我设法制作了一个 NFC 应用程序，当扫描特定标签时，手机将自动与一个特定的 Wi-Fi 建立连接。（即使 Wi-Fi 已关闭）我已经在代码（标签）中包含了 SSID 和密码，因此用户只需扫描标签即可连接。但是，我注意到在我第一次点击时，Wi-Fi 已启用（如果禁用）但它不会连接到 Wi-Fi。只有在第二次点击时，它才会连接到指定的 Wi-Fi。为什么会这样？
我的代码：
@Override
protected void onNewIntent(Intent intent) {
String result2="";
String resultid="";
String resultpw="";
super.onNewIntent(intent);
SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);
int storedPreference = preferences.getInt("storedInt", 0);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
NdefMessage[] messages = null;
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs != null) {
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i < rawMsgs.length; i++) {
messages[i] = (NdefMessage) rawMsgs[i];
}
}
if(messages[0] != null) {
/*
String result="";
byte[] payload = messages[0].getRecords()[0].getPayload();
// this assumes that we get back am SOH followed by host/code
for (int b = 0; b<payload.length; b++) { // skip SOH
result += (char) payload[b];
}
*/
try{
//grabbing 2nd payload
byte[] payload2 = messages[0].getRecords()[1].getPayload();
for (int test = 0; test<payload2.length; test++) { // skip SOH
result2 += (char) payload2[test];
//Toast.makeText(this,result2,Toast.LENGTH_SHORT).show();
}
}
catch(ArrayIndexOutOfBoundsException e){
Toast.makeText(getApplicationContext(), "Wrong tag detected. Try again!", Toast.LENGTH_SHORT).show();
}
//grab ssid
try{
byte[] payload3 = messages[0].getRecords()[2].getPayload();
for (int test = 0; test<payload3.length; test++) { // skip SOH
resultid += (char) payload3[test];
//Toast.makeText(this,result2,Toast.LENGTH_SHORT).show();
}
}
catch(ArrayIndexOutOfBoundsException e){
}
//grab ssid_pw
try{
byte[] payload4 = messages[0].getRecords()[3].getPayload();
for (int test = 0; test<payload4.length; test++) { // skip SOH
resultpw += (char) payload4[test];
//Toast.makeText(this,result2,Toast.LENGTH_SHORT).show();
}
}
catch(ArrayIndexOutOfBoundsException e){
}
if (result2.contains("StarbucksBestCoffee"))
{
final ImageView img = (ImageView)findViewById(R.id.imageView1);
/* Call to convert bytes to hex .
*
String uid = toHex(intent.getByteArrayExtra(NfcAdapter.EXTRA_ID));
Toast.makeText(this, uid, Toast.LENGTH_LONG).show();*/
/*if (storedPreference!=10)
{
Toast.makeText(getApplicationContext(), "Coupon collected!", Toast.LENGTH_SHORT).show();
storedPreference++;
SharedPreferences.Editor editor = preferences.edit();
editor.putInt("storedInt", storedPreference);
img.setImageResource(images[storedPreference]);
img.invalidate();
}*/
if (storedPreference==10)
{
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setCancelable(false);
builder.setTitle("Redeem Your Coupon?");
builder.setInverseBackgroundForced(true);
builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which)
{
dialog.dismiss();
SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putInt("storedInt", 0); // value to store
editor.commit();
img.setImageResource(images[0]);
img.invalidate();
}
});
builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
img.setImageResource(images[10]);
img.invalidate();
}
});
builder.show();
}
else
{
Toast.makeText(getApplicationContext(), "Coupon collected!", Toast.LENGTH_SHORT).show();
storedPreference++;
SharedPreferences.Editor editor = preferences.edit();
editor.putInt("storedInt", storedPreference);
editor.commit();
img.setImageResource(images[storedPreference]);
img.invalidate();
}
if (resultid!=null&&resultpw!=null)
{
//Wi-Fi Manager auto-connect
WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
WifiConfiguration wc = new WifiConfiguration();
wc.SSID = "\"" + resultid + "\"";
wc.preSharedKey = "\"" + resultpw + "\"";
wc.hiddenSSID = true;
wc.status = WifiConfiguration.Status.ENABLED;
wc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.TKIP);
wc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.CCMP);
wc.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK);
wc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP);
wc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP);
wc.allowedProtocols.set(WifiConfiguration.Protocol.RSN);
int res = wifi.addNetwork(wc);
Log.d("WifiPreference", "add Network returned " + res );
boolean b = wifi.enableNetwork(res, true);
Log.d("WifiPreference", "enableNetwork returned " + b );
wifi.setWifiEnabled(true);
}
}
else
{
Toast.makeText(getApplicationContext(), "Wrong tag detected!", Toast.LENGTH_SHORT).show();
}