android - 设备管理 API 示例 : works fine on emulator NoSuchMethod error on Device

Question

我正在尝试制作一个禁用相机的应用程序，我正在尝试 SDK 中的 Device Admin 示例，它在模拟器上运行良好但在设备上，应用程序强制关闭项目点击并显示 NoSuchmethod 错误。

代码 fragment

 public static class AdminSampleFragment extends PreferenceFragment
        implements OnPreferenceChangeListener, OnPreferenceClickListener{

    // Useful instance variables
    protected DeviceAdmin mActivity;
    protected DevicePolicyManager mDPM;
    protected ComponentName mDeviceAdminSample;
    protected boolean mAdminActive;

    // Optional shared UI
    private PreferenceScreen mSetPassword;
    private EditTextPreference mResetPassword;

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        // Retrieve the useful instance variables
        mActivity = (DeviceAdmin) getActivity();
        mDPM = mActivity.mDPM;
        mDeviceAdminSample = mActivity.mDeviceAdminSample;
        mAdminActive = mActivity.isActiveAdmin();

        // Configure the shared UI elements (if they exist)
        mResetPassword = (EditTextPreference) findPreference(KEY_RESET_PASSWORD);
        mSetPassword = (PreferenceScreen) findPreference(KEY_SET_PASSWORD);

        if (mResetPassword != null) {
            mResetPassword.setOnPreferenceChangeListener(this);
        }
        if (mSetPassword != null) {
            mSetPassword.setOnPreferenceClickListener(this);
        }
    }

    @Override
    public void onResume() {
        super.onResume();
        mAdminActive = mActivity.isActiveAdmin();
        reloadSummaries();
        // Resetting the password via API is available only to active admins
        if (mResetPassword != null) {
            mResetPassword.setEnabled(mAdminActive);
        }
    }

    /**
     * Called automatically at every onResume.  Should also call explicitly any time a
     * policy changes that may affect other policy values.
     */
    protected void reloadSummaries() {
        if (mSetPassword != null) {
            if (mAdminActive) {
                // Show password-sufficient status under Set Password button
                boolean sufficient = mDPM.isActivePasswordSufficient();
                mSetPassword.setSummary(sufficient ?
                        R.string.password_sufficient : R.string.password_insufficient);
            } else {
                mSetPassword.setSummary(null);
            }
        }
    }

    @Override
    public boolean onPreferenceClick(Preference preference) {
        if (mSetPassword != null && preference == mSetPassword) {
            Intent intent = new Intent(DevicePolicyManager.ACTION_SET_NEW_PASSWORD);
            startActivity(intent);
            return true;
        }
        return false;
    }

    @Override
    public boolean onPreferenceChange(Preference preference, Object newValue) {
        if (mResetPassword != null && preference == mResetPassword) {
            doResetPassword((String)newValue);
            return true;
        }
        return false;
    }

    /**
     * This is dangerous, so we prevent automated tests from doing it, and we
     * remind the user after we do it.
     */
    private void doResetPassword(String newPassword) {
        if (alertIfMonkey(mActivity, R.string.monkey_reset_password)) {
            return;
        }
        mDPM.resetPassword(newPassword, DevicePolicyManager.RESET_PASSWORD_REQUIRE_ENTRY);
        AlertDialog.Builder builder = new AlertDialog.Builder(mActivity);
        String message = mActivity.getString(R.string.reset_password_warning, newPassword);
        builder.setMessage(message);
        builder.setPositiveButton(R.string.reset_password_ok, null);
        builder.show();
    }

    /**
     * Simple helper for summaries showing local & global (aggregate) policy settings
     */
    protected String localGlobalSummary(Object local, Object global) {
        return getString(R.string.status_local_global, local, global);
    }
}

/**
 * PreferenceFragment for "general" preferences.
 */
public static class GeneralFragment extends AdminSampleFragment
        implements OnPreferenceChangeListener {
    // UI elements
    private CheckBoxPreference mEnableCheckbox;
    private CheckBoxPreference mDisableCameraCheckbox;
    private CheckBoxPreference mDisableKeyguardWidgetsCheckbox;
    private CheckBoxPreference mDisableKeyguardSecureCameraCheckbox;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.device_admin_general);
        mEnableCheckbox = (CheckBoxPreference) findPreference(KEY_ENABLE_ADMIN);
        mEnableCheckbox.setOnPreferenceChangeListener(this);
        mDisableCameraCheckbox = (CheckBoxPreference) findPreference(KEY_DISABLE_CAMERA);
        mDisableCameraCheckbox.setOnPreferenceChangeListener(this);
        mDisableKeyguardWidgetsCheckbox =
            (CheckBoxPreference) findPreference(KEY_DISABLE_KEYGUARD_WIDGETS);
        mDisableKeyguardWidgetsCheckbox.setOnPreferenceChangeListener(this);
        mDisableKeyguardSecureCameraCheckbox =
            (CheckBoxPreference) findPreference(KEY_DISABLE_KEYGUARD_SECURE_CAMERA);
        mDisableKeyguardSecureCameraCheckbox.setOnPreferenceChangeListener(this);
    }

