java - webview 无法像网络浏览器一样运行

Question

我正在尝试在 javafx webview 的帮助下创建一个网络浏览器。 我正在使用以下代码来创建网络浏览器。运行程序时出现错误异常

    package webviewbrowser;

    import com.sun.javaws.Main;
    import javafx.application.Application;
    import javafx.application.Platform;
    import javafx.beans.value.ChangeListener;
    import javafx.beans.value.ObservableValue;
    import javafx.collections.ListChangeListener;
    import javafx.collections.ListChangeListener.Change;
    import javafx.concurrent.Worker.State;
    import javafx.event.ActionEvent;
    import javafx.event.Event;
    import javafx.event.EventHandler;
    import javafx.geometry.HPos;
    import javafx.geometry.Pos;
    import javafx.geometry.VPos;
    import javafx.scene.Node;
    import javafx.scene.Scene;
    import javafx.scene.control.Button;
    import javafx.scene.control.ComboBox;
    import javafx.scene.control.Hyperlink;
    import javafx.scene.image.Image;

    import javafx.scene.image.ImageView;
    import javafx.scene.layout.HBox;
    import javafx.scene.layout.Priority;
    import javafx.scene.layout.Region;
    import javafx.scene.paint.Color;
    import javafx.scene.web.PopupFeatures;
    import javafx.scene.web.WebEngine;
    import javafx.scene.web.WebHistory;
    import javafx.scene.web.WebHistory.Entry;
    import javafx.scene.web.WebView;
    import javafx.stage.Stage;
    import javafx.util.Callback;
    import netscape.javascript.JSObject;

     public class WebViewBrowser extends Application {

      private Scene scene;

      @Override
       public void start(Stage stage) {
        // create scene
        stage.setTitle("Web View");
        scene = new Scene(new Browser(), 750, 500, Color.web("#666970"));
        stage.setScene(scene);
        // apply CSS style
        scene.getStylesheets().add("webviewsample/BrowserToolbar.css");
        // show stage
        stage.show();
       }

      public static void main(String[] args) {
         launch(args);
      }
    }

    class Browser extends Region {

     private HBox toolBar;
      private static String[] imageFiles = new String[]{
        "product.png",
        "blog.png",
        "forum.png",
        "partners.png",
        "help.png"
       };
      private static String[] captions = new String[]{
        "Products",
        "Blogs",
        "Forums",
        "Partners",
        "Help"
      };
     private static String[] urls = new String[]{
        "http://www.oracle.com/products/index.html",
        "http://blogs.oracle.com/",
        "http://forums.oracle.com/forums/",
        "http://www.oracle.com/partners/index.html",
        Main.class.getResource("help.html").toExternalForm()
      };
    final ImageView selectedImage = new ImageView();
    final Hyperlink[] hpls = new Hyperlink[captions.length];
    final Image[] images = new Image[imageFiles.length];
    final WebView browser = new WebView();
    final WebEngine webEngine = browser.getEngine();
    final Button hideAll = new Button("Hide All");
    final Button showAll = new Button("ShowAll");
    final WebView smallView = new WebView();
    final ComboBox comboBox = new ComboBox();
    private boolean needForumButtons = false;

         public Browser() {
         //apply the styles
         getStyleClass().add("browser");

        for (int i = 0; i < captions.length; i++) {
            // create hyperlinks
            Hyperlink hpl = hpls[i] = new Hyperlink(captions[i]);
            Image image = images[i] =
                    new Image(getClass().getResourceAsStream(imageFiles[i]));
            hpl.setGraphic(new ImageView(image));
            final String url = urls[i];
            final boolean addButtons = (hpl.getText().equals("Forums"));

            // process event 
            hpl.setOnAction(new EventHandler<ActionEvent>() {
                @Override
                public void handle(ActionEvent e) {
                    needForumButtons = addButtons;
                    webEngine.load(url);
                }
            });
        }

        comboBox.setPrefWidth(60);

        // create the toolbar
        toolBar = new HBox();
        toolBar.setAlignment(Pos.CENTER);
        toolBar.getStyleClass().add("browser-toolbar");
        toolBar.getChildren().add(comboBox);
        toolBar.getChildren().addAll(hpls);
        toolBar.getChildren().add(createSpacer());

        //set actions for the buttons
        hideAll.setOnAction(new EventHandler() {
            @Override
            public void handle(Event t) {
                webEngine.executeScript("hideAll()");
            }
        });

        showAll.setOnAction(new EventHandler() {
            @Override
            public void handle(Event t) {
                webEngine.executeScript("showAll()");
            }
        });

        smallView.setPrefSize(120, 80);

        //handle popup windows
        webEngine.setCreatePopupHandler(
            new Callback<PopupFeatures, WebEngine>() {
                @Override public WebEngine call(PopupFeatures config) {
                    smallView.setFontScale(0.8);
                    if (!toolBar.getChildren().contains(smallView)) {
                        toolBar.getChildren().add(smallView);
                    }
                    return smallView.getEngine();
                }
             }
        );

