在android Webview中注入Javascript

Question

我想要在我的WebView中执行以下JavaScript行。

var token = top.location.href.split('access_token=')[1];
if (token) {
top.location.href = "http://example.com/index.php?token=" + token;
}

当WebView在链接中有access_token时，当用户转到此页http://examplex.com/index.php?access_token=ASDFG时，该应用会将用户重定向到另一个页面http://example.com/index.php?token=ASDFG

执行后的完整代码：

   @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_homepage);
            mWebView = (WebView) findViewById(R.id.activity_main_webview);
            // Enable Javascript
            WebSettings webSettings = mWebView.getSettings();
            webSettings.setJavaScriptEnabled(true);

        String javascriptCodeUrl= "javascript:var token = \n"+
        "top.location.href.split('access_token=')[1]; \n"+
        "if (token) { \n"+
        "top.location.href = 'http://example.com/index.php?token=' + token;}";

                    mWebView.loadUrl(javascriptCodeUrl);

            mWebView.loadUrl("http://default-webpage.com");
            // Force links and redirects to open in the WebView instead of in a browser
            mWebView.setWebViewClient(new WebViewClient());
        }