如何在 onNewIntent 执行之前拦截 NFC 标签
how to intercept NFC tag before onNewIntent executes
我有一个应用程序可以捕获 NFC 标签。我过去遇到的问题是用户以不稳定的方式将鼠标悬停在标签上，导致 NFC 适配器触发两次。
我做了一些事情来解决这个问题。
清单：
<activity
android:name=".NfcActivity"
android:screenOrientation="portrait"
android:launchMode="singleTask"
android:noHistory="true"
android:configChanges="mcc|mnc|locale|touchscreen|keyboard|keyboardHidden|navigation|screenLayout|fontScale|uiMode|orientation">
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="text/plain" />
</intent-filter>
</activity>
这会将 NFC 捕获 Activity 设置为堆栈中的唯一实例，并且没有历史记录。我已经覆盖了所有可以停止和重新启动此 activity 的配置更改，后者可能导致意图数据重新传送到 activity，使其看起来像重复扫描。
在 Activity 本身中，我已经覆盖了 onNewIntent，除了显示错误的扫描屏幕外什么都不做。我也明白 onNewIntent 应该从功能的角度反映 onCreate，但是因为以前版本的应用程序已经向下一个 Activity 发送了 2 次扫描，我只希望 NFC 捕获代码在一个地方，onCreate。
在 onCreate 中，我做了进一步的测试，以防止将鼠标悬停在标签上并创建错误的扫描。
- 我检查了 Intent 中启动的表单历史标志。 Android 可以在内存不足时终止应用程序，并在稍后重新启动重新交付原始意图。这可能会导致看起来像是重复扫描。
- 在 onCreate 中，我检查用户是否仍然有 phone 连接到标签。这证明用户没有将鼠标悬停在带有 ndefTag.connect();
的标签上
该应用程序似乎运行良好，但在一个特定的 phone（三星 Galaxy Young 2）上，如果用户将 phone 放在标签上几秒钟，NFC 适配器似乎连续开火几次。
发生这种情况时，原始扫描将被取消。这样做的原因是 oncreate 处理标签但是当后续扫描发生时（通过悬停，偶然）， onPause -> onNewIntent 运行。所以 Activity 跳出 onCreate 并停止处理标签。 onNewIntent 显示失败的扫描屏幕并启动菜单屏幕。
以上不是什么大问题，因为用户必须重新扫描标签。
我希望发生的事情是：
当 onCreate 运行时，无论如何处理标签，即使 onNewintent 执行。有没有办法在到达 onNewintent 和 onPause 之前拦截意图？
也许有一个我可以使用的全局标志，可以先检查它以说明 onCreate 仍然是 运行 而 onNewIntent 不应该，或者更重要的是 onPause 没有被调用使 onCreate 停止 运行.
import java.util.List;
import java.util.concurrent.ExecutionException;
import org.ndeftools.Message;
import org.ndeftools.Record;
import android.app.Activity;
import android.app.PendingIntent;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Parcelable;
import android.os.Vibrator;
import android.util.Log;
import android.widget.Toast;
public class NfcActivity extends Activity {
private static final String TAG = NfcActivity.class.getName();
protected NfcAdapter nfcAdapter;
protected PendingIntent nfcPendingIntent;
Handler handler;
Runnable runnable;
Handler failHandler;
Runnable failRunnable;
Parcelable[] messages;
Intent i;
Tag tag;
String tagId;
boolean nfcConnected;
ProgressDialog progressDialog;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.nfcactivitylayout);
Log.e(TAG, "oncreate");
nfcConnected = false;
// initialize NFC
nfcAdapter = NfcAdapter.getDefaultAdapter(this);
nfcPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, this.getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
tag = null;
tagId = null;
i = getIntent();
if ((i.getFlags() & Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY) != 0) {
//check to see if Android has previously killed the app and relaunched it from History
//and delivered the original intent.
