i have nexus s, nexus 4 and 6 mifare nfc tags, and want to make an desktop application with nfc reader/writer acr122u device (which i haven't bought it yet).
But apart from android sdk, is there some other SDK needed for making an desktop application through eclipse with java? or i can directly buy and use the acr122u device (without sdk) and make the app through eclipse?
If the SDK is needed, is there any link to download it for free or i have to buy it from the vendor itself?
One more thing, does nexus S and ACR122U support felica nfc cards?
I have mifare classic nfc cards, its working fine with them.
To develop applications for the ACR122U you do not need to purchase the SDK from ACS. From a computing/development perspective, the ACR122U is a smartcard reader/writer.
To develop with Java you will need the ACR122U drivers and to code against the Java Smart Card I/O API
The SDK on offer from ACS is simply just a collection of sample code for various platforms (Java, C#.NET, VB6, C++) It is not a requirement to interface with the device.
Here is some sample code which looks like it could be useful to you. What exactly are you trying to achieve.
Finally, if you are interested in .NET dev then look at the CardWerk Smart Card API for .NET. I used this and it greatly simplified things as interfacing with winscard.dll seemeed like a lot of work.
来源：https://stackoverflow.com/questions/15453709/is-sdk-for-nfc-reader-writer-acr122u-device-required-to-build-read-write-applica