总结:即使获取了wifi锁,当手机使用电池运行时,wifi也会在一段时间后断开。
我已将问题简化为带有启动线程的按钮的单个活动。它只是向 PC 上运行的回显服务器发送 100.000 个字符串(每 100 毫秒一个字符串)。请参阅下面的代码。我可以使用 WireShark 查看流量,并且回显服务器也显示字符串。请注意在开始发送之前如何获取 WiFi 和电源锁(当然,以及之后如何释放)。
然而,当手机使用电池运行并且用户关闭手机时,它会持续发送字符串一段时间,然后 WiFi 会断开,手机甚至不会响应 ping。需要600到6000秒才能断开连接(数字是那一轮,所以我认为它们很重要)。
连接空调时它可以完美工作,所以我猜它在某种程度上与电源管理有关。
为了测试它,我只需启动该活动,启动 echo 服务器,启动 WireShark,按“开始”按钮(android:onClick="doStart"
),挡住手机并将其放在桌子上。我去吃午饭或其他什么地方,600-6000 秒后,我可以看到 WireShark 上的 tx 错误,echo 服务器已停止接收流量,并且手机不响应 ping。
手机是2.2,WiFi策略设置为“15m后睡眠”。
package Odroid.test;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Date;
import android.app.Activity;
import android.content.Context;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.os.PowerManager;
import android.view.View;
import android.widget.Button;
public class Test extends Activity {
PowerManager _powerManagement = null;
PowerManager.WakeLock _wakeLock = null;
WifiManager.WifiLock _wifiLock = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void doStart(View v) {
DoerThreadFake t = new DoerThreadFake();
t.start();
}
private class DoerThreadFake extends Thread {
public void run() {
runOnUiThread(new Runnable() {
public void run() {
((Button) findViewById(R.id.start)).setText("Doing...");
}
});
_keepOnStart();
Socket s;
byte[] buffer = new byte[1000];
try {
s = new Socket("192.168.0.16", 2000);
PrintStream ps = new PrintStream(s.getOutputStream());
InputStream is = s.getInputStream();
for (int i = 0; i < 100000; i++) {
ps.println(System.currentTimeMillis() +"("+(new Date()).toString() +") : " + i);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
while (is.available() > 0) {
int a = is.available();
if (a > 1000) a = 1000;
is.read(buffer, 0, a); // Clean echo
}
}
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
_keepOnStop();
runOnUiThread(new Runnable() {
public void run() {
((Button) findViewById(R.id.start)).setText("Done");
}
});
}
private void _keepOnStart() {
if (_powerManagement == null) {
_powerManagement = (PowerManager) getSystemService(Context.POWER_SERVICE);
}
if (_wakeLock == null) {
_wakeLock = _powerManagement.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP | PowerManager.ON_AFTER_RELEASE,
"0 Backup power lock");
}
_wakeLock.acquire();
WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
if (wifiManager != null) {
_wifiLock = wifiManager.createWifiLock("0 Backup wifi lock");
_wifiLock.acquire();
}
}
private void _keepOnStop() {
if ((_wifiLock != null) && (_wifiLock.isHeld())) {
_wifiLock.release();
}
if ((_wakeLock != null) && (_wakeLock.isHeld())) {
_wakeLock.release();
}
}
}
}
清单:
<?xml version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="Odroid.test"
android:versionCode="1"
android:versionName="1.0"
>
<uses-sdk android:minSdkVersion="4" />
<application
android:icon="@drawable/icon"
android:label="@string/app_name"
>
<activity
android:name=".Test"
android:label="@string/app_name"
>
<intent-filter>
<action
android:name="android.intent.action.MAIN" />
<category
android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
</manifest>
任何想法?