Android Java：如何让AlertDialog内WebView强制填满父布局？

问题原因 #

AlertDialog的默认视图容器自带内边距，且直接给WebView设置MATCH_PARENT布局参数时，会受容器内部布局规则限制——当网页内容高度较小时，WebView会自动收缩到内容高度，无法占满Dialog空间。

解决方案：外层嵌套LinearLayout强制占满 #

将WebView包裹在一个LinearLayout中，通过LinearLayout强制占满AlertDialog的可用空间，同时清除默认内边距，代码修改如下：

AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Age Verification");

WebView wv = new WebView(this);
wv.loadUrl({redacted});
wv.getSettings().setJavaScriptEnabled(true);
wv.setVerticalScrollBarEnabled(true);
wv.setHorizontalScrollBarEnabled(true);
wv.getSettings().setLoadWithOverviewMode(true);
wv.getSettings().setUseWideViewPort(true);
wv.setWebChromeClient(new WebChromeClient() {
    @Override
    public void onPermissionRequest(final PermissionRequest request) {
        request.grant(request.getResources());
    }
});
wv.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest url) {
        view.loadUrl(url.getUrl().toString());
        if(url.getUrl().toString().contains("/close")){
            finish();
        }
        return true;
    }
});

// 创建LinearLayout作为WebView的父容器，强制占满空间
LinearLayout container = new LinearLayout(this);
container.setLayoutParams(new ViewGroup.LayoutParams(
        ViewGroup.LayoutParams.MATCH_PARENT,
        ViewGroup.LayoutParams.MATCH_PARENT
));
container.setPadding(0, 0, 0, 0); // 清除AlertDialog默认内边距
container.addView(wv, new LinearLayout.LayoutParams(
        ViewGroup.LayoutParams.MATCH_PARENT,
        ViewGroup.LayoutParams.MATCH_PARENT
));

alert.setView(container);
alert.setNegativeButton("Close (Will void transaction if verification incomplete)", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int id) {
        startTransactionFailureDialog(VERIFICATION_FAILED);
        dialog.dismiss();
    }
});
AlertDialog result = alert.show();

Window window = result.getWindow();
window.setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);

可选优化 #

如果需要限制WebView的最大尺寸（比如原代码的0.8/0.7屏幕比例），可以替换window.setLayout的参数：

DisplayMetrics metrics = getResources().getDisplayMetrics();
int webViewHeight = (int) Math.round(0.8 * metrics.heightPixels);
int webViewWidth = (int) Math.round(0.7 * metrics.widthPixels);
window.setLayout(webViewWidth, webViewHeight);

内容的提问来源于stack exchange，提问作者Jason Chan