Getting Inputstream of a uploaded file

Can you please help me on how to get Inputstream of the file that I would be uploading using the below code. What code I need to write in my servlet

Code:

---

<form action="uploadservlet" method="post" enctype="multipart/form-data">
            <label for="filename_1">File: </label>
            <input id="filename_1" type="file" name="filename_1" size="50"/><br/>
            <label for="filename_2">File: </label>
            <input id="filename_2" type="file" name="filename_2" size="50"/><br/>
            <br/>
            <input type="submit" value="Upload File"/>
        </form>

---