android 4.4之后非默认的短信应用已经没有办法删除短信了。像以前那样用如下方法是不会没法删除短信的（即使在xml中配置了短信的读写权限），同时也不会有报错或其他提示。
public void deleteSMS() {
try {
ContentResolver CR = getContentResolver();
// Query SMS
Uri uriSms = Uri.parse("content://sms/inbox");
Cursor c = CR.query(uriSms, new String[] { "_id", "thread_id" },
null, null, null);
if (null != c && c.moveToFirst()) {
do {
// Delete SMS
long threadId = c.getLong(1);
int result = CR.delete(Uri
.parse("content://sms/conversations/" + threadId),
null, null);
Log.d("deleteSMS", "threadId:: " + threadId + " result::"
+ result);
} while (c.moveToNext());
}
} catch (Exception e) {
Log.d("deleteSMS", "Exception:: " + e);
}
}
但通过打印可以看到上述代码的result是等于0的，即没有删除掉短信。
这个是因为在：/frameworks/base/services/java/com/android/server/AppOpsService.java中android系统添加了权限检查的函数
检查用户设定权限的函数是：checkOperation() 和 noteOperation()，区别是 checkOperation() 只是检查 Operation 的情况，noteOperation() 还会记录访问时间等信息，代码如下：
@Override
public int checkOperation(int code, int uid, String packageName) {
verifyIncomingUid(uid);
verifyIncomingOp(code);
synchronized (this) {
Op op = getOpLocked(AppOpsManager.opToSwitch(code), uid, packageName, false);
if (op == null) {
return AppOpsManager.MODE_ALLOWED;
}
return op.mode;
}
}
@Override
public int noteOperation(int code, int uid, String packageName) {
verifyIncomingUid(uid);
verifyIncomingOp(code);
synchronized (this) {
Ops ops = getOpsLocked(uid, packageName, true);
if (ops == null) {
if (DEBUG) Log.d(TAG, "noteOperation: no op for code " + code + " uid " + uid
+ " package " + packageName);
return AppOpsManager.MODE_IGNORED;
}
Op op = getOpLocked(ops, code, true);
if (op.duration == -1) {
Slog.w(TAG, "Noting op not finished: uid " + uid + " pkg " + packageName
+ " code " + code + " time=" + op.time + " duration=" + op.duration);
}
op.duration = 0;
final int switchCode = AppOpsManager.opToSwitch(code);
final Op switchOp = switchCode != code ? getOpLocked(ops, switchCode, true) : op;
if (switchOp.mode != AppOpsManager.MODE_ALLOWED) {
if (DEBUG) Log.d(TAG, "noteOperation: reject #" + op.mode + " for code "
+ switchCode + " (" + code + ") uid " + uid + " package " + packageName);
op.rejectTime = System.currentTimeMillis();
return switchOp.mode;
}
if (DEBUG) Log.d(TAG, "noteOperation: allowing code " + code + " uid " + uid
+ " package " + packageName);
op.time = System.currentTimeMillis();
op.rejectTime = 0;
return AppOpsManager.MODE_ALLOWED;
}
}
然后在ContentProvider可以找到如下代码就是对应用删除短信的权限进行检查
@Override
public int delete(String callingPkg, Uri uri, String selection, String[] selectionArgs) {
validateIncomingUri(uri);
uri = getUriWithoutUserId(uri);
if (enforceWritePermission(callingPkg, uri) != AppOpsManager.MODE_ALLOWED) {
return 0;
}
final String original = setCallingPackage(callingPkg);
try {
return ContentProvider.this.delete(uri, selection, selectionArgs);
} finally {
setCallingPackage(original);
}
}
private int enforceWritePermission(String callingPkg, Uri uri) throws SecurityException {
enforceWritePermissionInner(uri);
if (mWriteOp != AppOpsManager.OP_NONE) {
return mAppOpsManager.noteOp(mWriteOp, Binder.getCallingUid(), callingPkg);
}
return AppOpsManager.MODE_ALLOWED;
}
不过幸运的是在AppOpsService.java中也提供了修改权限的接口：修改某个 App 的某项权限的函数是 setMode()，其中就是修改成员变量 mUidOps。mUidOps 是一个List 保存了某个package对应的所有权限的mode (允许，忽略)，具体代码如下：
@Override
public void setMode(int code, int uid, String packageName, int mode) {
verifyIncomingUid(uid);
verifyIncomingOp(code);
ArrayList<Callback> repCbs = null;
code = AppOpsManager.opToSwitch(code);
synchronized (this) {
Op op = getOpLocked(code, uid, packageName, true);
if (op != null) {
if (op.mode != mode) {
op.mode = mode;
ArrayList<Callback> cbs = mOpModeWatchers.get(code);
if (cbs != null) {
if (repCbs == null) {
repCbs = new ArrayList<Callback>();
}
repCbs.addAll(cbs);
}
cbs = mPackageModeWatchers.get(packageName);
if (cbs != null) {
if (repCbs == null) {
repCbs = new ArrayList<Callback>();
}
repCbs.addAll(cbs);
}
if (mode == AppOpsManager.MODE_ALLOWED) {
// If going into the default mode, prune this op
// if there is nothing else interesting in it.
