FaceBook dynamic Image URL

friend's, I am working in Facebook,here i need to change the image url value string has dynamic one, here my code

intent
    .putExtra(
            "attachment",
            "{\"name\":\""
                    + Html.fromHtml(title)
                    + "\",\"href\":\""
                    + Html.fromHtml(url_val)
                    + "\",\"description\":\""
                    +  Html.fromHtml(desc_val)
                    + "\",\"media\":[{\"type\":\"image\",\"src\":\"http://www.naicu.edu/imgLib/20070913_small_seal.jpg\",\"href\":\"http://alumni.brown.edu/\"}]}");
    this.startActivityForResult(intent, MESSAGEPUBLISHED);

here image source given in code has开发者_如何学Go static,but i need to assign an simple string variable in the place of double quoted image url,for example i want to place string temp_url in the place of **src\":\"http://www.naicu.edu/imgLib/20070913_small_seal.jpg**,how can i get it.

Thanks in advance.