//if it has do not process and launch the menu screen
Intent processPayloadIntent = new Intent(NfcActivity.this, NfcscannerActivity.class);
processPayloadIntent.setAction("QRCODE_ACTION");
processPayloadIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(processPayloadIntent);
}else{
tag = i.getParcelableExtra(NfcAdapter.EXTRA_TAG);
tagId = bytesToHexString(tag.getId());
Log.e(TAG, "tagID = " + tagId);
Log.e(TAG, "oncreate intent action = " + i.getAction());
//The activity has captured tag data, prove the user is not hovering over the tag and is doing a good scan
//hovering can trigger the adapter twice
AsyncNfcConnect asnc = new AsyncNfcConnect();
try {
asnc.execute().get();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Log.e(TAG, "nfcConnected!!!!!!!!!!!!!!!!!!!!!!!!! = " + nfcConnected);
if(nfcConnected == true){
int buildVersionSdk = Build.VERSION.SDK_INT;
int buildVersionCodes = Build.VERSION_CODES.GINGERBREAD;
Log.e(TAG, "buildVersionSdk = " + buildVersionSdk
+ "buildVersionCodes = " + buildVersionCodes);
int themeVersion;
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.GINGERBREAD) {
themeVersion = 2;
} else {
themeVersion = 1;
}
try{
progressDialog = new ProgressDialog(this, themeVersion);
progressDialog.setTitle("NFC Tag Scanned");
progressDialog.setMessage("Processing tag...");
progressDialog.setIndeterminate(true);
progressDialog.show();
}catch(Exception e){ }
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(i.getAction()) || NfcAdapter.ACTION_TAG_DISCOVERED.equals(i.getAction())) {
if(NfcScannerApplication.isCanScanNfcTag()){
messages = i.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (messages != null) {
//setContentView(R.layout.successfulnfc);
NfcScannerApplication.startNfcTimer();
//Toast.makeText(this, "NFC timer set", Toast.LENGTH_LONG).show();
Log.e(TAG, "Found " + messages.length + " NDEF messages"); // is almost always just one
vibrate(); // signal found messages :-)
initHandler();
handler.postDelayed(runnable, 2000);
}else{
Toast.makeText(this, "Data on tag was not correct", Toast.LENGTH_LONG).show();
try{
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}else{
try{
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
} else {
Toast.makeText(this, "Tag not recognized correctly", Toast.LENGTH_LONG).show();
try{
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}else{
try{
Toast.makeText(this, "Phone wasn't connected to Tag", Toast.LENGTH_LONG).show();
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}//end of NFC connect test
}//end of launched from history check
}//end of onCreate
@Override
protected void onStart() {
super.onStart();
Log.e(TAG, "onStart");
}
@Override
protected void onStop() {
super.onStop();
Log.e(TAG, "onStop");
}
@Override
public void onNewIntent(Intent intent) {
Log.e(TAG, "onNewIntent");
Toast.makeText(this, "Bad scan!!!", Toast.LENGTH_LONG).show();
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}//end of onNewIntent
public void enableForegroundMode() {
Log.e(TAG, "enableForegroundMode");
IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED); // filter for all
IntentFilter[] writeTagFilters = new IntentFilter[] {tagDetected};
nfcAdapter.enableForegroundDispatch(this, nfcPendingIntent, writeTagFilters, null);
}
public void disableForegroundMode() {
Log.e(TAG, "disableForegroundMode");
nfcAdapter.disableForegroundDispatch(this);
