我是android的新手，我正在尝试使用单独的edittext字段在nfc标签中编写六个单独的字符串。我正在运行应用程序。我尝试同时写六个字符串..写完后，在阅读标签时我只能看到丢失的字符串。我怎么能分别看到所有字符串.. 下面是我的代码。
public class MainActivity extends Activity{
NfcAdapter adapter;
PendingIntent pendingIntent;
IntentFilter writeTagFilters[];
boolean writeMode;
Tag mytag;
Context ctx;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ctx=this;
Button btnWrite = (Button) findViewById(R.id.button);
final TextView plateno = (TextView)findViewById(R.id.plate_no);
final TextView model = (TextView)findViewById(R.id.model);
final TextView chasis = (TextView)findViewById(R.id.chasis_no);
final TextView engine = (TextView)findViewById(R.id.engine_no);
final TextView duedate = (TextView)findViewById(R.id.due_date);
final TextView rotexno = (TextView)findViewById(R.id.rotex_no);
btnWrite.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v) {
try {
if(mytag==null){
Toast.makeText(ctx, ctx.getString(R.string.error_detected), Toast.LENGTH_LONG ).show();
}else{
write(plateno.getText().toString(),mytag);
write(model.getText().toString(),mytag);
write(chasis.getText().toString(),mytag);
write(engine.getText().toString(),mytag);
write(duedate.getText().toString(),mytag);
write(rotexno.getText().toString(),mytag);
Toast.makeText(ctx, ctx.getString(R.string.ok_writing), Toast.LENGTH_LONG ).show();
}
} catch (IOException e) {
Toast.makeText(ctx, ctx.getString(R.string.error_writing), Toast.LENGTH_LONG ).show();
e.printStackTrace();
} catch (FormatException e) {
Toast.makeText(ctx, ctx.getString(R.string.error_writing) , Toast.LENGTH_LONG ).show();
e.printStackTrace();
}
}
});
adapter = NfcAdapter.getDefaultAdapter(this);
pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
tagDetected.addCategory(Intent.CATEGORY_DEFAULT);
writeTagFilters = new IntentFilter[] { tagDetected };
}
private void write(String text, Tag tag) throws IOException, FormatException {
NdefRecord[] records = { createRecord(text) };
NdefMessage message = new NdefMessage(records);
// Get an instance of Ndef for the tag.
Ndef ndef = Ndef.get(tag);
// Enable I/O
ndef.connect();
// Write the message
ndef.writeNdefMessage(message);
// Close the connection
ndef.close();
}
private NdefRecord createRecord(String text) throws UnsupportedEncodingException {
String lang = "en";
byte[] textBytes = text.getBytes();
byte[] langBytes = lang.getBytes("US-ASCII");
int langLength = langBytes.length;
int textLength = textBytes.length;
byte[] payload = new byte[1 + langLength + textLength];
// set status byte (see NDEF spec for actual bits)
payload[0] = (byte) langLength;
// copy langbytes and textbytes into payload
System.arraycopy(langBytes, 0, payload, 1, langLength);
System.arraycopy(textBytes, 0, payload, 1 + langLength, textLength);
NdefRecord recordNFC = new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_TEXT, new byte[0], payload);
return recordNFC;
}
@Override
protected void onNewIntent(Intent intent){
if(NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())){
mytag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
Toast.makeText(this, this.getString(R.string.ok_detection) + mytag.toString(), Toast.LENGTH_LONG ).show();
}
}
@Override
public void onPause(){
super.onPause();
WriteModeOff();
}
@Override
public void onResume(){
super.onResume();
WriteModeOn();
}
private void WriteModeOn(){
writeMode = true;
adapter.enableForegroundDispatch(this, pendingIntent, writeTagFilters, null);
}
private void WriteModeOff(){
writeMode = false;
adapter.disableForegroundDispatch(this);
}
}
布局文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Write you message: ">
</TextView>
<EditText
android:id="@+id/plate_no"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:hint="PlateNumber" />
<EditText
android:id="@+id/model"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:hint="Model" />
<EditText
android:id="@+id/chasis_no"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:hint="Chasis Number" />
<EditText
android:id="@+id/engine_no"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:hint="Engine Number" />
<EditText
android:id="@+id/due_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:hint="Due Date" />
<EditText
android:id="@+id/rotex_no"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:hint="Rotex Number" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:text="Write!!" />
</LinearLayout>
答案 0 :(得分：1)
您正在为尝试存储在NFC标签上的每个字符串使用 write（）功能。在 write（）函数中，您只需创建一个NDEFmessage，并将该消息存储到标记中。
这意味着每次调用 write（）时，都会使用新的NDEFmessage覆盖以前的NDEFmessage。结果是您只看到标签上的最后一个字符串。
要在标记上存储多个字符串（前提是标记内存足够大），您需要将所有字符串放入一个NDEFmessage并将该一条消息存储到标记中。
这意味着您应该为每个字符串创建一个NDEFrecord（例如，通过 createTextRecord（String languageCode，String text））并将它们全部放在记录数组中。现在，当您创建NDEFmessage时，所有字符串都包含在NDEFmessage中。