[英]why onReceive() is being called many times?
我不知道為什么當我連接或斷開wifi時,wifi接收器下面發布的代碼中的相應回調至少被多次調用了三次,並且
因此,如果我想基於當前的wifi狀態調用一個函數,該函數將被調用很多次,而我不希望這樣的行為,尤其是在
有wifi連接時應調用的功能,我正在顯示一個對話框,並且由於該回調將被調用多次,該對話框將被調用多次,因此會導致重疊。
請在下面發布的logcat上進行操作,這只是我得到的示例。
請讓我知道為什么wifi狀態對應的回調多次被調用,如何避免這種多次調用?
代碼 :
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
tv_status = (TextView) findViewById(R.id.tv_status);
this.registerReceiver(this.myWifiReceiver, new IntentFilter(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION));
}
private BroadcastReceiver myWifiReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Log.d(TAG, "@onReceive()");
mConnMgr = (ConnectivityManager)getSystemService(network_service);
WifiManager wifiMgr = (WifiManager) context.getSystemService(WiFi_Service);
switch (wifiMgr.getWifiState()) {
case WifiManager.WIFI_STATE_ENABLED:
Log.d(TAG, "wifi enabled");
if (mConnMgr != null) {
networkInfo = mConnMgr.getActiveNetworkInfo();
if (networkInfo != null) {
switch(networkInfo.getType()) {
case ConnectivityManager.TYPE_WIFI:
if (networkInfo.isConnected()) {
tv_status.setText("Connected");
Log.d(TAG, "Connected");
}else if (networkInfo.isConnectedOrConnecting()) {
tv_status.setText("Status: CONNECTED Or CONNECTING");
Log.d(TAG, "Status: CONNECTED Or CONNECTING");
}else if (networkInfo.isFailover()){
Log.d(TAG, "Status: FailOver");
}else if (networkInfo.isRoaming()) {
Log.d(TAG, "Status: Roaming");
}else if (networkInfo.isAvailable()) {
Log.d(TAG, "Status: Available");
} else {
Log.d(TAG, "Status: disconnected");
}
break;
}
}else {
tv_status.setText("Status: No Default NetWork Connected");
Log.d(TAG, "Status: No Default NetWork Connected");
}
} else {
tv_status.setText("Status: ConnMgr is null");
Log.d(TAG, "Status: ConnMgr is null");
}
break;
LogCat :
03-04 15:31:31.031: D/MainActivity(16120): @onReceive()
03-04 15:31:31.031: D/MainActivity(16120): wifi enabled
03-04 15:31:31.032: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:31:31.546: D/MainActivity(16120): @onReceive()
03-04 15:31:31.547: D/MainActivity(16120): wifi enabled
03-04 15:31:31.547: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:31:31.617: D/MainActivity(16120): @onReceive()
03-04 15:31:31.618: D/MainActivity(16120): wifi enabled
03-04 15:31:31.620: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:31:31.636: D/MainActivity(16120): @onReceive()
03-04 15:31:31.636: D/MainActivity(16120): wifi enabled
03-04 15:31:31.637: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:32:28.661: D/MainActivity(16120): @onReceive()
03-04 15:32:28.663: D/MainActivity(16120): wifi enabled
03-04 15:32:28.666: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:32:28.708: D/MainActivity(16120): @onReceive()
03-04 15:32:28.709: D/MainActivity(16120): wifi enabled
03-04 15:32:28.710: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:32:28.722: D/MainActivity(16120): @onReceive()
03-04 15:32:28.722: D/MainActivity(16120): wifi enabled
03-04 15:32:28.722: D/MainActivity(16120): Status: No Default NetWork Connected