if (op.time == 0 && op.rejectTime == 0) {
Ops ops = getOpsLocked(uid, packageName, false);
if (ops != null) {
ops.remove(op.op);
if (ops.size() <= 0) {
HashMap<String, Ops> pkgOps = mUidOps.get(uid);
if (pkgOps != null) {
pkgOps.remove(ops.packageName);
if (pkgOps.size() <= 0) {
mUidOps.remove(uid);
}
}
}
}
}
}
scheduleWriteNowLocked();
}
}
}
if (repCbs != null) {
for (int i=0; i<repCbs.size(); i++) {
try {
repCbs.get(i).mCallback.opChanged(code, packageName);
} catch (RemoteException e) {
}
}
}
}
AppOpsManager 是一个管理类来和 AppOpsService 通信，两者关联起来的代码如下：
/**
* Common implementation of Context API, which provides the base
* context object for Activity and other application components.
*/
class ContextImpl extends Context {
registerService(APP_OPS_SERVICE, new ServiceFetcher() {
public Object createService(ContextImpl ctx) {
IBinder b = ServiceManager.getService(APP_OPS_SERVICE);
IAppOpsService service = IAppOpsService.Stub.asInterface(b);
return new AppOpsManager(ctx, service);
}});
.....
}
他的函数实现比较简单，重点是把控制转移到 AppOpsService 就可以了。例如 noteOperation() 和 setMode() 在 AppOpsManager 里面调用他们的函数是 noteOp() 和 setMode()，代码如下：
public int noteOp(int op, int uid, String packageName) {
try {
int mode = mService.noteOperation(op, uid, packageName);
if (mode == MODE_ERRORED) {
throw new SecurityException("Operation not allowed");
}
return mode;
} catch (RemoteException e) {
}
return MODE_IGNORED;
}
public void setMode(int code, int uid, String packageName, int mode) {
try {
mService.setMode(code, uid, packageName, mode);
} catch (RemoteException e) {
}
}
OK，到这里我们应该就能有解决方法了，虽然接口没有公开，但我们在apk中利用反射来调用AppOpsManager，再利用setMode方法来给自己的应用打开权限，代码如下：
复制代码
public final class SmsWriteOpUtil {
private static final int OP_WRITE_SMS = 15;
public static boolean isWriteEnabled(Context context) {
int uid = getUid(context);
Object opRes = checkOp(context, OP_WRITE_SMS, uid);
if (opRes instanceof Integer) {
return (Integer) opRes == AppOpsManager.MODE_ALLOWED;
}
return false;
}
public static boolean setWriteEnabled(Context context, boolean enabled) {
int uid = getUid(context);
int mode = enabled ? AppOpsManager.MODE_ALLOWED
: AppOpsManager.MODE_IGNORED;
return setMode(context, OP_WRITE_SMS, uid, mode);
}
private static Object checkOp(Context context, int code, int uid) {
AppOpsManager appOpsManager = (AppOpsManager) context
.getSystemService(Context.APP_OPS_SERVICE);
Class appOpsManagerClass = appOpsManager.getClass();
try {
Class[] types = new Class[3];
types[0] = Integer.TYPE;
types[1] = Integer.TYPE;
types[2] = String.class;
Method checkOpMethod = appOpsManagerClass.getMethod("checkOp",
types);
Object[] args = new Object[3];
args[0] = Integer.valueOf(code);
args[1] = Integer.valueOf(uid);
args[2] = context.getPackageName();
Object result = checkOpMethod.invoke(appOpsManager, args);
return result;
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return null;
}
private static boolean setMode(Context context, int code, int uid, int mode) {
AppOpsManager appOpsManager = (AppOpsManager) context
.getSystemService(Context.APP_OPS_SERVICE);
Class appOpsManagerClass = appOpsManager.getClass();
try {
Class[] types = new Class[4];
types[0] = Integer.TYPE;
types[1] = Integer.TYPE;
types[2] = String.class;
types[3] = Integer.TYPE;
Method setModeMethod = appOpsManagerClass.getMethod("setMode",
types);
Object[] args = new Object[4];
args[0] = Integer.valueOf(code);
args[1] = Integer.valueOf(uid);
args[2] = context.getPackageName();
args[3] = Integer.valueOf(mode);
setModeMethod.invoke(appOpsManager, args);
return true;
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return false;
}
private static int getUid(Context context) {
try {
int uid = context.getPackageManager().getApplicationInfo(
context.getPackageName(), PackageManager.GET_SERVICES).uid;
return uid;
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
return 0;
}
}
}
使用起起来也很方便：
if (!SmsWriteOpUtil.isWriteEnabled(getApplicationContext())) {
SmsWriteOpUtil.setWriteEnabled(
getApplicationContext(), true);
}
deleteSMS();
......
注意还别忘：
<uses-permission android:name="android.permission.READ_SMS" />
<uses-permission android:name="android.permission.WRITE_SMS" />
