Download file generated by javascript in android webview

Question

I have an android app with a webview.

Whenever a user clicks on a button, JavaScript creates a blob, puts text in it and downloads it.

Here's the function that does this:

function saveTextAsFile(A)
{
    FillTextToWrite(A);
    var textFileAsBlob = new Blob([textToWrite], {
        type: 'text/plain'
    });
    var downloadLink = document.createElement("a");
    downloadLink.download = "Analysis.txt";
    downloadLink.innerHTML = "Download File";
    if (window.webkitURL != null)
    {
        downloadLink.href = window.webkitURL.createObjectURL(textFileAsBlob);
    }
    else
    {
        downloadLink.href = window.URL.createObjectURL(textFileAsBlob);
        downloadLink.onclick = destroyClickedElement;
        downloadLink.style.display = "none";
        document.body.appendChild(downloadLink);
    }

    downloadLink.click();
}

It works fine in any browser, but when I try to download it in the app, nothing happens.

Is there a way to download the blob in the app or is it easier to change the JavaScript?

I need the JavaScript to work on browser as well as on the android app, so sending the blob to the android app in JavaScript will not work on browser.

Maybe this question/answers will help. stackoverflow.com/questions/33434532/… — bobjoe
– bobjoe, Commented Jan 11, 2017 at 14:40
@bobjoe Thank you for your answer, but it is solved. I forgot about this question but I will answer my solution. — Laura
– Laura, Commented Jan 11, 2017 at 14:43

Laura · Accepted Answer · 2017-01-11 14:50:23Z

1

The solution I found was to detect wheter the javascript is running in Android app or in browser (by adding a string to the user agent).

When in Android app I am sending variable textToWrite (which would normally go into the blob) to the java.

In javascript:

if(App){
    Android.sendData(textToWrite);
} else {//make blob}

In java:

myWebView.addJavascriptInterface(new myJavascriptInterface(this), "Android");

public class myJavascriptInterface {
    Context mContext;

    myJavascriptInterface(Context c) {
        mContext = c;
    }

    @JavascriptInterface
    public void sendData(String data) {
        //save data as file
    }
}

answered Jan 11, 2017 at 14:50

Laura

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2 Comments

Surendra Over a year ago

What about IOS??

Laura Over a year ago

@Jacksonmj the app was not written for iOS

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