}
@Override
protected void onResume() {
super.onResume();
Log.e(TAG, "onResume");
enableForegroundMode();
}
@Override
protected void onPause() {
Log.e(TAG, "onPause");
super.onPause();
disableForegroundMode();
if(handler != null){
handler.removeCallbacks(runnable);
}
}
private void vibrate() {
Log.e(TAG, "vibrate");
Vibrator vibe = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE) ;
vibe.vibrate(500);
}
public void initHandler(){
handler = new Handler();
runnable = new Runnable() {
public void run() {
processTag();
}
private void processTag() {
Log.e(TAG, "about to process tag");
try{
progressDialog.dismiss();
}catch(Exception e){
//do nothing
}
// parse to records
for (int i = 0; i < messages.length; i++) {
try {
List<Record> records = new Message((NdefMessage)messages[i]);
Log.e(TAG, "Found " + records.size() + " records in message " + i);
for(int k = 0; k < records.size(); k++) {
Log.e(TAG, " Record #" + k + " is of class " + records.get(k).getClass().getSimpleName());
Record record = records.get(k);
NdefRecord ndefRecord = record.getNdefRecord();
byte[] arr = ndefRecord.getPayload();
String payload = new String(arr);
if(payload.length() > 0){
payload = payload.substring(3, payload.length());
Log.e(TAG, "payload = " + payload);
String[] splitPayload = payload.split(",");
String tagType = splitPayload[0];
String tagCompany = splitPayload[1];
String tagClientID = splitPayload[2];
String tagClientName = splitPayload[3];
if(! tagClientID.equalsIgnoreCase("0") && tagClientID.length() > 0){
handler.post(new Runnable(){
public void run() {
setContentView(R.layout.successfulnfc);
}
});
Intent processPayloadIntent = new Intent(NfcActivity.this, NfcscannerActivity.class);
processPayloadIntent.putExtra("payload", payload);
processPayloadIntent.putExtra("tagid", tagId);
processPayloadIntent.setAction("NFC");
processPayloadIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
//processPayloadIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP|Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(processPayloadIntent);
finish();
overridePendingTransition(0, R.anim.activity_animation_zoom_in);
}else{
Toast.makeText(NfcActivity.this, "Tag data problem/Scan problem.", Toast.LENGTH_LONG).show();
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}else{
Toast.makeText(NfcActivity.this, "Tag data problem/Scan problem.", Toast.LENGTH_LONG).show();
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}
} catch (Exception e) {
Log.e(TAG, "Problem parsing message", e);
}
}
}
};
}
public void initFailHandler(){
failHandler = new Handler();
failRunnable = new Runnable() {
public void run() {
returnToMainMenu();
}
private void returnToMainMenu() {
//Log.e(TAG, "about to return to main menu");
try{
progressDialog.dismiss();
}catch(Exception e){
//do nothing
}
Toast.makeText(NfcActivity.this, "Please check your scanning technique.\nPlease do not hover over tag or swipe...", Toast.LENGTH_LONG).show();
failHandler.post(new Runnable(){
public void run() {
setContentView(R.layout.nfcfail);
}
});
//onBackPressed();
Intent processPayloadIntent = new Intent(NfcActivity.this, NfcscannerActivity.class);
processPayloadIntent.setAction("QRCODE_ACTION");
processPayloadIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(processPayloadIntent);
finish();
//overridePendingTransition(0, R.anim.activity_animation_zoom_in);
