（翻譯）第二十三回 JavaFX2.0 超鏈接Hyperlink

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

 

 

 

Hyperlink 類呈現的是Labeled 控件的另一種形式，主要用來格式化超鏈接文本。Figure 17-1 顯示了默認超鏈接的三個實現狀態。

 

Figure 17-1 Three States of a Hyperlink Control

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

 

創建Hyperlink

這些代碼將產生上面的效果 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實例方法定義了超鏈接的文本。由於 Hyperlink 類繼承了Labeled 類，所以可以爲超鏈接指定特定的字體和內容。setOnAction 方法定義了任何時候點擊超鏈接的行爲，和Button控件很像。在 Example 17-1 中，這種行爲只是用來打印一個字符串。實際上，它可以實現更多更復雜的認爲。

連接到本地內容

 Figure 17-2 中的應用顯示了本地的圖片。

 

Figure 17-2 Viewing Images

Description of "Figure 17-2 Viewing Images"

 

看下它的代碼 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();
    }
}

該應用在for循環中創建了四個 Hyperlink 對象。點擊特點的超鏈接會調用setOnAction 方法產生不同的行爲。這樣，images數組中相應的圖片就設置給 selectedImage 變量。

當點擊一個超鏈接時，它就成爲了訪問過的（visited）。可以使用Hyperlink 類的setVisited 方法刷新鏈接。見Example 17-3 中的代碼。

 

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);
       }
    }
});

 

點擊Refresh Links按鈕就會就把超鏈接都充值爲未訪問狀態。見Figure 17-3 .

Figure 17-3 Unvisited Hyperlinks

Description of "Figure 17-3 Unvisited Hyperlinks"

由於Hyperlink類繼承了 Labeled 類，所以除了文本還可以爲其指定圖片。下一部分的應用就使用了文本和圖片鏈接並加載遠程HTML頁面。

鏈接到遠程內容

可以在JavaFX應用中顯示HTML內容，方法是在場景內綁定WebView 瀏覽器。WebView 組件提供了網頁的基本瀏覽功能。除此之外，還支持用戶交互，如導航和執行JavaScript命令。

研究Example 17-4 中的代碼，它創建了帶有文本和圖像的超鏈接。點擊超鏈接後，相應的值就作爲URL傳遞給綁定的瀏覽器。

 

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();
    }
}

 

超鏈接也在for循環中創建，類似於 Example 17-2 。爲超鏈接設置的行爲從urls數組到 WebEngine 對象傳遞了相應的URL。

編譯運行效果如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"