android 默认打开高精度定位模式，accept Improve location accuracy

需求：GPS位置信息模式默认为“仅限设备”， 应客户的要求，默认为“高精确度”
修改：/frameworks/base/packages/SettingsProvider/res/values/defaults.xml

- <string name="def_location_providers_allowed" translatable="false">gps</string>
+ <string name="def_location_providers_allowed" translatable="false">gps,network</string>

编译后烧录，发现没变化还是默认仅限设备(我的项目中有gms)，追踪源码发现在SettingsHelper.java中被限制了。
源码路径：frameworks/base/packages/SettingsProvider/src/com/android/providers/settings/SettingsHelper.java

  ...
} else if (Settings.Secure.LOCATION_PROVIDERS_ALLOWED.equals(name)) {
           setGpsLocation(value);
           return;
} 
  ...
private void setGpsLocation(String value) {
    UserManager um = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
    if (um.hasUserRestriction(UserManager.DISALLOW_SHARE_LOCATION)) {
        return;
    }
    final String GPS = LocationManager.GPS_PROVIDER;
    
    boolean enabled =
            GPS.equals(value) ||
            value.startsWith(GPS + ",") ||
            value.endsWith("," + GPS) ||
            value.contains("," + GPS + ",");
    Settings.Secure.setLocationProviderEnabled(
              mContext.getContentResolver(), GPS, enabled);
}

可以看到，如果def_location_providers_allowed的值包含gps，就还是默认仅限设备，如果只设置为network，就默认关闭gps了。直接设置

final String NETWORK = LocationManager.NETWORK_PROVIDER;
Settings.Secure.setLocationProviderEnabled(
              mContext.getContentResolver(), NETWORK, enabled);

会有google的弹窗提示，不符合我们的要求。

分析如何去掉Improve location accuracy弹窗

1.使用adb命令抓取弹窗所在的activity,得到com.google.android.location.network.ConfirmAlertActivity
2.根据activity名字，搜索log得到关键词content://com.google.settings/partner/network_location_opt_in
3.反编译GmsCore_arm.apk，从GmsCore_arm的源码中知道点击同意之后对network_location_opt_in的值做了操作，然后关闭弹窗。
adb查看activity
apktool反编译

下面给出完整修改：

1.去掉Improve location accuracy弹窗，设置location provider

修改：/package/apps/Launcher3/src/com/android/launcher3/launcher.java

// 在onCreate()方法中添加
mHandler.postDelayed(new Runnable() {
       public void run() {
       	    // 判断用户是否手动设置了定位模式
			int mode = Settings.System.getInt(getContentResolver(), "location_mode_changed", 0); // 1 : has changed  0 : no change
			// 去掉Improve location accuracy弹窗
			ContentResolver localContentResolver = getContentResolver();
			ContentValues localContentValues = new ContentValues();
			localContentValues.put("name", "network_location_opt_in");
			localContentValues.put("value", 1);  
			localContentResolver.insert(Uri.parse("content://com.google.settings/partner"), localContentValues);
				
			if(mode == 0){ // user did not choose the location mode
			   Settings.Secure.setLocationProviderEnabled(localContentResolver, "network", true);
			}	
       }
}, 10000);   // 这里加延时是由于google的应用服务起来比较慢，起来之后会设置network_location_opt_in的值

2.添加google应用中自定义的权限,不加会报错

修改：/package/apps/Launcher3/AndroidManifest.xml

<uses-permission android:name="com.google.android.providers.settings.permission.WRITE_GSETTINGS" />

3.系统签名，不是系统签名会报错

修改：/package/apps/Launcher3/Android.mk

LOCAL_CERTIFICATE := platform

4.用户手动设置定位模式

修改：/package/apps/Settings/src/com/android/settings/location/LocationMode.java

 @Override
 public void onRadioButtonClicked(RadioButtonPreference emiter) {
      int mode = Settings.Secure.LOCATION_MODE_OFF;
      if (emiter == mHighAccuracy) {
          mode = Settings.Secure.LOCATION_MODE_HIGH_ACCURACY;
      } else if (emiter == mBatterySaving) {
          mode = Settings.Secure.LOCATION_MODE_BATTERY_SAVING;
      } else if (emiter == mSensorsOnly) {
          mode = Settings.Secure.LOCATION_MODE_SENSORS_ONLY;
      }
      
+     Settings.System.putInt(getContentResolver(), "location_mode_changed", 1); // 1 : has changed  0 : no change
      setLocationMode(mode);
    }

可以在studio中编写，然后对apk做系统签名验证。
对apk系统签名.