}
};
}
private String bytesToHexString(byte[] src) {
StringBuilder stringBuilder = new StringBuilder("0x");
if (src == null || src.length <= 0) {
return null;
}
char[] buffer = new char[2];
for (int i = 0; i < src.length; i++) {
buffer[0] = Character.forDigit((src[i] >>> 4) & 0x0F, 16);
buffer[1] = Character.forDigit(src[i] & 0x0F, 16);
System.out.println(buffer);
stringBuilder.append(buffer);
}
return stringBuilder.toString();
}
private class AsyncNfcConnect extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
NfcActivity.this.nfcConnected = false;
String result;
Ndef ndefTag = Ndef.get(tag);
try {
Log.e(TAG, "about to test connect()********************************************");
ndefTag.connect(); // this should already perform an IO operation and should therefore fail if there is no tag
Log.e(TAG, "Ndef.connect() connected!********************************************");
NdefMessage ndefMsg = ndefTag.getNdefMessage(); // this reads the current NDEF message from the tag and consequently causes an IO operation
NfcActivity.this.nfcConnected = true;
result = "OK";
return result;
} catch (Exception e) {
// there is no tag or communication with tag dropped
Log.e(TAG, "There a problem with connecting to the tag using Ndef.connect(");
NfcActivity.this.nfcConnected = false;
result = "NOTOK";
return result;
} finally {
try {
ndefTag.close();
} catch (Exception e) {
}
}
}
}//end of Async
}
您似乎坚持不在 onNewIntent() 中处理 NFC 意图。我建议 onCreate() 和 onNewIntent() 都调用扫描标签的通用过程。这样，两个入口点将遵循相同的代码路径。
您声称应用程序 "jumps out of onCreate" 可能只是一种修辞手法？发生的情况是您的标签扫描 AsyncNfcConnect 运行s 在单独的线程上作为后台任务（应该如此）。该任务在 onCreate() 中创建，并在 onCreate() 完成后继续 运行ning（您可以在 onCreate() 末尾添加一个 Log 语句来检查） .当与标签的连接以某种方式丢失并重新发现标签时，如您所见，将调用 onNewIntent()。
无论如何都无法阻止这种情况的发生，因此您的应用程序必须能够处理它。要检测并处理它，您可以在 activity 中设置一些标志，以指示您的后台任务正在 运行ning 或有 运行。您还可以存储是否发生异常的信息，并在重新发现时再次尝试扫描标签（这可能需要您实施我上面提出的建议）。如果您想让您的应用程序更加防故障，您还可以存储最后一次扫描标签的 ID，以便在您成功扫描（或未扫描）后重新发现它时再次肯定地识别它。当同一个标签不断出现异常时，您可以在一定次数后向用户指示他（例如，建议将设备放置在不同的位置 w.r.t。标签）。
我有一个应用程序可以捕获 NFC 标签。我过去遇到的问题是用户以不稳定的方式将鼠标悬停在标签上，导致 NFC 适配器触发两次。
我做了一些事情来解决这个问题。
清单：
<activity
android:name=".NfcActivity"
android:screenOrientation="portrait"
android:launchMode="singleTask"
android:noHistory="true"
android:configChanges="mcc|mnc|locale|touchscreen|keyboard|keyboardHidden|navigation|screenLayout|fontScale|uiMode|orientation">
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="text/plain" />
</intent-filter>
</activity>
这会将 NFC 捕获 Activity 设置为堆栈中的唯一实例，并且没有历史记录。我已经覆盖了所有可以停止和重新启动此 activity 的配置更改，后者可能导致意图数据重新传送到 activity，使其看起来像重复扫描。
在 Activity 本身中，我已经覆盖了 onNewIntent，除了显示错误的扫描屏幕外什么都不做。我也明白 onNewIntent 应该从功能的角度反映 onCreate，但是因为以前版本的应用程序已经向下一个 Activity 发送了 2 次扫描，我只希望 NFC 捕获代码在一个地方，onCreate。
在 onCreate 中，我做了进一步的测试，以防止将鼠标悬停在标签上并创建错误的扫描。
- 我检查了 Intent 中启动的表单历史标志。 Android 可以在内存不足时终止应用程序，并在稍后重新启动重新交付原始意图。这可能会导致看起来像是重复扫描。
- 在 onCreate 中，我检查用户是否仍然有 phone 连接到标签。这证明用户没有将鼠标悬停在带有 ndefTag.connect(); 的标签上
该应用程序似乎运行良好，但在一个特定的 phone（三星 Galaxy Young 2）上，如果用户将 phone 放在标签上几秒钟，NFC 适配器似乎连续开火几次。
发生这种情况时，原始扫描将被取消。这样做的原因是 oncreate 处理标签但是当后续扫描发生时（通过悬停，偶然）， onPause -> onNewIntent 运行。所以 Activity 跳出 onCreate 并停止处理标签。 onNewIntent 显示失败的扫描屏幕并启动菜单屏幕。
以上不是什么大问题，因为用户必须重新扫描标签。
我希望发生的事情是：
当 onCreate 运行时，无论如何处理标签，即使 onNewintent 执行。有没有办法在到达 onNewintent 和 onPause 之前拦截意图？
也许有一个我可以使用的全局标志，可以先检查它以说明 onCreate 仍然是 运行 而 onNewIntent 不应该，或者更重要的是 onPause 没有被调用使 onCreate 停止 运行.
