从Android WebViewClient中的网站下载Blob文件 [英] Download Blob file from Website inside Android WebViewClient
问题描述
我有一个HTML网页，其中有一个按钮，当用户点击时会触发POST请求。请求完成后，将触发以下代码：
I have an HTML Web page with a button that triggers a POST request when the user clicks on. When the request is done, the following code is fired:
window.open(fileUrl);
浏览器中的一切都很好用，但是当在Webview组件内部实现时，新选项卡不会打开了。
Everything works great in the browser, but when implement that inside of a Webview Component, the new tab doesn't is opened.
仅供参考：在我的Android应用程序中，我设置了以下内容：
FYI: On my Android App, I have set the followings things:
webview.getSettings().setJavaScriptEnabled(true);
webview.getSettings().setSupportMultipleWindows(true);
webview.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
在 AndroidManifest.xml 我有以下权限：
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER"/>
我也尝试用 setDownloadListener 来捕获下载。另一种方法是将 WebViewClient（）替换为 WebChromeClient（），但行为是相同的。
I try too with a setDownloadListener to catch the download. Another approach was replaced the WebViewClient() for WebChromeClient() but the behavior was the same.
推荐答案
好的我在使用webview时遇到了同样的问题，我意识到WebViewClient无法像Chrome桌面客户端那样加载blob URL，我解决了它使用Javascript接口。您可以按照以下步骤执行此操作，在此应用程序中使用minSdkVersion正常工作：17。首先，通过JS转换Base64字符串中的Blob URL数据。其次，将此字符串发送到Java类，最后以可用格式转换它，在这种情况下，我将其转换为.pdf文件。
Ok I had the same problem working with webviews, I realized that WebViewClient can't load "blob URLs" as Chrome Desktop client does, I solved it using Javascript Interfaces. You can do this following these steps, is working fine in this app with minSdkVersion: 17. First, transform the Blob URL data in Base64 string trough a JS. Second, send this string to a Java Class and finally convert it in an available format, in this case I converted it in a ".pdf" file.
首先要做的事情。您必须设置您的webview，在我的情况下，我正在加载片段中的网页：
First things first. You have to setup your webview, in my case I'm loading the webpages in a fragment:
public class WebviewFragment extends Fragment {
WebView browser;
...
// invoke this method after set your WebViewClient and ChromeClient
private void browserSettings() {
browser.getSettings().setJavaScriptEnabled(true);
browser.setDownloadListener(new DownloadListener() {
@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimeType, long contentLength) {
browser.loadUrl(JavaScriptInterface.getBase64StringFromBlobUrl(url));
}
});
browser.getSettings().setAppCachePath(getActivity().getApplicationContext().getCacheDir().getAbsolutePath());
browser.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);
browser.getSettings().setDatabaseEnabled(true);
browser.getSettings().setDomStorageEnabled(true);
browser.getSettings().setUseWideViewPort(true);
browser.getSettings().setLoadWithOverviewMode(true);
browser.addJavascriptInterface(new JavaScriptInterface(getContext()), "Android");
browser.getSettings().setPluginState(PluginState.ON);
}
}
有了这个，让我们创建一个JavaScriptInterface.class，这个class将有我们的脚本将在我们的网页上执行。
Having this, lets create a JavaScriptInterface.class, this class will have our script who is going to be executed in our webpage.
public class JavaScriptInterface {
private Context context;
private NotificationManager nm;
public JavaScriptInterface(Context context) {
this.context = context;
}
@JavascriptInterface
public void getBase64FromBlobData(String base64Data) throws IOException {
convertBase64StringToPdfAndStoreIt(base64Data);
}
public static String getBase64StringFromBlobUrl(String blobUrl){
if(blobUrl.startsWith("blob")){
return "javascript: var xhr = new XMLHttpRequest();" +
"xhr.open('GET', 'YOUR BLOB URL GOES HERE', true);" +
"xhr.setRequestHeader('Content-type','application/pdf');" +
"xhr.responseType = 'blob';" +
"xhr.onload = function(e) {" +
" if (this.status == 200) {" +
" var blobPdf = this.response;" +
" var reader = new FileReader();" +
" reader.readAsDataURL(blobPdf);" +
" reader.onloadend = function() {" +
" base64data = reader.result;" +
" Android.getBase64FromBlobData(base64data);" +
" }" +
" }" +
"};" +
"xhr.send();";
}
return "javascript: console.log('It is not a Blob URL');";
}
private void convertBase64StringToPdfAndStoreIt(String base64PDf) throws IOException {
final int notificationId = 1;
String currentDateTime = DateFormat.getDateTimeInstance().format(new Date());
final File dwldsPath = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOWNLOADS) + "/YourFileName_" + currentDateTime + "_.pdf");
byte[] pdfAsBytes = Base64.decode(base64PDf.replaceFirst("^data:application/pdf;base64,", ""), 0);
FileOutputStream os;
os = new FileOutputStream(dwldsPath, false);
os.write(pdfAsBytes);
os.flush();
if(dwldsPath.exists()) {
NotificationCompat.Builder b = new NotificationCompat.Builder(context, "MY_DL");
.setDefaults(NotificationCompat.DEFAULT_ALL)
.setWhen(System.currentTimeMillis())
.setSmallIcon(R.drawable.ic_file_download_24dp)
.setContentTitle("MY TITLE")
.setContentText("MY TEXT CONTENT");
nm = (NotificationManager) this.context.getSystemService(Context.NOTIFICATION_SERVICE);
if(nm != null) {
nm.notify(notificationId, b.build());
Handler h = new Handler();
long delayInMilliseconds = 5000;
h.postDelayed(new Runnable() {
public void run() {
nm.cancel(notificationId);
}
}, delayInMilliseconds);
}
}
}
}
来源：
https://stackoverflow.com/a/41339946/4001198
https://stackoverflow.com/a/11901662/ 4001198
https://stackoverflow.com/a/ 19959041/4001198
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