即使使用PowerMock也无法模拟java.net.URL？

According to my requirements, I have to upload a file to Amazon S3 by using pre-signed URL for which I got the code from the AWS website which worked for me but now I have to write JUnit for the same in which I used PowerMockito to mock java.net. URL but it's not working at all. Following is my Java code plus the JUnit which is not working. Can anyone give me solution on how should I proceed? Thanks in advance. According to my requirements, I have to upload