import java.util.List;
import java.util.concurrent.ExecutionException;
import org.ndeftools.Message;
import org.ndeftools.Record;
import android.app.Activity;
import android.app.PendingIntent;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Parcelable;
import android.os.Vibrator;
import android.util.Log;
import android.widget.Toast;
public class NfcActivity extends Activity {
private static final String TAG = NfcActivity.class.getName();
protected NfcAdapter nfcAdapter;
protected PendingIntent nfcPendingIntent;
Handler handler;
Runnable runnable;
Handler failHandler;
Runnable failRunnable;
Parcelable[] messages;
Intent i;
Tag tag;
String tagId;
boolean nfcConnected;
ProgressDialog progressDialog;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.nfcactivitylayout);
Log.e(TAG, "oncreate");
nfcConnected = false;
// initialize NFC
nfcAdapter = NfcAdapter.getDefaultAdapter(this);
nfcPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, this.getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
tag = null;
tagId = null;
i = getIntent();
if ((i.getFlags() & Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY) != 0) {
//check to see if Android has previously killed the app and relaunched it from History
//and delivered the original intent.
//if it has do not process and launch the menu screen
Intent processPayloadIntent = new Intent(NfcActivity.this, NfcscannerActivity.class);
processPayloadIntent.setAction("QRCODE_ACTION");
processPayloadIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(processPayloadIntent);
}else{
tag = i.getParcelableExtra(NfcAdapter.EXTRA_TAG);
tagId = bytesToHexString(tag.getId());
Log.e(TAG, "tagID = " + tagId);
Log.e(TAG, "oncreate intent action = " + i.getAction());
//The activity has captured tag data, prove the user is not hovering over the tag and is doing a good scan
//hovering can trigger the adapter twice
AsyncNfcConnect asnc = new AsyncNfcConnect();
try {
asnc.execute().get();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Log.e(TAG, "nfcConnected!!!!!!!!!!!!!!!!!!!!!!!!! = " + nfcConnected);
if(nfcConnected == true){
int buildVersionSdk = Build.VERSION.SDK_INT;
int buildVersionCodes = Build.VERSION_CODES.GINGERBREAD;
Log.e(TAG, "buildVersionSdk = " + buildVersionSdk
+ "buildVersionCodes = " + buildVersionCodes);
int themeVersion;
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.GINGERBREAD) {
themeVersion = 2;
} else {
themeVersion = 1;
}
try{
progressDialog = new ProgressDialog(this, themeVersion);
progressDialog.setTitle("NFC Tag Scanned");
progressDialog.setMessage("Processing tag...");
progressDialog.setIndeterminate(true);
progressDialog.show();
}catch(Exception e){ }
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(i.getAction()) || NfcAdapter.ACTION_TAG_DISCOVERED.equals(i.getAction())) {
if(NfcScannerApplication.isCanScanNfcTag()){
messages = i.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (messages != null) {
//setContentView(R.layout.successfulnfc);
NfcScannerApplication.startNfcTimer();
//Toast.makeText(this, "NFC timer set", Toast.LENGTH_LONG).show();
Log.e(TAG, "Found " + messages.length + " NDEF messages"); // is almost always just one
vibrate(); // signal found messages :-)
initHandler();
handler.postDelayed(runnable, 2000);
}else{
Toast.makeText(this, "Data on tag was not correct", Toast.LENGTH_LONG).show();
try{
