private Handler myhandler = new Handler() {

    @Override

    public void handleMessage(Message msg) {

        //表示隐藏添加图片按钮

        if (msg.what == 1) {

            hsv_publish_image.setVisibility(View.VISIBLE);

        } else if(msg.what==100){

        }

    }

};  

myWebView.addJavascriptInterface(new Object() {

                //显示添加图片功能

                @JavascriptInterface

                public void showAddPic(){

                    myhandler.sendEmptyMessage(1);

//                    hsv_publish_image.setVisibility(View.VISIBLE);

//                    findViewById(R.id.hsv_publish_image).invalidate();

                }

});