早上好,我想使用我在页面上找到的写法：
https://developer.android.com/guide/topics/connectivity/nfc/advanced-nfc.html,写一个超轻的mifare.我还没有成功.
public void writeTag(Tag tag,String tagText) {
MifareUltralight ultralight = MifareUltralight.get(tag);
try {
ultralight.connect();
ultralight.writePage(4,"abcd".getBytes(Charset.forName("US-ASCII")));
ultralight.writePage(5,"efgh".getBytes(Charset.forName("US-ASCII")));
ultralight.writePage(6,"ijkl".getBytes(Charset.forName("US-ASCII")));
ultralight.writePage(7,"mnop".getBytes(Charset.forName("US-ASCII")));
} catch (IOException e) {
Log.e(TAG,"IOException while closing MifareUltralight...",e);
} finally {
try {
ultralight.close();
} catch (IOException e) {
Log.e(TAG,e);
}
}
}
我如何从主打电话给它？
我认为有必要插入一个按钮来检查标签是否存在.
我在我的活动(不是主要活动)中添加了“前台调度系统”,但是我仍然不明白如果标签存在与否,如何显示消息,在使用读写方法之前要检查什么？
package com.example.administrator.myapplication3;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.MifareUltralight;
import android.nfc.tech.Ndef;
import android.nfc.tech.NfcA;
import android.nfc.tech.NfcB;
import android.nfc.tech.NfcF;
import android.nfc.tech.NfcV;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.IOException;
import java.nio.charset.Charset;
public class DisplayMessageActivity extends AppCompatActivity {
private NfcAdapter mAdapter;
private PendingIntent pendingIntent;
private IntentFilter[] mFilters;
private String[][] mTechLists;
private static final String TAG = MainActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
// Get the Intent that started this activity and extract the string
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Capture the layout's TextView and set the string as its text
TextView textView = (TextView) findViewById(R.id.textView);
textView.setText(message);
pendingIntent = PendingIntent.getActivity( this,new Intent(this,getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP),0);
mAdapter = NfcAdapter.getDefaultAdapter(this);
pendingIntent = PendingIntent.getActivity(
this,0);
// Setup an intent filter for all MIME based dispatches
IntentFilter ndef = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
ndef.addDataType("*/*");
} catch (IntentFilter.MalformedMimeTypeException e) {
throw new RuntimeException("fail",e);
}
IntentFilter td = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
mFilters = new IntentFilter[] {
ndef,td
};
// Setup a tech list for all NfcF tags
mTechLists = new String[][] { new String[] { MifareUltralight.class.getName(),Ndef.class.getName(),NfcA.class.getName()}};
Button b = (Button) findViewById(R.id.button2);
b.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
TextView tv = (TextView) findViewById(R.id.textView);
Tag tag = getIntent().getParcelableExtra(NfcAdapter.EXTRA_TAG);
tv.setText("Click!");
//byte[] x=tag.getId();
writeTag(tag,"x");
Log.e(TAG,"cc");
}
});
}
@Override
public void onResume()
{
super.onResume();
mAdapter.enableForegroundDispatch(this,pendingIntent,mFilters,mTechLists);
}
@Override
public void onPause()
{
super.onPause();
mAdapter.disableForegroundDispatch(this);
}
@Override
public void onNewIntent(Intent intent){
// fetch the tag from the intent
Tag t = (Tag)intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
// String tlist = getTechList(t);
// android.util.Log.v("NFC","Discovered tag ["+tlist+"]["+t+"] with intent: " + intent);
// android.util.Log.v("NFC","{"+t+"}");
}
public void writeTag(Tag tag,String tagText) {
MifareUltralight ultralight = MifareUltralight.get(tag);
try {
ultralight.connect();
ultralight.writePage(4,"abcd".getBytes(Charset.forName("US-ASCII")));
ultralight.writePage(5,"efgh".getBytes(Charset.forName("US-ASCII")));
ultralight.writePage(6,"ijkl".getBytes(Charset.forName("US-ASCII")));
ultralight.writePage(7,"mnop".getBytes(Charset.forName("US-ASCII")));
} catch (IOException e) {
Log.e(TAG,e);
} finally {
try {
ultralight.close();
} catch (IOException e) {
Log.e(TAG,e);
}
}
}
public String readTag(Tag tag) {
MifareUltralight mifare = MifareUltralight.get(tag);
try {
mifare.connect();
byte[] payload = mifare.readPages(4);
return new String(payload,Charset.forName("US-ASCII"));
} catch (IOException e) {
Log.e(TAG,"IOException while writing MifareUltralight message...",e);
} finally {
if (mifare != null) {
try {
mifare.close();
}
catch (IOException e) {
Log.e(TAG,"Error closing tag...",e);
}
}
}
return null;
}
}
谢谢！
解决方法
扫描新的NFC标签后立即调用onNewIntent(Intent intent).例如,如果您想要写入每个扫描的标记,则onNewIntent()方法将如下所示：
//This method is called whenever a new tag is scanned while the activity is running
//Whatever you want to do with scanned tags,do it in here
@Override
public void onNewIntent(Intent intent){
// fetch the tag from the intent
Tag tag = (Tag)intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
//Write a String onto the tag
writeTag(tag,"Put any string here");
}
你的writeTag方法当然还没有使用它给出的字符串,但你可能知道.
如果您想要保持最新的布尔值以检查可用标记,请执行以下操作：
@Override
public void onNewIntent(Intent intent){
(new Thread(new Runnable() {
@Override
public void run() {
// fetch the tag from the intent
Tag tag = (Tag)intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
MifareUltralight myTag = MifareUltralight.get(tag);
/* Alternative to MifareUltralight:
NfcA myTag = NfcA.get(tag);
*/
myTag.connect();
while(true){
//someBoolean is just a Boolean that you can use in other threads to ask if tag is still there
someBoolean = true;
//Keep reading the tag until it ends in an exception
//when the exception occurs,you know the tag is gone
try{
myTag.transceive(new byte[] {
(byte) 0xXX,// READ command for your tag here
(byte) 0xXX,// Address of serial or UID field of your tag here
});
}catch(IOException e){
myTag.disconnect();
break;
}
}
//When loop breaks,the tag is gone,so we set the variable back to false
someBoolean = false;
}
})).start();
}
