Java语言程序设计-基础篇（十三）事件驱动与动画

1.要对事件源进行注册事件，然后处理事件，才能对事件做出相应的反应。下面程序写出来通过按钮使圆形扩大或者缩小。

package practice;
import javafx.application.*;
import javafx.scene.*;
import javafx.stage.*;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.layout.HBox;

public class demo extends Application{
  public void start(Stage primaryStage){   
    Pane pane = new Pane();
    Scene scene = new Scene(pane,300,300);
    HBox hb = new HBox();
    Circle circle = new Circle(100);
    circle.centerXProperty().bind(scene.widthProperty().divide(2));
    circle.centerYProperty().bind(scene.heightProperty().divide(2));
    circle.setFill(Color.WHITE);
    circle.setStroke(Color.BLUE);
    Button btl = new Button("Enlarge");
    Button bts = new Button("Shrink");
    hb.getChildren().add(btl);
    hb.getChildren().add(bts);
    pane.getChildren().addAll(circle,hb);
    
    btl.setOnAction(e->circle.setRadius(circle.getRadius()+10));
    bts.setOnAction(e->circle.setRadius(circle.getRadius()-10));
    
    primaryStage.setTitle("controlcircle");
    primaryStage.setScene(scene);
    primaryStage.show();
  }
  
}

其中是用来注册事件和处理事件的，这里用到了lamabda的表达方法，lamabda的表达方式使对匿名内部类的省略，匿名内部类是对内部类的省略。这样可以使语法更加清晰。

btl.setOnAction(e->circle.setRadius(circle.getRadius()+10));

2.lamabda的应用，实现了一个简单的加法程序。

package practice;
import javafx.application.*;
import javafx.geometry.Insets;
import javafx.scene.*;
import javafx.stage.*;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.text.Text;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;

public class demo extends Application{

  public void start(Stage primaryStage){   
    GridPane pane = new GridPane();
    Scene scene = new Scene(pane,300,300);
    pane.add(new Text("number1"), 0, 0);
    pane.add(new Text("number2"), 0, 1);
    pane.add(new Text("resulut"), 0, 2);
    pane.hgapProperty().bind(scene.widthProperty().divide(8));
    pane.vgapProperty().bind(scene.heightProperty().divide(8));
    
    TextField number1 = new TextField("0");
    TextField number2 = new TextField("0");
    TextField result = new TextField("0");
    result.setEditable(false);
    pane.add(number1, 1, 0);
    pane.add(number2, 1, 1);
    pane.add(result, 1, 2);

    Button bt = new Button("calculate!");
    pane.add(bt, 1, 3);
    

    bt.setOnAction(e->{   
       double value1 = Double.parseDouble(number1.getText());
       double value2 = Double.parseDouble(number1.getText());
       Double value = value1+value2;
       String re = value.toString();
       System.out.println(value1+value2);
       result.setText(re);
       }
    );
    
    pane.setPadding(new Insets(20,20,20,20));
    
    
    primaryStage.setTitle("calculate");
    primaryStage.setScene(scene);
    primaryStage.show();
  }
}
 

其中

  bt.setOnAction(e->{   
       double value1 = Double.parseDouble(number1.getText());
       double value2 = Double.parseDouble(number1.getText());
       Double value = value1+value2;
       String re = value.toString();
       System.out.println(value1+value2);
       result.setText(re);
       }
    );

是lamabda的完整应用。另外以下实现了属性的绑定。

 pane.hgapProperty().bind(scene.widthProperty().divide(8));

3.鼠标响应，该程序实现了一个鼠标拖动文本框的程序。

package practice;
import javafx.application.*;
import javafx.geometry.Insets;
import javafx.scene.*;
import javafx.stage.*;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.text.Text;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;

public class demo extends Application{

  public void start(Stage primaryStage){   
    Pane pane = new Pane();
    Scene scene = new Scene(pane,300,300);
    Text text = new Text(50,50,"program is fun");
    pane.getChildren().add(text);
    text.setOnMouseDragged(e->{
       text.setX(e.getX());
       text.setY(e.getY());
    });
    
    
    primaryStage.setTitle("calculate");
    primaryStage.setScene(scene);
    primaryStage.show();
  }
}
 

其中

    text.setOnMouseDragged(e->{
       text.setX(e.getX());
       text.setY(e.getY());
    });

是对鼠标拖拽事件的注册与实现。

4.事件注册表格一览