我開發了一個簡單的NFC應用程序,它將在感應到NFC標籤後啓動。我想問兩個問題,爲什麼在我的程序啓動後,我需要讓設備再次檢測標籤,而不是在啓動後纔讀取標籤?而且,我將數據類型設置爲text/plain,但是爲什麼當我在textview字段中輸出數據時,出現了無意義的查詢?我的NFC讀卡器無法成功讀取正確的數據
public class Reader extends Activity {
TextView mText;
NfcAdapter mAdapter;
PendingIntent mPendingIntent;
IntentFilter mFilters[];
String mTechLists[][];
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onStart(){
super.onStart();
setContentView(R.layout.activity_reader);
mText = (TextView) findViewById(R.id.text);
mAdapter = NfcAdapter.getDefaultAdapter(this);
mPendingIntent = PendingIntent.getActivity(this, 0,
new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
IntentFilter ndef = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try{
ndef.addDataType("text/plain");
}catch(MalformedMimeTypeException e){
throw new RuntimeException("fail", e);
}
IntentFilter nt = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
mFilters = new IntentFilter[]{
ndef, nt
};
mTechLists = new String[][]{
new String[]{
Ndef.class.getName()
}
};
Intent intent = getIntent();
mText.setText(getNdefMessages(intent));
}
public String getNdefMessages(Intent intent){
NdefMessage[] msgs = null;
String action = intent.getAction();
if(NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)||
NfcAdapter.ACTION_TAG_DISCOVERED.equals(action)){
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if(rawMsgs != null){
msgs = new NdefMessage[rawMsgs.length];
for(int i=0; i<rawMsgs.length; i++){
msgs[i] = (NdefMessage) rawMsgs[i];
}
}else{
byte[] empty = new byte[]{};
NdefRecord record = new NdefRecord(NdefRecord.TNF_UNKNOWN, empty, empty, empty);
NdefMessage msg = new NdefMessage(new NdefRecord[]{record});
msgs = new NdefMessage[]{msg};
}
}
if(msgs==null)
return "No Tag discovered!";
else
return msgs.toString();
}
@Override
public void onResume(){
super.onResume();
if (mAdapter != null)
mAdapter.enableForegroundDispatch(this, mPendingIntent, mFilters, mTechLists);
}
@Override
public void onPause(){
super.onPause();
if (mAdapter != null)
mAdapter.disableForegroundDispatch(this);
}
@Override
public void onNewIntent(Intent intent){
Log.i("Foreground dispatch", "Discovered tag with intent:" + intent);
mText = (TextView) findViewById(R.id.text);
mText.setText(getNdefMessages(intent));
}
}
以上是我的主要程序,下面是清單文件:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="android.reader"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk
android:minSdkVersion="10"
android:targetSdkVersion="15" />
<uses-permission
android:name="android.permission.NFC"/>
<uses-feature
android:name="android.hardware.nfc"
android:required="true"/>
<application android:label="@string/app_name"
android:icon="@drawable/ic_launcher"
android:theme="@style/AppTheme"
android:debuggable="true">
<activity
android:name=".Reader"
android:label="@string/title_activity_reader">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED"/>
<data android:mimeType="text/plain" />
<!--<data
android:scheme="http"
android:host="developer.android.com"/>-->
<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>
<intent-filter>
<action android:name="android.nfc.action.TAG_DISCOVERED"/>
<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>
</activity>
</application>
</manifest>
消息顯示在應用程序:
最後是數據I輸入該標籤:
通過谷歌,我終於找到了這種方法來訪問playload,但是當我有兩個記錄甚至更多,有什麼方法來獲取這些記錄,我試圖通過消息得到第二個。[1] .getRecords( )[0] .getPayload(),但系統回覆我索引出界 – Conrad 2012-07-17 08:38:31
我試圖輸出rawMsgs和Msgs [0] .getReord()的長度都是長度爲1的一些值,請問哪裏是第二張唱片? – Conrad 2012-07-17 08:55:16
有一個NDEF消息有多個記錄,所以'msgs [0] .getRecords()[1]'是第一個(也是唯一的)NDEF消息的第2條記錄。 – 2012-07-17 09:04:46