如何从 chrome 打包应用程序中的 web 视图中的链接打开新窗口

Question

为了显示来自横幅交换的广告，我正在加载一个包含链接到广告服务器的 iframe 的 web 视图。通过一些 javascript，我可以将广告链接目标设置为“_blank”，这样广告就会在单独的浏览器窗口中打开，否则它将在同一个小网页视图中打开。

但是它不起作用，我在控制台中得到了这个：

<webview>: A new window was blocked.

任何想法如何做到这一点？

Answer 1

问题是默认情况下，webview 不会让客人打开任意窗口。相反，它将发出一个“newwindow”事件，您可以拦截并决定如何处理它。在一个不那么可怕的形式中，这看起来像：

chrome.app.runtime.onLaunched.addListener(function() {
  chrome.app.window.create(
    'main.html',
    { 'width': 1000, 'height': 1000 },
    function(win) {
      win.contentWindow.onload = function() {
        var webview = win.contentWindow.document.querySelector('#my_webview');
        webview.addEventListener('newwindow', function(e) {
          e.preventDefault();
          // e.targetUrl contains the target URL of the original link click
          // or window.open() call: use it to open your own window to it.
          // Something to keep in mind: window.open() called from the
          // app's event page is currently (Nov 2013) handicapped and buggy
          // (e.g. it doesn't have access to local storage, including cookie
          // store). You can try to use it here and below, but be prepare that
          // it may sometimes produce bad results.
          chrome.app.window.create(e.targetUrl, ...);
        });
      };
    }
  );
});

鉴于您所描述的条件，我认为这应该适合您。

在更糟糕的情况下，某些网站可能会像这样打开新窗口/标签：

function open(href) {
    var w = window.open('', '_blank');
    w.opener = null;
    w.document.write(
      '<META HTTP-EQUIV="refresh" content="0; url=' + href + '">');
    w.document.close();
}

如果这样的网站包含在 webview 中，一切都会变得更加困难：上面的 'newwindow' 处理程序中的 e.targetUrl 将包含“about:blank”，因此无需修改代码将打开一个空白窗口/选项卡。要拦截来自访客的后续重定向，应用程序还必须使用chrome.webRequest API（文档似乎仅用于扩展，但 API 已经可用于稳定通道中的打包应用程序）：

chrome.app.runtime.onLaunched.addListener(function() {
  chrome.app.window.create(
    'main.html',
    { 'width': 2000, 'height': 1000 },
    function(win) {
      win.contentWindow.onload = function() {
        var webview = win.contentWindow.document.querySelector('#webview');
        webview.addEventListener('newwindow', function(e) {
          e.preventDefault();
          if (e.targetUrl !== 'about:blank') {
            // Easy case where the original link or window.open()
            // already contains a target URL.
            newWindow_openInTab(e.targetUrl);
          } else {
            // Harder case where the guest first opens a blank
            // window and then redirects it via a
            // 'META HTTP-EQUIV="refresh"'.
            newWindow_openInTabAndInterceptRedirect(e.window);
        });
      };
    }
  );
});

function newWindow_openInTab(url) {
  chrome.app.window.create(url, ...);
}

function newWindow_openInTabAndInterceptRedirect(newWindow) {
  // Create an invisible proxy webview to listen to redirect
  // requests from |newWindow| (the window that the guest is
  // trying to open). NOTE: The proxy webview currently has to
  // live somewhere in the DOM, so we append it to the body.
  // This requirement is in the process of being eliminated.
  var proxyWebview = document.createElement('webview');
  document.body.appendChild(proxyWebview);

  // Listen to onBeforeRequest event (chrome.webRequest API)
  // on proxyWebview in order to intercept newWindow's redirects.
  var onBeforeRequestListener = function(e) {
    // Only consider top-level non-blank redirects.
    if (e.type === "main_frame" && e.url !== 'about:blank') {
      chrome.app.window.create(e.url, ...);
      // Don't need proxyWebview anymore.
      document.body.removeChild(proxyWebview);
      // Handled this redirect: cancel further processing.
      return { cancel: true };
    } else {
      // Ignored this redirect: proceed with default processing.
      return { cancel: false };
    }
  };
  proxyWebview.onBeforeRequest.addListener(
    onBeforeRequestListener,
    { urls: [ "*://*/*" ] },
    [ 'blocking' ]
  );

  // Attach |newWindow| to proxyWebview. From the original
  // webview guest's point of view, the window is now opened
  // and ready to be redirected: when it does so, the redirect
  // will be intercepted by |onBeforeRequestListener|.
  newWindow.attach(proxyWebview);
}