DNS Filter

Now I need a program which I call it DNS filter program,and I have a file called FilterTable.txt(Attachments).The functions of the program are as follows.I open an Internet exporer,if I keyin "www.hit.edu.cn"(its ip is 219.217.227.180),the program will search FilterTable and access google'DNS 8.8.4.4 to parse the site.But if I keyin "www.baidu.com",the program will search TilterTable.txt and return "cannot access!".
How can I write the program using java? Vvvvvvvvvvvvvvery thank you!

You're talking about an HTTP proxy. Instead of wring it from scratch, why not use an existing one? There used to be one called "Muffin", although it's probably outdated now. But a web search will find others. Any particular reason it needs to be written in Java?

Thank you for your answer.Its my homework that I will post it to my teacher.Muffin is comlex.I want to an very simple one.Could you help me?

Well, if it's homework then you should be doing it in the first place. What do you have so far, and where are you stuck making progress?

You said you were writing a program, but then you started talking about what Internet Explorer should do. I don't understand how those two things are related.