如何以编程方式更改密码？

Question

我正在尝试创建一个可以更改设备密码的Android应用程序.我阅读了有关设备管理应用程序的信息, 我尝试运行此示例,这是我的主要活动代码:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    final Activity context = this;
    final String new_pass = ((EditText)findViewById(R.id.editext)).getText().toString();
    ((Button)findViewById(R.id.button)).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            DevicePolicyManager devicePolicyManager =
                    (DevicePolicyManager)context.getSystemService(context.DEVICE_POLICY_SERVICE);
            ComponentName demoDeviceAdmin = new ComponentName(context, MainActivity.class);

            devicePolicyManager.setPasswordQuality(
                    demoDeviceAdmin,DevicePolicyManager.PASSWORD_QUALITY_UNSPECIFIED);
            devicePolicyManager.setPasswordMinimumLength(demoDeviceAdmin, 5);

            boolean result = devicePolicyManager.resetPassword("123456",
                    DevicePolicyManager.RESET_PASSWORD_REQUIRE_ENTRY);

            Toast.makeText(context,
                    "button_lock_password_device..."+result,
                    Toast.LENGTH_LONG).show();
        }
    });
}

我收到了这个错误:

08-26 22:36:51.280  15249-15249/co.rishe.secretpolice.app E/AndroidRuntime? FATAL EXCEPTION: main
java.lang.SecurityException: No active admin ComponentInfo{com.example.secretpolice.app/com.example.secretpolice.app.MainActivity}
        at android.os.Parcel.readException(Parcel.java:1425)
        at android.os.Parcel.readException(Parcel.java:1379)
        at android.app.admin.IDevicePolicyManager$Stub$Proxy.setPasswordQuality(IDevicePolicyManager.java:1359)
        at android.app.admin.DevicePolicyManager.setPasswordQuality(DevicePolicyManager.java:323)
        at co.rishe.secretpolice.app.MainActivity$1.onClick(MainActivity.java:32)
        at android.view.View.performClick(View.java:4211)
        at android.view.View$PerformClick.run(View.java:17267)
        at android.os.Handler.handleCallback(Handler.java:615)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4898)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
        at dalvik.system.NativeStart.main(Native Method)

任何人都可以帮助我如何解决它？

Answer 1

引用您链接到的文档:

设备管理应用程序必须处理的主要事件之一是启用应用程序的用户.用户必须明确启用应用程序以强制执行策略.如果用户选择不启用该应用程序,它仍将出现在设备上,但其策略将不会被强制执行,并且用户将无法获得任何应用程序的任何好处.

正如Harvey先生指出的那样,错误消息表示用户尚未启用您的应用程序作为设备管理员.

进一步引用文档:

当用户执行触发ACTION_ADD_DEVICE_ADMIN意图的操作时,启动应用程序的过程开始.

这是一个示例项目,演示如何设置设备管理员.关键在于LockMeNowActivity:

/***
  Copyright (c) 2012 CommonsWare, LLC
  Licensed under the Apache License, Version 2.0 (the "License"); you may not
  use this file except in compliance with the License. You may obtain a copy
  of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
  by applicable law or agreed to in writing, software distributed under the
  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  OF ANY KIND, either express or implied. See the License for the specific
  language governing permissions and limitations under the License.

  From _The Busy Coder's Guide to Android Development_
    http://commonsware.com/Android
 */

package com.commonsware.android.lockme;

import android.app.Activity;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;

public class LockMeNowActivity extends Activity {
  private DevicePolicyManager mgr=null;
  private ComponentName cn=null;

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

    setContentView(R.layout.main);
    cn=new ComponentName(this, AdminReceiver.class);
    mgr=(DevicePolicyManager)getSystemService(DEVICE_POLICY_SERVICE);
  }

  public void lockMeNow(View v) {
    if (mgr.isAdminActive(cn)) {
      mgr.lockNow();
    }
    else {
      Intent intent=
          new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
      intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, cn);
      intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,
                      getString(R.string.device_admin_explanation));
      startActivity(intent);
    }
  }
}

在这里,当用户点击触发的按钮时lockMeNow(),我会检查我的应用是否是设备管理员,如果不是,我会引导用户到设置应用中的正确位置来决定是否让我的应用成为设备管理员.