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}else{
try{
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
} else {
Toast.makeText(this, "Tag not recognized correctly", Toast.LENGTH_LONG).show();
try{
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}else{
try{
Toast.makeText(this, "Phone wasn't connected to Tag", Toast.LENGTH_LONG).show();
handler.removeCallbacks(runnable);
Log.e(TAG, "just removed callback to runnable that reads nfc tag data");
}catch(Exception e){
}
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}//end of NFC connect test
}//end of launched from history check
}//end of onCreate
@Override
protected void onStart() {
super.onStart();
Log.e(TAG, "onStart");
}
@Override
protected void onStop() {
super.onStop();
Log.e(TAG, "onStop");
}
@Override
public void onNewIntent(Intent intent) {
Log.e(TAG, "onNewIntent");
Toast.makeText(this, "Bad scan!!!", Toast.LENGTH_LONG).show();
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}//end of onNewIntent
public void enableForegroundMode() {
Log.e(TAG, "enableForegroundMode");
IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED); // filter for all
IntentFilter[] writeTagFilters = new IntentFilter[] {tagDetected};
nfcAdapter.enableForegroundDispatch(this, nfcPendingIntent, writeTagFilters, null);
}
public void disableForegroundMode() {
Log.e(TAG, "disableForegroundMode");
nfcAdapter.disableForegroundDispatch(this);
}
@Override
protected void onResume() {
super.onResume();
Log.e(TAG, "onResume");
enableForegroundMode();
}
@Override
protected void onPause() {
Log.e(TAG, "onPause");
super.onPause();
disableForegroundMode();
if(handler != null){
handler.removeCallbacks(runnable);
}
}
private void vibrate() {
Log.e(TAG, "vibrate");
Vibrator vibe = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE) ;
vibe.vibrate(500);
}
public void initHandler(){
handler = new Handler();
runnable = new Runnable() {
public void run() {
processTag();
}
private void processTag() {
Log.e(TAG, "about to process tag");
try{
progressDialog.dismiss();
}catch(Exception e){
//do nothing
}
// parse to records
for (int i = 0; i < messages.length; i++) {
try {
List<Record> records = new Message((NdefMessage)messages[i]);
Log.e(TAG, "Found " + records.size() + " records in message " + i);
for(int k = 0; k < records.size(); k++) {
Log.e(TAG, " Record #" + k + " is of class " + records.get(k).getClass().getSimpleName());
Record record = records.get(k);
NdefRecord ndefRecord = record.getNdefRecord();
byte[] arr = ndefRecord.getPayload();
String payload = new String(arr);
if(payload.length() > 0){
payload = payload.substring(3, payload.length());
Log.e(TAG, "payload = " + payload);
String[] splitPayload = payload.split(",");
String tagType = splitPayload[0];
String tagCompany = splitPayload[1];
String tagClientID = splitPayload[2];
String tagClientName = splitPayload[3];
if(! tagClientID.equalsIgnoreCase("0") && tagClientID.length() > 0){
handler.post(new Runnable(){
public void run() {
setContentView(R.layout.successfulnfc);
}
});
Intent processPayloadIntent = new Intent(NfcActivity.this, NfcscannerActivity.class);
processPayloadIntent.putExtra("payload", payload);
processPayloadIntent.putExtra("tagid", tagId);
processPayloadIntent.setAction("NFC");
processPayloadIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
//processPayloadIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP|Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(processPayloadIntent);
finish();
overridePendingTransition(0, R.anim.activity_animation_zoom_in);
}else{
Toast.makeText(NfcActivity.this, "Tag data problem/Scan problem.", Toast.LENGTH_LONG).show();
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}else{
Toast.makeText(NfcActivity.this, "Tag data problem/Scan problem.", Toast.LENGTH_LONG).show();
initFailHandler();
failHandler.postDelayed(failRunnable, 1);
}
}
} catch (Exception e) {
Log.e(TAG, "Problem parsing message", e);
}
}
}
};
}
public void initFailHandler(){
failHandler = new Handler();
failRunnable = new Runnable() {
public void run() {
returnToMainMenu();
}
private void returnToMainMenu() {
//Log.e(TAG, "about to return to main menu");
try{
progressDialog.dismiss();
}catch(Exception e){
//do nothing
}
Toast.makeText(NfcActivity.this, "Please check your scanning technique.\nPlease do not hover over tag or swipe...", Toast.LENGTH_LONG).show();
failHandler.post(new Runnable(){
public void run() {
setContentView(R.layout.nfcfail);
}
});
//onBackPressed();
Intent processPayloadIntent = new Intent(NfcActivity.this, NfcscannerActivity.class);
processPayloadIntent.setAction("QRCODE_ACTION");
processPayloadIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(processPayloadIntent);
finish();
//overridePendingTransition(0, R.anim.activity_animation_zoom_in);
}
};
}
private String bytesToHexString(byte[] src) {
StringBuilder stringBuilder = new StringBuilder("0x");
if (src == null || src.length <= 0) {
return null;
}
char[] buffer = new char[2];
for (int i = 0; i < src.length; i++) {
buffer[0] = Character.forDigit((src[i] >>> 4) & 0x0F, 16);
buffer[1] = Character.forDigit(src[i] & 0x0F, 16);
System.out.println(buffer);
stringBuilder.append(buffer);
}
return stringBuilder.toString();
}
private class AsyncNfcConnect extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
NfcActivity.this.nfcConnected = false;
String result;
Ndef ndefTag = Ndef.get(tag);
try {
Log.e(TAG, "about to test connect()********************************************");
ndefTag.connect(); // this should already perform an IO operation and should therefore fail if there is no tag
Log.e(TAG, "Ndef.connect() connected!********************************************");
NdefMessage ndefMsg = ndefTag.getNdefMessage(); // this reads the current NDEF message from the tag and consequently causes an IO operation
NfcActivity.this.nfcConnected = true;
result = "OK";
return result;
} catch (Exception e) {
// there is no tag or communication with tag dropped
Log.e(TAG, "There a problem with connecting to the tag using Ndef.connect(");
NfcActivity.this.nfcConnected = false;
result = "NOTOK";
return result;
} finally {
try {
ndefTag.close();
} catch (Exception e) {
}
}
}
}//end of Async
}
您似乎坚持不在 onNewIntent() 中处理 NFC 意图。我建议 onCreate() 和 onNewIntent() 都调用扫描标签的通用过程。这样，两个入口点将遵循相同的代码路径。
您声称应用程序 "jumps out of onCreate" 可能只是一种修辞手法？发生的情况是您的标签扫描 AsyncNfcConnect 运行s 在单独的线程上作为后台任务（应该如此）。该任务在 onCreate() 中创建，并在 onCreate() 完成后继续 运行ning（您可以在 onCreate() 末尾添加一个 Log 语句来检查） .当与标签的连接以某种方式丢失并重新发现标签时，如您所见，将调用 onNewIntent()。
无论如何都无法阻止这种情况的发生，因此您的应用程序必须能够处理它。要检测并处理它，您可以在 activity 中设置一些标志，以指示您的后台任务正在 运行ning 或有 运行。您还可以存储是否发生异常的信息，并在重新发现时再次尝试扫描标签（这可能需要您实施我上面提出的建议）。如果您想让您的应用程序更加防故障，您还可以存储最后一次扫描标签的 ID，以便在您成功扫描（或未扫描）后重新发现它时再次肯定地识别它。当同一个标签不断出现异常时，您可以在一定次数后向用户指示他（例如，建议将设备放置在不同的位置 w.r.t。标签）。