Upload an Image from camera or gallery in WebView

Question

WebView in this app opens a page with upload button.

Below is th

Answer 1

Update 6/18: This doesn't seem to work on Samsung Galaxy S2 with Android 4.2.1. This worked fine on HTC One X+ with 4.1.2. Be cautioned.

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I faced the same problem. Here's the problem and how I solved it.

Problem:

When openFileChooser is called, the call back object ValueCallback is being passed. This is the actual call back to web view when we have a file ready for it. We save this object to mUploadMessage and use mUploadMessage.onReceiveValue() function in onActivityResult to return the file to Webview. While you choose camera, click a picture, save it and return to the webview activity, our activity might get recycled, which means we actually lose the call back object mUploadMessage. And hence, the file cannot be passed back to webview for upload.

Fix:

Fix involves executing some javascript, so enable javascript on webview. Basically, we will get another call back object if we lost the previous one.

We need to create a boolean field 'mUploadFileOnLoad' and three fields.

    private int mReturnCode;
    private int mResultCode;
    private Intent mResultIntent;
    private boolean mUploadFileOnLoad = false;

When we return to our activity from camera, onActivityResult will be called. If activity is reconstructed, mUploadMessage is null. So, we will save the parameters to fields and set mUploadFileOnLoad to true and return. The else part is very important.

    @Override
    protected void onActivityResult(int requestCode, 
                                    int resultCode,
                                    Intent intent) 
    {  
      //if the callback object has been recycled      
      if(null==mUploadMessage)
      {
        //Save the result
        mReturnCode = requestCode;
        mResultCode = resultCode;
        mResultIntent = intent;
        //remember to invoke file upload using Javascript
        mUploadFileOnLoad = true;
        return;
      }else
        mUploadFileOnLoad = false;
      //rest of the code
    }

The important parts of this solution are in WebViewClient and WebChromeClient

    new WebChromeClient() {

        //Other overloaded functions

        //See http://stackoverflow.com/a/15423907/375093 for full explanation
        //The undocumented magic method override
        //Eclipse will swear at you if you try to put @Override here
        // For Android < 3.0
        public void openFileChooser(ValueCallback uploadMsg) {
            //If we lost the callback object
            if(mUploadFileOnLoad)
            {
                mUploadMessage = uploadMsg;
                //use the saved result objects to invoke onActivityResult
                onActivityResult(mReturnCode, mResultCode, mResultIntent);
                return;
            }
         //Rest of the code....
         }

and

        new WebViewClient() {
        @Override
        public void onPageFinished(WebView view, String url) {
            if(mUploadFileOnLoad)
            {
               webview.loadUrl("javascript:document.getElementById('my_file').click()");
            }
        }

In the above, my_file is the id of the element in the web page.

So, in summary, what we did is - When we don't have a callback object, we save the data received from other activity and set mUploadFileOnLoad to true and wait for page to load. When page loads, we use Javascript to invoke the file chooser so we get a callback object. Since we already have results, we invoke onActivityResult and return. onActivityResult now has a callback from the webview.