本文主要是介绍Android：控制按键灯亮灭【button-backlight】，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java
1.导包
import java.io.DataOutputStream;
import java.io.FileOutputStream;
Handler mHandler3;
2.新建handler对象
public void init(Context context, IWindowManager windowManager,
WindowManagerFuncs windowManagerFuncs) {
mHandler3 = new Handler();
3.延时处理方法
public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {
// Basic policy based on interactive state.
int result;
boolean isWakeKey = (policyFlags & WindowManagerPolicy.FLAG_WAKE) != 0
|| event.isWakeKey();
//*/ 20210513. for backlight control
if(interactive) {
writeFile("/sys/class/leds/button-backlight/brightness", "1");
mHandler3.removeMessages(0);
mHandler3.postDelayed(new Runnable() {
public void run() {
writeFile("/sys/class/leds/button-backlight/brightness", "0");
}
}, 5 * 1000);
}
//*/
if (interactive || (isInjected && !isWakeKey)) {
// When the device is interactive or the key is injected pass the
// key to the application.
result = ACTION_PASS_TO_USER;
isWakeKey = false;
if (interactive) {
// If the screen is awake, but the button pressed was the one that woke the device
// then don't pass it to the application
if (keyCode == mPendingWakeKey && !down) {
result = 0;
}
// Reset the pending key
mPendingWakeKey = PENDING_KEY_NULL;
}
} else if (!interactive && shouldDispatchInputWhenNonInteractive(event)) {
// If we're currently dozing with the screen on and the keyguard showing, pass the key
// to the application but preserve its wake key status to make sure we still move
// from dozing to fully interactive if we would normally go from off to fully
// interactive.
result = ACTION_PASS_TO_USER;
// Since we're dispatching the input, reset the pending key
mPendingWakeKey = PENDING_KEY_NULL;
} else {
// When the screen is off and the key is not injected, determine whether
// to wake the device but don't pass the key to the application.
result = 0;
if (isWakeKey && (!down || !isWakeKeyWhenScreenOff(keyCode))) {
isWakeKey = false;
}
// Cache the wake key on down event so we can also avoid sending the up event to the app
if (isWakeKey && down) {
mPendingWakeKey = keyCode;
}
}
4.屏灭时写0
@Override
public void screenTurningOff(ScreenOffListener screenOffListener) {
mWindowManagerFuncs.screenTurningOff(screenOffListener);
synchronized (mLock) {
if (mKeyguardDelegate != null) {
mKeyguardDelegate.onScreenTurningOff();
}
}
//*/ 20231017 for backlight control
writeFile("/sys/class/leds/button-backlight/brightness", "0");
//*/
}
5.写节点方法
//*/
private void writeFile(String filePath, String line) {
File a = new File(filePath);
if (a.exists()) {
try {
FileOutputStream fs = new FileOutputStream(a);
DataOutputStream ds = new DataOutputStream(fs);
ds.write(line.getBytes());
ds.flush();
ds.close();
fs.close();
} catch (Exception ex) {
Log.e(TAG, "writeFile() Exception: " + filePath);
}
} else {
Log.d(TAG, "writeFile() File not exist: " + filePath);
try {
if (a.createNewFile()) {
Log.d(TAG, "writeFile() File created: " + filePath);
try {
FileOutputStream fs = new FileOutputStream(a);
DataOutputStream ds = new DataOutputStream(fs);
ds.write(line.getBytes());
ds.flush();
ds.close();
fs.close();
} catch (Exception ex) {
Log.e(TAG, "writeFile() Exception: " + filePath);
}
} else {
Log.d(TAG, "writeFile() Create file fail: " + filePath);
}
} catch (IOException e) {
Log.e(TAG, "writeFile() creatFile Exception: " + filePath);
}
}
}
//*/
最后别忘了底层的支持 ：
defconfig / debug_defconfig文件
CONFIG_BUTTON_BACKLIGHT_SUPPORT_GPIO=y
按键灯的权限问题：两个RC文件
1，/device/mediatek/mt67xx/init.mt6761.rc
on boot 下：
chmod 0664 /sys/class/leds/button-backlight/brightness
chown system system /sys/class/leds/button-backlight/brightness
2,/device/droi/项目名/init.project.rc
on post-fs-data下：
# button light
chmod 0666 sys/class/leds/button-backlight/brightness
chown system system sys/class/leds/button-backlight/brightness
其实其他什么状态灯、扫码灯皆如此，只是节点名称不同。
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