Android WiFi 电源管理

核心提示：Android 对WiFi电源管理的代码主要在WifiService.java中，如果应用程序想在屏幕被关掉后继续使用WiFi则可以调用acquireWifiLock来锁住WiFi，Android WiFi 电源管理，该操作会阻止WiFi进入睡眠状态，当应用程序不再使用WiFi时需要调用releaseWifiLock来

Android 对WiFi电源管理的代码主要在WifiService.java中。如果应用程序想在屏幕被关掉后继续使用WiFi则可以调用acquireWifiLock来锁住WiFi，该操作会阻止WiFi进入睡眠状态。当应用程序不再使用WiFi时需要调用releaseWifiLock来释放WiFi。之后WiFi可以进入睡眠状态以节省电源。

默认情况下当屏幕被关掉以后，如果没有应用程序在使用WiFi，WiFi会在2分钟后进入睡眠状态。这主要是为防止频繁地改变WiFi的电源模式。

1. INTRODUCTION

WifiLock Allows an application to keep the Wi-Fi radio awake. Normally the Wi-Fi radio may turn off when the user has not used the device in a while. Acquiring a WifiLock will keep the radio on until the lock is released. Multiple applications may hold WifiLocks, and the radio will only be allowed to turn off when no WifiLocks are held in any application.

Before using a WifiLock, consider carefully if your application requires Wi-Fi access, or could function over a mobile network, if available. A program that needs to download large files should hold a WifiLock to ensure that the download will complete, but a program whose network usage is occasional or low-bandwidth should not hold a WifiLock to avoid adversely affecting battery life.

Note that WifiLocks cannot override the user-level "Wi-Fi Enabled" setting, nor Airplane Mode. They simply keep the radio from turning off when Wi-Fi is already on but the device is idle.

2. API

WifiLock APIs are implemented in android.net.wifi.WifiManager.

2.1 acquire()

Locks the Wi-Fi radio on until release is called.

If this WifiLock is reference-counted, each call to acquire will increment the reference count, and the radio will remain locked as long as the reference count is above zero.

If this WifiLock is not reference-counted, the first call to acquire will lock the radio, but subsequent calls will be ignored. Only one call to release will be required, regardless of the number of times that acquire is called.