Update_1 :
使用計時器的MySolution :
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
tv_status = (TextView) findViewById(R.id.tv_status);
IntentFilter intfil = new IntentFilter(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION);
this.registerReceiver(this.myWifiReceiver, intfil);
}
private BroadcastReceiver myWifiReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Log.d(TAG, "@onReceive()");
Timer t1 = new Timer();
Timer t2 = new Timer();
if (!locked) {
if (scheduled1) {
t1.cancel();
t1.purge();
}
if (scheduled2) {
t2.cancel();
t2.purge();
}
WifiManager wifiMgr = (WifiManager) context.getSystemService(WiFi_Service);
switch (wifiMgr.getWifiState()) {
case WifiManager.WIFI_STATE_ENABLED:
Log.d(TAG, "wifi enabled");
locked = true;
t1 = new Timer();
t1.schedule(MQTTReceiverLockTimedTask, 4000);
scheduled1 = true;
module();
break;
case WifiManager.WIFI_STATE_DISABLED:
Log.d(TAG, "wifi disabled");
locked = true;
t2 = new Timer();
t2.schedule(MQTTReceiverLockTimedTask, 4000);
scheduled2 = true;
break;
}
}
}
};
TimerTask MQTTReceiverLockTimedTask = new TimerTask() {
@Override
public void run() {
// TODO Auto-generated method stub
locked = false;
}
};
protected void module() {
// TODO Auto-generated method stub
mConnMgr = (ConnectivityManager)getSystemService(network_service);
if (mConnMgr != null) {
networkInfo = mConnMgr.getActiveNetworkInfo();
if (networkInfo != null) {
switch(networkInfo.getType()) {
case ConnectivityManager.TYPE_WIFI:
if (networkInfo.isConnected()) {
tv_status.setText("Connected");
Log.d(TAG, "Connected");
}else if (networkInfo.isConnectedOrConnecting()) {
tv_status.setText("Status: CONNECTED Or CONNECTING");
Log.d(TAG, "Status: CONNECTED Or CONNECTING");
}else if (networkInfo.isFailover()){
Log.d(TAG, "Status: FailOver");
}else if (networkInfo.isRoaming()) {
Log.d(TAG, "Status: Roaming");
}else if (networkInfo.isAvailable()) {
Log.d(TAG, "Status: Available");
} else {
Log.d(TAG, "Status: disconnected");
}
break;
}
}else {
tv_status.setText("Status: No Default NetWork Connected");
Log.d(TAG, "Status: No Default NetWork Connected");
}
} else {
tv_status.setText("Status: ConnMgr is null");
Log.d(TAG, "Status: ConnMgr is null");
}
}
從WifiManager文檔上WifiManager.SUPPLICANT_STATE_CHANGED_ACTION
:
廣播意圖動作,指示與接入點建立連接的狀態已更改。另外一個提供了新的SupplicantState。
由於SupplicantState
提供了有關建立連接狀態的更詳細的信息,因此您會收到許多對onReceive()
調用。 每次此狀態更改時,都會廣播一個新的意圖。 由於您只需要較少的詳細信息,因此看來您獲得了許多相同的廣播。
關於如何避免這種情況的方法:搜索另一種收聽意圖,例如ConnectivityManager.CONNECTIVITY_ACTION
如果它滿足您的需要),或嘗試Mahmoud Elmorabea的解決方案-將當前的wifi連接狀態保存在Activity類以及onReceive()
,檢查連接狀態是否已更改。 如果還沒有,請跳過其余代碼。 否則,請運行代碼並更新您的狀態。 如果使用此解決方案,請記住在“活動”生命周期中保存“狀態”字段。
將WiFi的當前狀態保存在某個地方,某個管理器或其他某個位置,並且僅當以與當前狀態不同的狀態調用onReceive()時才執行代碼。
假設您在活動中使用此代碼。
在您的活動中,您將擁有一個稱為currentWifiState的屬性,起初它等於-100; 例如
在您的接收器中,代碼如下所示
if (wifiManager.getWifiState() == currentWifiState)
return;
然后,如果您要通知的狀態與當前狀態相同,則您將不執行任何操作。
除非Wifi狀態更改,否則您的代碼將不會執行。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.