【移动应用开发技术】Android NFC开发中Mifare Tag读写的示例分析

【移动应用开发技术】AndroidNFC开发中MifareTag读写的示例分析

本篇文章为大家展示了AndroidNFC开发中MifareTag读写的示例分析，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。针对常用的MifareTag具体说明。MifareTag可以有1K,2K,4K，其内存分区大同小异，下图给出了1K字节容量的Tag的内存分布：数据分为16个区(Sector),每个区有4个块(Block)，每个块可以存放16字节的数据，其大小为16X4X16=1024bytes。每个区***一个块称为Trailer，主要用来存放读写该区Block数据的Key，可以有A，B两个Key，每个Key长度为6个字节，缺省的Key值一般为全FF或是0.由MifareClassic.KEY_DEFAULT定义。因此读写MifareTag首先需要有正确的Key值（起到保护的作用），如果鉴权成功：auth

=

mfc.authenticateSectorWithKeyA(j,

MifareClassic.KEY_DEFAULT);然后才可以读写该区数据。本例定义几个Mifare相关的类MifareClassCard，MifareSector,MifareBlock和MifareKey以方便读写MifareTag.Android系统来检测到NFCTag，将其封装成Tag类，存放到Intent的NfcAdapter.EXTRA_TAGExtra数据包中，可以使用MifareClassic.get(Tag)获取对象的MifareClassic类。Tag

tagFromIntent

=

intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

//

4)

Get

an

instance

of

the

Mifare

classic

card

from

this

TAG

//

intent

MifareClassic

mfc

=

MifareClassic.get(tagFromIntent);下面为读取Mifarecard的主要代码：//

1)

Parse

the

intent

and

get

the

action

that

triggered

this

intent

String

action

=

intent.getAction();

//

2)

Check

if

it

was

triggered

by

a

tag

discovered

interruption.

if

(NfcAdapter.ACTION_TECH_DISCOVERED.equals(action))

{

//

3)

Get

an

instance

of

the

TAG

from

the

NfcAdapter

Tag

tagFromIntent

=

intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

//

4)

Get

an

instance

of

the

Mifare

classic

card

from

this

TAG

//

intent

MifareClassic

mfc

=

MifareClassic.get(tagFromIntent);

MifareClassCard

mifareClassCard=null;

try

{

//

5.1)

Connect

to

card

mfc.connect();

boolean

auth

=

false;

//

5.2)

and

get

the

number

of

sectors

this

card

has..and

loop

//

thru

these

sectors

int

secCount

=

mfc.getSectorCount();

mifareClassCard=

new

MifareClassCard(secCount);

int

bCount

=

0;

int

bIndex

=

0;

for

(int

j

=

0;

j

<

secCount;

j++)

{

MifareSector

mifareSector

=

new

MifareSector();

mifareSector.sectorIndex

=

j;

//

6.1)

authenticate

the

sector

auth

=

mfc.authenticateSectorWithKeyA(j,

MifareClassic.KEY_DEFAULT);

mifareSector.authorized

=

auth;

if

(auth)

{

//

6.2)

In

each

sector

-

get

the

block

count

bCount

=

mfc.getBlockCountInSector(j);

bCount

=Math.min(bCount,

MifareSector.BLOCKCOUNT);

bIndex

=

mfc.sectorToBlock(j);

for

(int

i

=

0;

i

<

bCount;

i++)

{

//

6.3)

Read

the

block

byte

[]data

=

mfc.readBlock(bIndex);

MifareBlock

mifareBlock

=

new

MifareBlock(data);

mifareBlock.blockIndex

=

bIndex;

//

7)

Convert

the

data

into

a

string

from

Hex

//

format.

bIndex++;

mifareSector.blocks<i>

=

mifareBlock;

}

mifareClassCard.setSector(mifareSector.sectorIndex,

mifareSector);

}

else

{

//

Authentication

failed

-

Handle

it

}

}

ArrayList<String>

blockData=new

ArrayList<String>();

int

blockIndex=0;

for(int

i=0;i<secCount;i++){

MifareSector

mifareSector=mifareClassCard.getSector(i);

for(int

j=0;j<MifareSector.BLOCKCOUNT;j++){

MifareBlock

mifareBlock=mifareSector.blocks[j];

byte

[]data=mifareBlock.getData();

blockData.add("Block

"+

blockIndex++

+"

:

"+

Converter.getHexString(data,

data.length));

}

}

String

[]contents=new

String[blockData.size()];

blockData.toArray(contents);

setListAdapter(new

ArrayAdapter<String>(this,

android.R.layout.simple_list_item_1,

contents));

getListView().setTextFilterEnabled(true)