禁用WebView中的缓存,Cookie和其他所有内容

Question

我有一个web服务,我试图在后台使用webview进行身份验证.当我最初发送请求时,它将正常工作(基于凭据的失败/成功),但看起来我似乎得到了缓存响应.

这是我的webview设置代码:

WebView browser = new WebView(this);
WebSettings settings = browser.getSettings();
settings.setJavaScriptEnabled(true);
settings.setSavePassword(false);
settings.setCacheMode(WebSettings.LOAD_NO_CACHE);
settings.setAppCacheEnabled(false);
browser.setWebChromeClient(new WebChromeClient() {
    public void onProgressChanged(WebView view, int progress) {
    Log.d("BROWSERPROGRESS", Integer.toString(progress));
}
});
jsInterface = new AddAccountJSInterface();
browser.addJavascriptInterface(jsInterface, "ADDACCOUNTJSINTERFACE");
browser.setWebViewClient(new AddAccountClient(this));

因此,您可能会看到我有两个额外的类来控制我的webView:

1. 为javascript提供接口的对象(AddAccountJSInterface)
2. WebViewClient

另外我有一个WebChromeClient,但它只用于调试,我很确定它不会干扰任何事情.

JS界面简单地提供了一种简单的方法来获取正文HTML以进行分析,所以我相信这也不是问题.

WebViewClient中包含以下代码,该代码根据来自Web服务的各种响应执行大部分"自定义"工作.

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if(url.contains(INSTALL_PREFIX)) {
            HashMap<String, String> params = extractParameters(url);
            verificationComplete(params);
            return true;
        }
        return false;
    }

    @Override
    public void onPageFinished(WebView view, String url){
        if(invalidShop(view)) {
            Toast.makeText(context, context.getString(R.string.no_find_shop), Toast.LENGTH_SHORT).show();
            shopAddressField.requestFocus();
            replaceUiElements(loadingBar, addAccountButton);
        } else if(url.contains(ADMIN_AUTH_LOGIN)) {
            if(invalidLogin(view)) {
                Toast.makeText(context, context.getString(R.string.invalid_login),Toast.LENGTH_SHORT).show();
                emailField.requestFocus();
                replaceUiElements(loadingBar, addAccountButton);
            } else {
                String email = emailField.getText().toString();
                String password = passwordField.getText().toString();
                String submitJS = String.format(FORM_SUBMISSION_JS, email, password);

                jsInterface.setInnerHTML("");

                browser.loadUrl(submitJS);
            }
        }
    }

在我的活动中,我需要填写3个文本字段,然后单击按钮进行提交.然后,活动从3个文本字段(shopAddressField,usernameField,passwordField)中获取数据,然后执行一些填充某些表单数据的javascript(在不可见的webView中加载),然后单击提交按钮.

这是最后一个搞乱的部分,似乎是缓存来自服务器的响应(可能使用cookie？)并返回而不是询问服务器数据是否正确.

一点澄清:

JSInterface只是一个Java对象,它允许我在我的webview上执行javascript,它与该对象中的一个函数相关联.在我的例子中,我的JSInterface有一个函数是setInnerHtml(String html).

这是在webview上执行的javascript:

javascript:window.ADDACOUNTJSINTERFACE.setInnerHTML(document.body.innerHTML)

这是setInnerHtml函数:

public void setInnerHtml(String innerHtml) {
    this.innerHtml = innerHtml;
}

因此,当我实际执行jsInterface.setInnerHtml("")时,我只是覆盖了所引入的HTML(为了确保我没有从那里获取旧数据).

至于我的submitJS,它再次是我在webView上执行的一些Javascript,如下所示:

// submitJS will be something like this once all the credentials have been set
// Note: I know that the server will make jQuery available
// Note: Much of the Java string formatting has been removed to help clarify
// the code.
String submitJS = 
    "javascript:(function() {
        $('login-input').value='username';
        $('password').value='password';
        $('sign-in-form').up().submit();
    })()"
// I then simply get the webview to execute the javascript above
webView.loadData(submitJS);

Answer 1

所以事实证明问题不是基于缓存，也可能不是 cookie。

当在 webView 上执行 javascript 时，它会在单独的线程中执行此操作，并且速度可能会很慢。这会导致竞争条件，导致代码以错误的顺序执行。

我通过使用信号量作为互斥体解决了这个问题。这允许我阻止 getter 在 webView 上的 Javascript 能够执行之前返回。

我现在创建的界面如下所示：

private class AddAccountJSInterface {
    private final String TAG = getClass().getName().toUpperCase();
    private Semaphore mutex = new Semaphore(1, false);
    private String innerHTML;

    public void aquireSemaphore() {
        Log.d(TAG, "Attempting to lock semaphore");
        try {
            mutex.acquire();
        } catch(InterruptedException e) {
            Log.d(TAG, "Oh snap, we got interrupted.  Just going to abort.");
            return;
        }
        Log.d(TAG, "Semaphore has been aquired");
    }

    @SuppressWarnings("unused")
    public void setInnerHTML(String html) {
            this.innerHTML = html;
            Log.d(TAG, "setInnerHTML is now releasing semaphore.");
            mutex.release();
            Log.d(TAG, "setInnerHTML has successfully released the semaphore.");
    }

    public synchronized String getInnerHTML() {
        Log.d(TAG, "getInnerHTML attempting to aquire semaphore, may block...");
        String innerHTML = "";
        try {
            mutex.acquire();

            Log.d(TAG, "getInnerHTML has aquired the semaphore, grabbing data.");
            innerHTML = this.innerHTML;

            Log.d(TAG, "getInnerHTML no longer needs semaphore, releasing");
            mutex.release();
        } catch (InterruptedException e) {
            Log.d(TAG, "Something has gone wrong while attempting to aquire semaphore, aborting");
        }

        return innerHTML;
    }
}

现在我在代码中使用它的方式如下：

// I have access to the jsInterface object which is an instance of the class above as well as a webView which I will be executing the javascript on.
String getInnerHtmlJS = "javascript:window.MYJSINTERFACE.setInnerHTML(document.body.innerHTML);"
jsInterface.aquireSemaphore()
// Execute my JS on the webview
jsInterface.loadUrl(getInnerHtmlJS)
// Now we get our inner HTML
// Note: getInnerHTML will block since it must wait for the setInnerHTML (executed via the JS) function to release the semaphore
String theInnerHTML = jsInterface.getInnerHTML();