（翻译）第二十三回 JavaFX2.0 超链接Hyperlink

原文地址http://download.oracle.com/javafx/2.0/ui_controls/hyperlink.htm

 

 

 

Hyperlink 类呈现的是Labeled 控件的另一种形式，主要用来格式化超链接文本。Figure 17-1 显示了默认超链接的三个实现状态。

 

Figure 17-1 Three States of a Hyperlink Control

Description of "Figure 17-1 Three States of a Hyperlink Control"

 

创建Hyperlink

这些代码将产生上面的效果 Example 17-1 .

Example 17-1 Typical Hyperlink

Hyperlink link = new Hyperlink();
link.setText("http://example.com");
link.setOnAction(new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent e) {
        System.out.println("This link is clicked");
    }
});

setText实例方法定义了超链接的文本。由于 Hyperlink 类继承了Labeled 类，所以可以为超链接指定特定的字体和内容。setOnAction 方法定义了任何时候点击超链接的行为，和Button控件很像。在 Example 17-1 中，这种行为只是用来打印一个字符串。实际上，它可以实现更多更复杂的认为。

连接到本地内容

 Figure 17-2 中的应用显示了本地的图片。

 

Figure 17-2 Viewing Images

Description of "Figure 17-2 Viewing Images"

 

看下它的代码 Example 17-2 .

Example 17-2 Using Hyperlinks to VIew Images

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
 
public class Main extends Application {
 
    final static String[] imageFiles = new String[]{
        "product.png",
        "education.png",
        "partners.png",
        "support.png"
    };
    final static String[] captions = new String[]{
        "Products",
        "Education",
        "Partners",
        "Support"
    };
    final ImageView selectedImage = new ImageView();
    final ScrollPane list = new ScrollPane();
    final Hyperlink[] hpls = new Hyperlink[captions.length];
    final Image[] images = new Image[imageFiles.length];
 
    public static void main(String[] args) {
        Application.launch(args);
    }
 
    @Override
    public void start(Stage stage) {
        Scene scene = new Scene(new Group());
        stage.setTitle("Hyperlink Sample");
        stage.setWidth(300);
        stage.setHeight(200);
 
        selectedImage.setLayoutX(100);
        selectedImage.setLayoutY(10);
 
        for (int i = 0; i < captions.length; i++) {
            final Hyperlink hpl = hpls[i] = new Hyperlink(captions[i]);
            final Image image = images[i] = new Image(
                getClass().getResourceAsStream(imageFiles[i])
            );
            hpl.setOnAction(new EventHandler<ActionEvent>() {
                @Override
                public void handle(ActionEvent e) {
                    selectedImage.setImage(image);
                }
            });
        }
 
        final Button button = new Button("Refresh links");
        button.setOnAction(new EventHandler<ActionEvent>() {
                @Override
                public void handle(ActionEvent e) {
                    for (int i = 0; i < captions.length; i++) {
                        hpls[i].setVisited(false);
                        selectedImage.setImage(null);
                    }
                }
            });
 
        VBox vbox = new VBox();
        vbox.getChildren().addAll(hpls);
        vbox.getChildren().add(button);
        vbox.setSpacing(5);
 
        ((Group) scene.getRoot()).getChildren().addAll(vbox, selectedImage);
        stage.setScene(scene);
        stage.show();
    }
}

该应用在for循环中创建了四个 Hyperlink 对象。点击特点的超链接会调用setOnAction 方法产生不同的行为。这样，images数组中相应的图片就设置给 selectedImage 变量。

当点击一个超链接时，它就成为了访问过的（visited）。可以使用Hyperlink 类的setVisited 方法刷新链接。见Example 17-3 中的代码。

 

Example 17-3 Refreshing the HyperlInks

final Button button = new Button("Refresh links");
button.setOnAction(new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent e) {
       for (int i = 0; i < captions.length; i++) {
           hpls[i].setVisited(false);
           selectedImage.setImage(null);
       }
    }
});

 

点击Refresh Links按钮就会就把超链接都充值为未访问状态。见Figure 17-3 .

Figure 17-3 Unvisited Hyperlinks

Description of "Figure 17-3 Unvisited Hyperlinks"

由于Hyperlink类继承了 Labeled 类，所以除了文本还可以为其指定图片。下一部分的应用就使用了文本和图片链接并加载远程HTML页面。

链接到远程内容

可以在JavaFX应用中显示HTML内容，方法是在场景内绑定WebView 浏览器。WebView 组件提供了网页的基本浏览功能。除此之外，还支持用户交互，如导航和执行JavaScript命令。

研究Example 17-4 中的代码，它创建了带有文本和图像的超链接。点击超链接后，相应的值就作为URL传递给绑定的浏览器。

 

Example 17-4 Loading Remote Web Pages

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;
import javafx.stage.Stage;
 
public class Main extends Application {
 
    final static String[] imageFiles = new String[]{
        "product.png",
        "education.png",
        "partners.png",
        "support.png"
    };
    final static String[] captions = new String[]{
        "Products",
        "Education",
        "Partners",
        "Support"
    };
 
    final static String[] urls = new String[]{
        "http://www.oracle.com/us/products/index.html",
        "http://education.oracle.com/",
        "http://www.oracle.com/partners/index.html",
        "http://www.oracle.com/us/support/index.html"
    };
    
    final ImageView selectedImage = new ImageView();
    final Hyperlink[] hpls = new Hyperlink[captions.length];
    final Image[] images = new Image[imageFiles.length];   
 
    public static void main(String[] args){
        launch(args);
    }
 
    @Override
    public void start(Stage stage) {
        VBox vbox = new VBox();
        Scene scene = new Scene(vbox);
        stage.setTitle("Hyperlink Sample");
        stage.setWidth(570);
        stage.setHeight(550);
 
        selectedImage.setLayoutX(100);
        selectedImage.setLayoutY(10);
        
        final WebView browser = new WebView();
        final WebEngine webEngine = browser.getEngine();
 
        for (int i = 0; i < captions.length; i++) {
            final Hyperlink hpl = hpls[i] = new Hyperlink(captions[i]);
 
            final Image image = images[i] =
                    new Image(getClass().getResourceAsStream(imageFiles[i]));
            hpl.setGraphic(new ImageView (image));
            hpl.setFont(Font.font("Arial", 14));
            final String url = urls[i];
 
            hpl.setOnAction(new EventHandler<ActionEvent>() {
                @Override
                public void handle(ActionEvent e) {
                    webEngine.load(url);
                }
            });
        }
              
        HBox hbox = new HBox();
        hbox.getChildren().addAll(hpls);
 
        vbox.getChildren().addAll(hbox, browser);
        VBox.setVgrow(browser, Priority.ALWAYS);
        
        stage.setScene(scene);
        stage.show();
    }
}

 

超链接也在for循环中创建，类似于 Example 17-2 。为超链接设置的行为从urls数组到 WebEngine 对象传递了相应的URL。

编译运行效果如Figure 17-4 .

Figure 17-4 Loading Pages from the Oracle Corporate Site

Description of "Figure 17-4 Loading Pages from the Oracle Corporate Site"