Android WebView 总是在 loadUrl 上为 javascript getElementById 返回 null

问题描述

我尝试在 android 客户端应用程序的 webview 中填写表单.我知道它应该如何工作，但 getElementById 总是为我返回 null.我在不同的网站上尝试过.

I try to fill out a form inside a webview from the android client app. I know how it should work, but the getElementById always returns null for me. I tried it on different websites.

这是我的 www.google.com 示例.

Here is my example for www.google.com.

MyWebView view = new MyWebView(this);
view.getSettings().setJavaScriptEnabled(true);
view.loadUrl("http://www.google.com");
view.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView v, String url) {
        v.loadUrl(url);
        return true;
    }
    @Override
    public void onPageFinished(WebView v, String url) {
        v.loadUrl("javascript:document.getElementById('mib').value = 'aaa';");
    }
});
setContentView(view);

还有 MyWebView 类(仅供参考).

And the MyWebView class (only for information).

class MyWebView extends WebView {
    Context context;
    public MyWebView(Context context) {
        super(context);
        this.context = context;
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // do some multi touch stuff
        return true;
    }
}

我总是收到错误:

09-01 04:35:26.453: I/chromium(2962): [INFO:CONSOLE(1)] "Uncaught TypeError: Cannot set property 'value' of null", source: https://www.google.de/?gws_rd=ssl (1)

但是元素mib"应该在网站上.使用桌面浏览器(带有移动模拟的 chrome)一切正常.我不知道，这里出了什么问题.

But the element "mib" should be on the site. Using a desktop browser (chrome with mobile simulation) everything is working fine. I have no idea, whats going wrong here.

感谢提示！

我取得了一些进展.关于 this 站点，我还需要 setDomStorageEnabled(true).不，我可以找到 DOM 对象并设置值，但是我没有显示修改后的站点，而是得到一个只有我设置的值的新空白站点.例如.带有文本aaa"的白色空白站点.

I got some progress. Regarding this site, I also need setDomStorageEnabled(true).No I can find the DOM object and set the value, but instead of showing the modified site I get a new blank one with only the value I set. E.g. a white blank site with the text "aaa".

推荐答案

我终于找到了解决方案！这是一种非常奇怪的行为.

Finally I found a solution! And it is a really strange behaviour.

首先你需要在你的 webview 上指定 setDomStorageEnabled(true).否则 DOM 不起作用.我想知道为什么没有教程给出提示.不过还好.

First of all you need to specify setDomStorageEnabled(true) on your webview. Otherwise the DOM doesn't work. I wonder why no tutorial gave a hint about. But ok.

myview.getSettings().setDomStorageEnabled(true);

在此之后，我最终在一个白色的空白页中，只有我设置的值.奇怪的是， javascript:document.getElementById('myfield').value = 'aaa'; 返回一个值.即我设置的那个.因此创建了一个仅包含字符串aaa"的新空白页面.

After this I ended up in a white blank page with only the value I set. The strange thing is, that javascript:document.getElementById('myfield').value = 'aaa'; returns a value. Namely the one I set. So a new blank page was created that only contains the string "aaa".

我通过修改javascript扔掉返回结果解决了:

I solved it by modifying the javascript to throw away the return result:

javascript:var x = document.getElementById('myfield').value = 'aaa';

瞧.它正在工作.

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