Android(安卓)6.0 权限申请源码解析

这篇文章主要从调用流程上分析一下Android 6.0 权限检查和申请

权限管理涉及到四个基本API：

检查是否有权限
checkSelfPermission(String)
是否需要提示用户为什么需要这个权限
shouldShowRequestPermissionRationale (String permission)
请求权限:
requestPermissions (String[] permissions, int requestCode)
处理回调
onRequestPermissionsResult(int, String[], int[])
请求permission后系统调用该函数，通知app permission是被允许还是拒绝。

权限检查

权限检查使用的核心API就是checkSelfPermission, 接下来我们从这个API开始分析权限检查
/frameworks/support/compat/java/android/support/v4/content/ContextCompat.java

public static int checkSelfPermission(@NonNull Context context, @NonNull String permission) {    if (permission == null) {        throw new IllegalArgumentException("permission is null");    }    return context.checkPermission(permission,     android.os.Process.myPid(), Process.myUid());}

从上面代码看出在检查权限的时候必须保证permission不能为空,否则就会抛出异常, 接着调用ContextImpl的checkPermission方法,

`/frameworks/base/core/java/android/app/ContextImpl.java

public int checkPermission(String permission, int pid, int uid, IBinder callerToken) {    if (permission == null) {        throw new IllegalArgumentException("permission is null");    }    try {        return ActivityManager.getService().checkPermissionWithToken(                            permission, pid, uid, callerToken);    } catch (RemoteException e) {        throw e.rethrowFromSystemServer();    }}

/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

public int checkPermissionWithToken(String permission, int pid, int uid, IBinder callerToken) {    if (permission == null) {        return PackageManager.PERMISSION_DENIED;    }    // We might be performing an operation on behalf of an indirect binder    // invocation, e.g. via {@link #openContentUri}.  Check and adjust the    // client identity accordingly before proceeding.    Identity tlsIdentity = sCallerIdentity.get();    if (tlsIdentity != null && tlsIdentity.token == callerToken) {        Slog.d(TAG, "checkComponentPermission() adjusting {pid,uid} to {"+ tlsIdentity.pid + "," + tlsIdentity.uid + "}");        uid = tlsIdentity.uid;        pid = tlsIdentity.pid;    }    return checkComponentPermission(permission, pid, uid, -1, true);}

int checkComponentPermission(String permission, int pid, int uid,            int owningUid, boolean exported) {    if (pid == MY_PID) {        return PackageManager.PERMISSION_GRANTED;    }    return ActivityManager.checkComponentPermission(permission, uid,            owningUid, exported);}

/frameworks/base/core/java/android/app/ActivityManager.java

public static int checkComponentPermission(String permission, int uid, int owningUid, boolean exported) {    // Root, system server get to do everything.    final int appId = UserHandle.getAppId(uid);    if (appId == Process.ROOT_UID || appId == Process.SYSTEM_UID) {        return PackageManager.PERMISSION_GRANTED;    }    // Isolated processes don't get any permissions.    if (UserHandle.isIsolated(uid)) {        return PackageManager.PERMISSION_DENIED;    }    // If there is a uid that owns whatever is being accessed, it has    // blanket access to it regardless of the permissions it requires.    if (owningUid >= 0 && UserHandle.isSameApp(uid, owningUid)) {        return PackageManager.PERMISSION_GRANTED;    }    // If the target is not exported, then nobody else can get to it.    if (!exported) {        /*        RuntimeException here = new RuntimeException("here");        here.fillInStackTrace();        Slog.w(TAG, "Permission denied: checkComponentPermission() owningUid=" + owningUid,                here);        */        return PackageManager.PERMISSION_DENIED;    }    if (permission == null) {        return PackageManager.PERMISSION_GRANTED;    }    try {        return AppGlobals.getPackageManager()                .checkUidPermission(permission, uid);    } catch (RemoteException e) {        throw e.rethrowFromSystemServer();    }}

/frameworks/base/core/java/android/app/AppGlobals.java

public static IPackageManager getPackageManager() {    return ActivityThread.getPackageManager();}

/frameworks/base/core/java/android/app/ActivityThread.java

public static IPackageManager getPackageManager() {    if (sPackageManager != null) {        //Slog.v("PackageManager", "returning cur default = " + sPackageManager);        return sPackageManager;    }    IBinder b = ServiceManager.getService("package");    //Slog.v("PackageManager", "default service binder = " + b);    sPackageManager = IPackageManager.Stub.asInterface(b);    //Slog.v("PackageManager", "default service = " + sPackageManager);    return sPackageManager;}

/frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public int checkUidPermission(String permName, int uid) {    final int callingUid = Binder.getCallingUid();    final int callingUserId = UserHandle.getUserId(callingUid);    final boolean isCallerInstantApp = getInstantAppPackageName(callingUid) != null;    final boolean isUidInstantApp = getInstantAppPackageName(uid) != null;    final int userId = UserHandle.getUserId(uid);    if (!sUserManager.exists(userId)) {        return PackageManager.PERMISSION_DENIED;    }    synchronized (mPackages) {        Object obj = mSettings.getUserIdLPr(UserHandle.getAppId(uid));        if (obj != null) {            if (obj instanceof SharedUserSetting) {                if (isCallerInstantApp) {                    return PackageManager.PERMISSION_DENIED;                }            } else if (obj instanceof PackageSetting) {                final PackageSetting ps = (PackageSetting) obj;                if (filterAppAccessLPr(ps, callingUid, callingUserId)) {                    return PackageManager.PERMISSION_DENIED;                }            }            final SettingBase settingBase = (SettingBase) obj;            final PermissionsState permissionsState = settingBase.getPermissionsState();            if (permissionsState.hasPermission(permName, userId)) {                if (isUidInstantApp) {                    BasePermission bp = mSettings.mPermissions.get(permName);                    if (bp != null && bp.isInstant()) {                        return PackageManager.PERMISSION_GRANTED;                    }                } else {                    return PackageManager.PERMISSION_GRANTED;                }            }            // Special case: ACCESS_FINE_LOCATION permission includes ACCESS_COARSE_LOCATION            if (Manifest.permission.ACCESS_COARSE_LOCATION.equals(permName) && permissionsState                        .hasPermission(Manifest.permission.ACCESS_FINE_LOCATION, userId)) {               return PackageManager.PERMISSION_GRANTED;            }        } else {            ArraySet perms = mSystemPermissions.get(uid);            if (perms != null) {                if (perms.contains(permName)) {                   return PackageManager.PERMISSION_GRANTED;                }                if (Manifest.permission.ACCESS_COARSE_LOCATION.equals(permName) && perms                            .contains(Manifest.permission.ACCESS_FINE_LOCATION)) {                    return PackageManager.PERMISSION_GRANTED;                    }            }        }    }    return PackageManager.PERMISSION_DENIED;}

/frameworks/base/core/java/android/content/pm/PackageManager.java

public Intent buildRequestPermissionsIntent(@NonNull String[] permissions) {        if (ArrayUtils.isEmpty(permissions)) {            throw new IllegalArgumentException("permission cannot be null or empty");        }        Intent intent = new Intent(ACTION_REQUEST_PERMISSIONS);        intent.putExtra(EXTRA_REQUEST_PERMISSIONS_NAMES, permissions);        intent.setPackage(getPermissionControllerPackageName());        return intent;}

请求权限

GrantPermissionsActivity

<activity android:name=".permission.ui.GrantPermissionsActivity"    android:configChanges="orientation|keyboardHidden|screenSize"    android:excludeFromRecents="true"    android:theme="@style/GrantPermissions"    android:visibleToInstantApps="true">    <intent-filter android:priority="1">        <action android:name="android.content.pm.action.REQUEST_PERMISSIONS" />        <category android:name="android.intent.category.DEFAULT" />    intent-filter>activity>

/frameworks/base/core/java/android/app/Activity.java

public final void requestPermissions(@NonNull String[] permissions, int requestCode) {    if (requestCode < 0) {        throw new IllegalArgumentException("requestCode should be >= 0");    }    if (mHasCurrentPermissionsRequest) {        Log.w(TAG, "Can reqeust only one set of permissions at a time");        // Dispatch the callback with empty arrays which means a cancellation.        onRequestPermissionsResult(requestCode, new String[0], new int[0]);        return;    }    Intent intent = getPackageManager().buildRequestPermissionsIntent(permissions);    startActivityForResult(REQUEST_PERMISSIONS_WHO_PREFIX, intent, requestCode, null);    mHasCurrentPermissionsRequest = true;}

/frameworks/base/core/java/android/content/pm/PackageManager.java

public Intent buildRequestPermissionsIntent(@NonNull String[] permissions) {    if (ArrayUtils.isEmpty(permissions)) {        throw new IllegalArgumentException("permission cannot be null or empty");    }    Intent intent = new Intent(ACTION_REQUEST_PERMISSIONS);    intent.putExtra(EXTRA_REQUEST_PERMISSIONS_NAMES, permissions);                  intent.setPackage(getPermissionControllerPackageName());    return intent;}

权限管理涉及到四个基本API：

权限检查

请求权限

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