JavaFX的WebView中通过JavaScript回调Java的程序
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 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;
}
}
Online Help
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() {
@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。