如何使用 JSNI 从 GWT Java 运行 JavaScript 函数? [英] How to run JavaScript function from GWT Java with JSNI?

问题描述

无法从手册中理解:如何从 Java 中实际运行 JS 函数?

Can't understand from the manual: how actually to run JS function from Java?

例如，我的 html 页面中有一个函数:

For example, I have a function in my html page:

<script type="text/javascript" language="javascript">
    function foo() {
        alert('Foo!');
    }
</script>

以下模块显示了两个按钮，其中只有第二个有效:

The following module shows two buttons, only second of which works:

public class Test_GoogleWeb_JSNI_01 implements EntryPoint {

public void onModuleLoad() {

    Button fooButton = new Button("Foo!");
    fooButton.addClickHandler(new ClickHandler(){
        public void onClick(ClickEvent event) {
            fooRunner();
        };
    });


    HTML fooButtonNative = new HTML();
    fooButtonNative.setHTML("<input type='button' value='Foo Native' onclick='foo()'>");

    RootPanel rootPanel = RootPanel.get();
    rootPanel.add(fooButton);
    rootPanel.add(fooButtonNative);

}

public static native void fooRunner() /*-{
  foo();
}-*/;
}

手册中说，在嵌套框架内实现的原生函数，解释了这种情况.那么如何运行JS函数呢?

It is said in manual, that native functions implemented within nested frame, which explains the situation. But how to run JS functions then?

更新 1以下作品.

Java:

public static native void fooRunner() /*-{
  $doc.fooRunner();
}-*/;

JS:

<script type="text/javascript" language="javascript">
    document.fooRunner = function foo() {
        alert('Foo!');
    }
</script>

有更好的方法吗?

推荐答案

您自己回答了问题.没有更好的方法，原因很简单:部署 GWT 应用程序有多种方法，在 iframe 中运行只是其中一种选择.所以这就是为什么你必须使用 $wnd 变量来访问外部 JS 函数的原因，所以如果你切换链接器，你的静态代码将正常工作.

You answered your question yourself. There is no better way for a very simple reason: there are multiple ways to deploy GWT app, running in iframe is only one of the options. So that's why you have to use $wnd variable to access external JS function, so in case if you switch the linker , your still code will work just fine.

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