需求：不需要用户点击允许按钮直接获取READ_PHONE_STATE等权限
分析：因为用户可以在手机中通过打开设置-应用-选择具体应用-权限界面，手动打开用户所需要的权限（界面效果如图），我就想我怎么样可以在代码中模拟点击按钮打开权限的操作，于是我就去查看源码。
第一步：通过adb shell dumpsys activity | grep "mFocusedActivity"命令，我们可以发现当前页面是com.android.packageinstaller/.permission.ui.ManagePermissionsActivity,于是我就去google下载了packagerinstaller的apk，找到了ManagePermissionActivity的源码，然后发现activity中添加的是AppPermissionsFragment
//AppPermissionsFragment源码
@Override
public boolean onPreferenceChange(final Preference preference, Object newValue) {
String groupName = preference.getKey();
final AppPermissionGroup group = mAppPermissions.getPermissionGroup(groupName);
if (group == null) {
return false;
}
addToggledGroup(group);
if (LocationUtils.isLocationGroupAndProvider(group.getName(), group.getApp().packageName)) {
LocationUtils.showLocationDialog(getContext(), mAppPermissions.getAppLabel());
return false;
}
if (newValue == Boolean.TRUE) {
group.grantRuntimePermissions(false);
} else {
final boolean grantedByDefault = group.hasGrantedByDefaultPermission();
if (grantedByDefault || (!group.hasRuntimePermission() && !mHasConfirmedRevoke)) {
new AlertDialog.Builder(getContext())
.setMessage(grantedByDefault ? R.string.system_warning
: R.string.old_sdk_deny_warning)
.setNegativeButton(R.string.cancel, null)
.setPositiveButton(R.string.grant_dialog_button_deny_anyway,
new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
((SwitchPreference) preference).setChecked(false);
group.revokeRuntimePermissions(false);
if (!grantedByDefault) {
mHasConfirmedRevoke = true;
}
}
})
.show();
return false;
} else {
group.revokeRuntimePermissions(false);
}
}
return true;
}
第二步：通过查看AppPermissionsFragment源码，我们发现调用的是group.grantRuntimePermissions(false)和 group.revokeRuntimePermissions(false)，group是AppPermissionGroup，发现在AppPermissionGroup最后调用的就是PackageManager的grantRuntimePermission（(以grantRuntimePermissions分析)）。
//AppPermissionGroup源码
public boolean grantRuntimePermissions(boolean fixedByTheUser, String[] filterPermissions) {
final int uid = mPackageInfo.applicationInfo.uid;
// We toggle permissions only to apps that support runtime
// permissions, otherwise we toggle the app op corresponding
// to the permission if the permission is granted to the app.
for (Permission permission : mPermissions.values()) {
if (filterPermissions != null
&& !ArrayUtils.contains(filterPermissions, permission.getName())) {
continue;
}
if (mAppSupportsRuntimePermissions) {
// Do not touch permissions fixed by the system.
if (permission.isSystemFixed()) {
return false;
}
// Ensure the permission app op enabled before the permission grant.
if (permission.hasAppOp() && !permission.isAppOpAllowed()) {
permission.setAppOpAllowed(true);
mAppOps.setUidMode(permission.getAppOp(), uid, AppOpsManager.MODE_ALLOWED);
}
// Grant the permission if needed.
if (!permission.isGranted()) {
permission.setGranted(true);
mPackageManager.grantRuntimePermission(mPackageInfo.packageName,
permission.getName(), mUserHandle);
}
// Update the permission flags.
if (!fixedByTheUser) {
// Now the apps can ask for the permission as the user
// no longer has it fixed in a denied state.
if (permission.isUserFixed() || permission.isUserSet()) {
permission.setUserFixed(false);
permission.setUserSet(false);
mPackageManager.updatePermissionFlags(permission.getName(),
mPackageInfo.packageName,
PackageManager.FLAG_PERMISSION_USER_FIXED
| PackageManager.FLAG_PERMISSION_USER_SET,
0, mUserHandle);
}
}
} else {
// Legacy apps cannot have a not granted permission but just in case.
if (!permission.isGranted()) {
continue;
}
int killUid = -1;
int mask = 0;
// If the permissions has no corresponding app op, then it is a
// third-party one and we do not offer toggling of such permissions.
if (permission.hasAppOp()) {
if (!permission.isAppOpAllowed()) {
permission.setAppOpAllowed(true);
// Enable the app op.
mAppOps.setUidMode(permission.getAppOp(), uid, AppOpsManager.MODE_ALLOWED);
// Legacy apps do not know that they have to retry access to a
// resource due to changes in runtime permissions (app ops in this
// case). Therefore, we restart them on app op change, so they
// can pick up the change.
killUid = uid;
}
// Mark that the permission should not be be granted on upgrade
// when the app begins supporting runtime permissions.
if (permission.shouldRevokeOnUpgrade()) {
permission.setRevokeOnUpgrade(false);
mask |= PackageManager.FLAG_PERMISSION_REVOKE_ON_UPGRADE;
}
}
if (mask != 0) {
mPackageManager.updatePermissionFlags(permission.getName(),
mPackageInfo.packageName, mask, 0, mUserHandle);
}
if (killUid != -1) {
mActivityManager.killUid(uid, KILL_REASON_APP_OP_CHANGE);
}
}
}
return true;
}
第三步：android 7上查看PackageManager源码
@SystemApi
public abstract void grantRuntimePermission(@NonNull String packageName,
@NonNull String permissionName, @NonNull UserHandle user);
@SystemApi
public abstract void revokeRuntimePermission(@NonNull String packageName,
@NonNull String permissionName, @NonNull UserHandle user);
第四步：通过源码我们可以看到PM中的grant和revoke方法都是系统方法。调用grant和revoke需要系统权限，调用方法如下：
if (para != null) {
try {
String pkg = para.getString(KEY_PKG_NAME);
String permissionName = para.getString(PERMISSION_NAME);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
PackageManager packageManager = mContext.getPackageManager();
Method method = packageManager.getClass().getDeclaredMethod("grantRuntimePermission", String.class, String.class, UserHandle.class);
method.setAccessible(true);
method.invoke(packageManager, pkg, permissionName, Process.myUserHandle());
} else {
LogUtils.e(TAG, "android os version is too low");
}
} catch (Exception e) {
LogUtils.e(TAG, "error when SERVICE_EXTENDED_API_SET_NOTICICATION_OBSERVIER");
e.printStackTrace();
}
}
注意：在grantRuntimePermission的时候，permissionName传值如果是Manifest.permission.READ_PHONE_STATE是可以的，但是revokeRuntimePermission的时候permissionName必须是android.permission.READ_PHONE_STATE，当执行revokeRuntimePermission的时候，被回收权限的应用会直接退出，如log所示03-30 06:57:46.585 1418-2509/system_process I/ActivityManager: Killing 4179:com.xxxxxxx.xxxxxxxx/u0a102 (adj 0): permissions revoked