Observable,使之成为可以观察变化的集合。便于javafx的模型数据维护。

javafx.collections包中的主要类：

接口：
ObservableList,             ObservableMap ：被监听者集合

ListChangeListener  MapChangeListener  监听器集合

类：

FXCollections:它是一个基于java.util.Collections的一比一复制品。只不过是做了一层javafx的本地化。但是它是最重要的类了，一切ObservableList/Map均由它的工厂方法产生。

ListChangeListener.Change              MapChangeListener.Change:包含者列表或map中的所有变化。可以进行迭代操作。

Change类包含的变化种类有：排序变化，添加删除变化，更新变化。并有对应的判断方法。

  // Use Java Collections to create the List.
        List<String> list = new ArrayList<String>();
 
        // Now add observability by wrapping it with ObservableList.
    ObservableList<String> observableList = FXCollections.observableList(list);
        observableList.addListener(new ListChangeListener() {
 
            @Override
            public void onChanged(ListChangeListener.Change change) {
                System.out.println("Detected a change! ");
            }
        });
 
        // Changes to the observableList WILL be reported.
        // This line will print out "Detected a change!"
        observableList.add("item one");

// This code will work with any of the previous ObservableList examples
observableList.addListener(new ListChangeListener() {
 
@Override
public void onChanged(ListChangeListener.Change change) {
    System.out.println("Detected a change! ");
    while (change.next()) {
        System.out.println("Was added? " + change.wasAdded());
        System.out.println("Was removed? " + change.wasRemoved());
        System.out.println("Was replaced? " + change.wasReplaced());
        System.out.println("Was permutated? " + change.wasPermutated());
        }
    }
});

 ObservableList theList = ...;

 theList.addListener(new ListChangeListener<Item>() {
     public void onChanged(Change<tem> c) {
         while (c.next()) {
             if (c.wasPermutated()) {
                     for (int i = c.getFrom(); i < c.getTo(); ++i) {
                          //permutate
                     }
                 } else if (c.wasUpdated()) {
                          //update item
                 } else {
                     for (Item remitem : c.getRemoved()) {
                         remitem.remove(Outer.this);
                     }
                     for (Item additem : c.getAddedSubList()) {
                         additem.add(Outer.this);
                     }