    // At onResume time, reload UI with current values as required
    @Override
    public void onResume() {
        super.onResume();
        mEnableCheckbox.setChecked(mAdminActive);
        enableDeviceCapabilitiesArea(mAdminActive);

        if (mAdminActive) {
            mDPM.setCameraDisabled(mDeviceAdminSample, mDisableCameraCheckbox.isChecked());
            mDPM.setKeyguardDisabledFeatures(mDeviceAdminSample, createKeyguardDisabledFlag());
            reloadSummaries();
        }
    }

    int createKeyguardDisabledFlag() {
        int flags = DevicePolicyManager.KEYGUARD_DISABLE_FEATURES_NONE;
        flags |= mDisableKeyguardWidgetsCheckbox.isChecked() ?
                DevicePolicyManager.KEYGUARD_DISABLE_WIDGETS_ALL : 0;
        flags |= mDisableKeyguardSecureCameraCheckbox.isChecked() ?
                DevicePolicyManager.KEYGUARD_DISABLE_SECURE_CAMERA : 0;
        return flags;
    }

    @Override
    public boolean onPreferenceChange(Preference preference, Object newValue) {
        if (super.onPreferenceChange(preference, newValue)) {
            return true;
        }
        boolean value = (Boolean) newValue;
        if (preference == mEnableCheckbox) {
            if (value != mAdminActive) {
                if (value) {
                    // Launch the activity to have the user enable our admin.
                    Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
                    intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, mDeviceAdminSample);
                    intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,
                            mActivity.getString(R.string.add_admin_extra_app_text));
                    startActivityForResult(intent, REQUEST_CODE_ENABLE_ADMIN);
                    // return false - don't update checkbox until we're really active
                    return false;
                } else {
                    mDPM.removeActiveAdmin(mDeviceAdminSample);
                    enableDeviceCapabilitiesArea(false);
                    mAdminActive = false;
                }
            }
        } else if (preference == mDisableCameraCheckbox) {
            mDPM.setCameraDisabled(mDeviceAdminSample, value);
            reloadSummaries();
        } else if (preference == mDisableKeyguardWidgetsCheckbox
                || preference == mDisableKeyguardSecureCameraCheckbox) {
            mDPM.setKeyguardDisabledFeatures(mDeviceAdminSample, createKeyguardDisabledFlag());
            reloadSummaries();
        }
        return true;
    }

    @Override
    protected void reloadSummaries() {
        super.reloadSummaries();
        String cameraSummary = getString(mDPM.getCameraDisabled(mDeviceAdminSample)
                ? R.string.camera_disabled : R.string.camera_enabled);
        mDisableCameraCheckbox.setSummary(cameraSummary);

        int disabled = mDPM.getKeyguardDisabledFeatures(mDeviceAdminSample);

        String keyguardWidgetSummary = getString(
                (disabled & DevicePolicyManager.KEYGUARD_DISABLE_WIDGETS_ALL) != 0 ?
                        R.string.keyguard_widgets_disabled : R.string.keyguard_widgets_enabled);
        mDisableKeyguardWidgetsCheckbox.setSummary(keyguardWidgetSummary);

        String keyguardSecureCameraSummary = getString(
            (disabled & DevicePolicyManager.KEYGUARD_DISABLE_SECURE_CAMERA) != 0 ?
            R.string.keyguard_secure_camera_disabled : R.string.keyguard_secure_camera_enabled);
        mDisableKeyguardSecureCameraCheckbox.setSummary(keyguardSecureCameraSummary);
    }

    /** Updates the device capabilities area (dis/enabling) as the admin is (de)activated */
    private void enableDeviceCapabilitiesArea(boolean enabled) {
        mDisableCameraCheckbox.setEnabled(enabled);
        mDisableKeyguardWidgetsCheckbox.setEnabled(enabled);
        mDisableKeyguardSecureCameraCheckbox.setEnabled(enabled);
    }
}

日志

05-06 00:19:00.797: E/AndroidRuntime(9614): FATAL EXCEPTION: main


05-06 00:19:00.797: E/AndroidRuntime(9614): java.lang.NoSuchMethodError: android.app.admin.DevicePolicyManager.getKeyguardDisabledFeatures
05-06 00:19:00.797: E/AndroidRuntime(9614):     at com.example.deviceadmin.DeviceAdmin$GeneralFragment.reloadSummaries(DeviceAdmin.java:317)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at com.example.deviceadmin.DeviceAdmin$AdminSampleFragment.onResume(DeviceAdmin.java:159)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at com.example.deviceadmin.DeviceAdmin$GeneralFragment.onResume(DeviceAdmin.java:256)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:877)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1036)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1018)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.FragmentManagerImpl.dispatchResume(FragmentManager.java:1810)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.Activity.performResume(Activity.java:4549)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2461)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2499)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1997)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.ActivityThread.access$600(ActivityThread.java:127)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.os.Looper.loop(Looper.java:137)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at android.app.ActivityThread.main(ActivityThread.java:4448)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at java.lang.reflect.Method.invokeNative(Native Method)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at java.lang.reflect.Method.invoke(Method.java:511)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
05-06 00:19:00.797: E/AndroidRuntime(9614):     at dalvik.system.NativeStart.main(Native Method)

请帮忙。 !我的问题很长一段时间都没有得到满意的答案:(

提前致谢

Answer 1

虽然前面添加了一些Device Admin API，但是具体方法getKeyguardDisabledFeatures()仅在 API 17 中添加，即 android Android 4.2 或 JELLY_BEAN_MR1 以及撰写本文时发布的最新版本。

因此，您将无法在您的 ICS 测试设备上使用该方法，或在 2013 年 5 月用户手中的许多设备上使用该方法。

大概您的成功测试是在运行 4.2 或 4.2.2 的模拟器上进行的