GWT中的本地Javascript方法 [英] Native Javascript method in GWT

问题描述

我在我的一个GWT Java类中有一个本地Javascript方法，但是我无法从本地Javascript代码中调用我的Java方法。我尽可能地遵循这，但我不能让它工作。我编译并在Firefox中运行它，错误控制台说错误：this.lc不是函数。我尝试将所有方法更改为 public ，但这似乎没有什么区别。我做错了什么？

I have a native Javascript method in one of my GWT Java classes, but I'm having trouble calling my Java methods from the native Javascript code. I tried to follow this as closely as I could, but I can't get it to work. I compiled it and ran it in Firefox, and the error console said "Error: this.lc is not a function". I tried changing all the methods to public, but that didn't seem to make a difference. What am I doing wrong?

package com.proprintsgear.design_lab.client;
...
public class ValueBox extends HorizontalPanel {
...
private void fireChange() {
    ...
}

private void increaseValue() {
    ...
}

private native void addNativeMouseWheelListener(String id) /*-{
    function mouseOverHandler(e) {
        $wnd.addEventListener("DOMMouseScroll", scrollWheelMove, false);
    }

    function mouseOutHandler(e) {
        $wnd.removeEventListener("DOMMouseScroll", scrollWheelMove, false);
    }

    function scrollWheelMove(e) {
        if ($wnd.event || $wnd.Event) {
            if (!e) e = $wnd.event;
            if (e.wheelDelta <= 0 || e.detail > 0 ) {
                $wnd.alert("DOWN");
            } else {
                [e-mail]_lab.client.ValueBox::increaseValue()();
            }
            [e-mail]_lab.client.ValueBox::fireChange()();
        }
    }

    var box=$doc.getElementById(id);
    box.addEventListener("mouseout",mouseOutHandler,false);
    box.addEventListener("mouseover",mouseOverHandler,false);
}-*/;

推荐答案

在过去我所做的所有代码，我从未用'this'来标识我的班级，我已经通过了班级。

In all the code I've done in the past, I've never used 'this' to identify my class, I have passed the class in.

例如：改变这个：

private native void addNativeMouseWheelListener(String id) /*-{
    function mouseOverHandler(e) {
        $wnd.addEventListener("DOMMouseScroll", scrollWheelMove, false);
    }

    function mouseOutHandler(e) {
        $wnd.removeEventListener("DOMMouseScroll", scrollWheelMove, false);
    }

    function scrollWheelMove(e) {
        if ($wnd.event || $wnd.Event) {
                if (!e) e = $wnd.event;
                if (e.wheelDelta <= 0 || e.detail > 0 ) {
                        $wnd.alert("DOWN");
                } else {
                        [e-mail]_lab.client.ValueBox::increaseValue()();
                }
                [e-mail]_lab.client.ValueBox::fireChange()();
        }
    }

    var box=$doc.getElementById(id);
    box.addEventListener("mouseout",mouseOutHandler,false);
    box.addEventListener("mouseover",mouseOverHandler,false);
}-*/;

至此：

To this:

private native void addNativeMouseWheelListener(ValueBox instance, String id) /*-{
    function mouseOverHandler(e) {
        $wnd.addEventListener("DOMMouseScroll", scrollWheelMove, false);
    }

    function mouseOutHandler(e) {
        $wnd.removeEventListener("DOMMouseScroll", scrollWheelMove, false);
    }

    function scrollWheelMove(e) {
        if ($wnd.event || $wnd.Event) {
                if (!e) e = $wnd.event;
                if (e.wheelDelta <= 0 || e.detail > 0 ) {
                        $wnd.alert("DOWN");
                } else {
                        [e-mail]_lab.client.ValueBox::increaseValue()();
                }
                [e-mail]_lab.client.ValueBox::fireChange()();
        }
    }

    var box=$doc.getElementById(id);
    box.addEventListener("mouseout",mouseOutHandler,false);
    box.addEventListener("mouseover",mouseOverHandler,false);
}-*/;

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