        //process history
        final WebHistory history = webEngine.getHistory();
        history.getEntries().addListener(new 
            ListChangeListener<WebHistory.Entry>(){
                @Override
                public void onChanged(Change<? extends Entry> c) {
                    c.next();
                    for (Entry e : c.getRemoved()) {
                        comboBox.getItems().remove(e.getUrl());
                    }
                    for (Entry e : c.getAddedSubList()) {
                        comboBox.getItems().add(e.getUrl());
                    }
                }
        });

        //set the behavior for the history combobox               
        comboBox.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent ev) {
                int offset =
                        comboBox.getSelectionModel().getSelectedIndex()
                        - history.getCurrentIndex();
                history.go(offset);
            }
        });



        // process page loading
        webEngine.getLoadWorker().stateProperty().addListener(
            new ChangeListener<State>() {
                @Override
                public void changed(ObservableValue<? extends State> ov,
                    State oldState, State newState) {
                    toolBar.getChildren().removeAll(showAll, hideAll);    
                    if (newState == State.SUCCEEDED) {
                            JSObject win = 
                                (JSObject) webEngine.executeScript("window");
                            win.setMember("app", new JavaApp());
                            if (needForumButtons) {
                                toolBar.getChildren().addAll(showAll, hideAll);
                            }
                        }
                    }
                }
        );

        // load the home page        
        webEngine.load("http://www.oracle.com/products/index.html");

        //add components
        getChildren().add(toolBar);
        getChildren().add(browser);
    }

    // JavaScript interface object
    public class JavaApp {

        public void exit() {
            Platform.exit();
        }
    }

    private Node createSpacer() {
        Region spacer = new Region();
        HBox.setHgrow(spacer, Priority.ALWAYS);
        return spacer;
    }

    @Override
    protected void layoutChildren() {
        double w = getWidth();
        double h = getHeight();
        double tbHeight = toolBar.prefHeight(w);
        layoutInArea(browser,0,0,w,h-tbHeight,0,HPos.CENTER,VPos.CENTER);
        layoutInArea(toolBar,0,h-tbHeight,w,tbHeight,0,HPos.CENTER,VPos.CENTER);
    }

    @Override
    protected double computePrefWidth(double height) {
        return 750;
    }

    @Override
    protected double computePrefHeight(double width) {
        return 600;
    }
}

Answer 1

为我工作。

该代码只是引用了一些本地 html、css 和图像资源，这些资源未包含在您的问题中。因为它们不存在，如果您只是复制、粘贴并运行，那么您会由于缺少资源文件而得到 NullPointerExceptions。

<小时/>

对于任何想知道问题中的大部分代码来自哪里的人来说，它是 Oracle 的一部分 Adding HTML Content to JavaFX Applications 。可以从教程链接以及 NetBeans 项目下载与代码配合使用并允许其无需修改即可运行的其他资源(html、css 等)，您只需加载即可运行该程序。

<小时/>

我注释掉了对外部资源的引用，以便程序可以独立运行。它的图像等样式并不都很好。但它似乎对我来说工作得很好。

import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.ListChangeListener;
import javafx.concurrent.Worker.State;
import javafx.event.ActionEvent;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.geometry.HPos;
import javafx.geometry.Pos;
import javafx.geometry.VPos;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Hyperlink;
import javafx.scene.image.Image;

import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.Region;
import javafx.scene.paint.Color;
import javafx.scene.web.PopupFeatures;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebHistory;
import javafx.scene.web.WebHistory.Entry;
import javafx.scene.web.WebView;
import javafx.stage.Stage;
import javafx.util.Callback;
import netscape.javascript.JSObject;

public class WebViewBrowser extends Application {

  private Scene scene;

  @Override
  public void start(Stage stage) {
    // create scene
    stage.setTitle("Web View");
    scene = new Scene(new Browser(), 750, 500, Color.web("#666970"));
    stage.setScene(scene);
    // apply CSS style
//    scene.getStylesheets().add("webviewsample/BrowserToolbar.css");
    // show stage
    stage.show();
  }

  public static void main(String[] args) {
    launch(args);
  }
}

class Browser extends Region {

  private HBox toolBar;
  private static String[] imageFiles = new String[]{
      "product.png",
      "blog.png",
      "forum.png",
      "partners.png",
      "help.png"
  };
  private static String[] captions = new String[]{
      "Products",
      "Blogs",
      "Forums",
      "Partners"
//      "Help"
  };
  private static String[] urls = new String[]{
      "http://www.oracle.com/products/index.html",
      "http://blogs.oracle.com/",
      "http://forums.oracle.com/forums/",
      "http://www.oracle.com/partners/index.html"
//      Main.class.getResource("help.html").toExternalForm()
  };
  final ImageView selectedImage = new ImageView();
  final Hyperlink[] hpls = new Hyperlink[captions.length];
  final Image[] images = new Image[imageFiles.length];
  final WebView browser = new WebView();
  final WebEngine webEngine = browser.getEngine();
  final Button hideAll = new Button("Hide All");
  final Button showAll = new Button("ShowAll");
  final WebView smallView = new WebView();
  final ComboBox comboBox = new ComboBox();
  private boolean needForumButtons = false;

