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我有一个运行 Android 的嵌入式模块，并且操作系统在大约 5 分钟不活动后断开 WiFi。如果我随后运行任何使用网络连接的应用程序，WiFi 将保持关闭状态，并且图标不会显示在状态栏中。我必须进入设置和 WiFi 设置才能恢复 WiFi。

我有一个应用程序必须通过 WiFi 连接定期发送数据。如果我在 WiFi 处于活动状态的情况下启动程序并每 2-3 分钟发送一次数据，WiFi 将保持活动状态并且永远不会断开连接。如果我让 WiFi 断开连接然后尝试发送，它永远不会恢复。在代码中，调用：

    wifi.isWifiEnabled()

始终返回 true，但图标仍然隐藏，表示 WiFi 未连接。我试图从代码中调用 reconnect() 作为带有按钮的测试，但 WiFi 从未出现。

从终端调试端口，我可以键入 IFCONFIG WLAN0 UP 并且 WiFi 连接到 AP。

我可以拨打任何电话会导致 WiFi 重新连接吗？除了检测 TCP/IP 连接失败之外，我有什么方法可以实际检测到 WiFi 已断开连接？

为了响应下面的请求，我添加了以下代码片段和 LOGCAT 输出

    wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);

    wifiLock = wifi.createWifiLock(WifiManager.WIFI_MODE_FULL, "Mini210-Lock");
    if(!wifiLock.isHeld())
    {
        wifi.setWifiEnabled(true);
        wifi.reconnect();
        // wifi.reassociate(); // Also try this!!
        wifiLock.acquire();    // Keep system alive
        Log.i("Alarm System", "WiFi Lock Acquired");
    }

运行上述代码时，Logcat 显示如下。

    09-10 22:43:25.273: I/Alarm System(611): WiFi Lock Acquired
    09-10 22:43:25.417: I/ActivityManager(91): Display axon.alarm.system/.AlarmSystemActivity: +15s198ms (total +4h23m59s645ms)
    09-10 22:43:31.636: W/wpa_supplicant(133): Failed to initiate AP scan.
    09-10 22:43:41.636: W/wpa_supplicant(133): Failed to initiate AP scan.

当我在调试监控端口输入ifconfig wlan0 up时，logcat中出现如下（部分重复输出已被删除）

    09-10 22:56:12.726: I/wpa_supplicant(133): CTRL-EVENT-SCAN-RESULTS  Ready
    09-10 22:56:12.726: I/wpa_supplicant(133): Trying to associate with 00:22:75:32:a9:47 (SSID='kpk_mobile' freq=2412 MHz)
    09-10 22:56:20.976: D/dhcpcd(623): checking 192.168.1.123 is available on attached networks
    09-10 22:56:20.976: D/dhcpcd(623): sending ARP probe (1 of 3), next in 1.73 seconds
    09-10 22:56:22.710: D/dhcpcd(623): sending ARP probe (2 of 3), next in 1.00 seconds
    09-10 22:56:23.714: D/dhcpcd(623): sending ARP probe (3 of 3), next in 2.00 seconds
    09-10 22:56:25.718: D/dhcpcd(623): leased 192.168.1.123 for 86400 seconds
    09-10 22:56:25.718: D/dhcpcd(623): adding IP address 192.168.1.123/24
    09-10 22:56:25.718: D/dhcpcd(623): adding route to 0.0.0.0/0 via 192.168.1.1
    09-10 22:56:25.730: D/dhcpcd(623): executing `/system/etc/dhcpcd/dhcpcd-run-hooks', reason BOUND
    09-10 22:56:25.773: D/dhcpcd(623): forking to background
    09-10 22:56:25.804: V/WifiStateTracker(91): DhcpHandler: DHCP request succeeded
    09-10 22:56:25.804: V/WifiStateTracker(91): IP configuration: ipaddr 192.168.1.123  gateway 192.168.1.1 netmask 255.255.255.0 dns1 192.168.1.1 dns2 0.0.0.0 DHCP server 192.168.1.1 lease 86400 seconds
    09-10 22:56:25.816: I/TelephonyRegistry(91): notifyDataConnection: state=0 isDataConnectivityPossible=false reason=dataDisabled interfaceName=null networkType=0
    09-10 22:56:25.828: D/WifiWatchdogService(91): (android.server.ServerThread) kpk_mobile (00:22:75:32:a9:47) does not require the watchdog
    09-10 22:56:25.843: V/FTPDroid(356): EventsReceiver: NETWORK_STATE_CHANGED_ACTION (exists: true, connected: true)
    09-10 22:56:25.863: D/Tethering(91): MasterInitialState.processMessage what=3
    09-10 22:56:25.902: I/GTalkService(278): [ServiceAutoStarter] --- connectivity changed
    09-10 22:56:25.902: I/GTalkService(278): [ServiceAutoStarter] --- start GTalk   service ---
    09-10 22:56:27.789: D/dhcpcd(647): sending ARP announce (1 of 2), next in 2.00 seconds
    09-10 22:56:29.789: D/dhcpcd(647): sending ARP announce (2 of 2)
    09-10 22:56:29.789: D/dhcpcd(647): renew in 43196 seconds
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2 回答 2

1 
WifiManager wifiManager = (WifiManager) this.getApplicationContext()
                .getSystemService(Context.WIFI_SERVICE);
wifiManager.setWifiEnabled(true);

试试这个，不知道行不行。

于 2012-09-10T02:59:53.463 回答
0

在清单中使用此权限

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.UPDATE_DEVICE_STATS"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>

使用以下命令将其状态设置为 ON：

wifiManager = (WifiManager) this.getSystemService(Context.WIFI_SERVICE); 
wifiManager.setWifiEnabled(true);
于 2012-09-10T03:57:36.187 回答