解决webview首次加载的html页面无法使用js调用java程序问题。
根据官网给出的例子，自己写了个总是调用不成功。以下是官网例子代码：
http://docs.oracle.com/javase/8/javafx/embedded-browser-tutorial/js-javafx.htm
import javafx.application.Application;import javafx.application.Platform;import javafx.beans.value.ObservableValue;import javafx.concurrent.Worker.State;import javafx.event.ActionEvent;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.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.WebEngine;import javafx.scene.web.WebView;import javafx.stage.Stage;import netscape.javascript.JSObject; public class WebViewSample extends Application { private Scene scene; @Override public void start(Stage stage) { // create scene stage.setTitle("Web View Sample"); scene = new Scene(new Browser(stage), 900, 600, 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 final HBox toolBar; final private static String[] imageFiles = new String[]{ "product.png", "blog.png", "documentation.png", "partners.png", "help.png" }; final private static String[] captions = new String[]{ "Products", "Blogs", "Documentation", "Partners", "Help" }; final private static String[] urls = new String[]{ "http://www.oracle.com/products/index.html", "http://blogs.oracle.com/", "http://docs.oracle.com/javase/index.html", "http://www.oracle.com/partners/index.html", WebViewSample.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 toggleHelpTopics = new Button("Toggle Help Topics"); private boolean needDocumentationButton = false; public Browser(final Stage stage) { //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 addButton = (hpl.getText().equals("Help")); // process event hpl.setOnAction((ActionEvent e) -> { needDocumentationButton = addButton; webEngine.load(url); }); } // create the toolbar toolBar = new HBox(); toolBar.setAlignment(Pos.CENTER); toolBar.getStyleClass().add("browser-toolbar"); toolBar.getChildren().addAll(hpls); toolBar.getChildren().add(createSpacer()); //set action for the button toggleHelpTopics.setOnAction((ActionEvent t) -> { webEngine.executeScript("toggle_visibility('help_topics')"); }); // process page loading webEngine.getLoadWorker().stateProperty().addListener( (ObservableValue<? extends State> ov, State oldState, State newState) -> { toolBar.getChildren().remove(toggleHelpTopics); if (newState == State.SUCCEEDED) { JSObject win = (JSObject) webEngine.executeScript("window"); win.setMember("app", new JavaApp()); if (needDocumentationButton) { toolBar.getChildren().add(toggleHelpTopics); } } }); // 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 900; } @Override protected double computePrefHeight(double width) { return 600; }}<html lang="en"> <head> <!-- Visibility toggle script --> <script type="text/javascript"> <!-- function toggle_visibility(id) { var e = document.getElementById(id); if (e.style.display == 'block') e.style.display = 'none'; else e.style.display = 'block'; }//--> </script> </head> <body> <h1>Online Help</h1> <p class="boxtitle"><a href="#" onclick="toggle_visibility('help_topics');" class="boxtitle">[+] Show/Hide Help Topics</a></p> <ul id="help_topics" style='display:none;'> <li>Products - Extensive overview of Oracle hardware and software products, and summary Oracle consulting, support, and educational services. </li> <li>Blogs - Oracle blogging community (use the Hide All and Show All buttons to collapse and expand the list of topics).</li> <li>Documentation - Landing page to start learning Java. The page contains links to the Java tutorials, developer guides, and API documentation.</li> <li>Partners - Oracle partner solutions and programs. Popular resources and membership opportunities.</li> </ul> <p><a href="about:blank" onclick="openAppUtil.exit()">Exit the Application</a></p> </body></html>弄了几个小时，最后怀疑是不是javafx版本问题，我的版本和官网给的例子不一致导致的。
于是我就把官网的例子代码拷贝下来，直接使用它的例子，居然成功了。看来是程序哪里出问题了。
接下来就是不停的对照代码，希望能发现问题所在。又是2个多小时过去了，终于找到问题所在了，原来要右键点击重新加载一次页面，js才能调用java程序。
好奇怪的现象！！！官网例子不用重新加载是因为进入help.html页面是通过点击工具栏上的help按钮，浏览器才加载进去的，浏览器首次加载的是Oracle首页。
如果把官网例子
webEngine.load("http://www.oracle.com/products/index.html");
改为
webEngine.load(WebViewSample.class.getResource("help.html").toExternalForm());
那么一样也会出现点击超链接后不会退出程序，而是会进入一个空白页面，然后需要鼠标右击选择退回，再次点击超链接才能退出程序。
也就是说help.html页面要第二次加载js中才能调用java程序。
下面是我写的例子的解决方案。
package application.view;import application.Main;import application.util.ConfigUtil;import application.util.OpenAppUtil;import javafx.beans.value.ChangeListener;import javafx.beans.value.ObservableValue;import javafx.concurrent.Worker;import javafx.concurrent.Worker.State;import javafx.fxml.FXML;import javafx.scene.web.WebEngine;import javafx.scene.web.WebView;import netscape.javascript.JSObject;/** * 根面板控制器 * @author pelin */public class RootLayoutController { @FXML WebView browser; WebEngine webEngine; /** * 初始化，类似与构造函数. fxml加载完成后自动调用该方法 */ @FXML private void initialize() { webEngine = browser.getEngine(); OpenAppUtil openAppUtil = new OpenAppUtil(); webEngine.getLoadWorker().stateProperty().addListener( new ChangeListener<State>() { @Override public void changed(ObservableValue ov, State oldState, State newState) { if (newState == Worker.State.SUCCEEDED) {// stage.setTitle(webEngine.getLocation());// System.out.println(newState); JSObject win = (JSObject) webEngine.executeScript("window"); win.setMember("openAppUtil", openAppUtil); } else if (newState == Worker.State.FAILED){// System.out.println(newState);// webEngine.load(HtmlPath.class.getResource("home.html").toExternalForm()); } else{// System.out.println(newState); } } });// webEngine.load(ConfigUtil.getValue("homePage")); webEngine.load(Main.class.getResource("view/test.html").toExternalForm());// webEngine.load("http://10.100.1.240:8089/test.html"); } }主要修改的地方是：
win.setMember("openAppUtil", new OpenAppUtil());
改为
win.setMember("openAppUtil", openAppUtil);
并且在webEngine.getLoadWorker().stateProperty().addListener之前创建openAppUtil对象。即：OpenAppUtil openAppUtil = new OpenAppUtil();
这样webview在首次加载html后就可以调用java程序了。
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