  public Browser() {
    //apply the styles
    getStyleClass().add("browser");

    for (int i = 0; i < captions.length; i++) {
      // create hyperlinks
      Hyperlink hpl = hpls[i] = new Hyperlink(captions[i]);
//      Image image = images[i] =
//          new Image(getClass().getResourceAsStream(imageFiles[i]));
//      hpl.setGraphic(new ImageView(image));
      final String url = urls[i];
      final boolean addButtons = (hpl.getText().equals("Forums"));

      // process event
      hpl.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent e) {
          needForumButtons = addButtons;
          webEngine.load(url);
        }
      });
    }

    comboBox.setPrefWidth(60);

    // create the toolbar
    toolBar = new HBox();
    toolBar.setAlignment(Pos.CENTER);
    toolBar.getStyleClass().add("browser-toolbar");
    toolBar.getChildren().add(comboBox);
    toolBar.getChildren().addAll(hpls);
    toolBar.getChildren().add(createSpacer());

    //set actions for the buttons
    hideAll.setOnAction(new EventHandler() {
      @Override
      public void handle(Event t) {
        webEngine.executeScript("hideAll()");
      }
    });

    showAll.setOnAction(new EventHandler() {
      @Override
      public void handle(Event t) {
        webEngine.executeScript("showAll()");
      }
    });

    smallView.setPrefSize(120, 80);

    //handle popup windows
    webEngine.setCreatePopupHandler(
        new Callback<PopupFeatures, WebEngine>() {
          @Override public WebEngine call(PopupFeatures config) {
            smallView.setFontScale(0.8);
            if (!toolBar.getChildren().contains(smallView)) {
              toolBar.getChildren().add(smallView);
            }
            return smallView.getEngine();
          }
        }
    );

    //process history
    final WebHistory history = webEngine.getHistory();
    history.getEntries().addListener(new
                                         ListChangeListener<WebHistory.Entry>(){
                                           @Override
                                           public void onChanged(Change<? extends Entry> c) {
                                             c.next();
                                             for (Entry e : c.getRemoved()) {
                                               comboBox.getItems().remove(e.getUrl());
                                             }
                                             for (Entry e : c.getAddedSubList()) {
                                               comboBox.getItems().add(e.getUrl());
                                             }
                                           }
                                         });

    //set the behavior for the history combobox
    comboBox.setOnAction(new EventHandler<ActionEvent>() {
      @Override
      public void handle(ActionEvent ev) {
        int offset =
            comboBox.getSelectionModel().getSelectedIndex()
                - history.getCurrentIndex();
        history.go(offset);
      }
    });



    // process page loading
    webEngine.getLoadWorker().stateProperty().addListener(
        new ChangeListener<State>() {
          @Override
          public void changed(ObservableValue<? extends State> ov,
                              State oldState, State newState) {
            toolBar.getChildren().removeAll(showAll, hideAll);
            if (newState == State.SUCCEEDED) {
              JSObject win =
                  (JSObject) webEngine.executeScript("window");
              win.setMember("app", new JavaApp());
              if (needForumButtons) {
                toolBar.getChildren().addAll(showAll, hideAll);
              }
            }
          }
        }
    );

    // load the home page
    webEngine.load("http://www.oracle.com/products/index.html");

    //add components
    getChildren().add(toolBar);
    getChildren().add(browser);
  }

  // JavaScript interface object
  public class JavaApp {

    public void exit() {
      Platform.exit();
    }
  }

  private Node createSpacer() {
    Region spacer = new Region();
    HBox.setHgrow(spacer, Priority.ALWAYS);
    return spacer;
  }

  @Override
  protected void layoutChildren() {
    double w = getWidth();
    double h = getHeight();
    double tbHeight = toolBar.prefHeight(w);
    layoutInArea(browser,0,0,w,h-tbHeight,0,HPos.CENTER,VPos.CENTER);
    layoutInArea(toolBar,0,h-tbHeight,w,tbHeight,0,HPos.CENTER,VPos.CENTER);
  }

  @Override
  protected double computePrefWidth(double height) {
    return 750;
  }

  @Override
  protected double computePrefHeight(double width) {
    return 600;
  }
}

<小时/>

很久以前我创建了一个 WebView Web Browser 。您可以看看它，为您的网络浏览器获得一些灵感。我的浏览器中的代码需要进行一些清理和更改，以利用 WebView 的一些更现代的内置功能，例如 WebView 的内置历史列表，但它是一个非常实用的选项卡式浏览器，也许您仍然会找到它有用。