我正在尝试创建一个可以更改设备密码的 Android 应用程序。我读到了 Device Administration Application 我尝试运行 this sample，这是我的主要 Activity 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();
        }
    });
}

我得到了这个错误:

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)

谁能帮我解决一下？

最佳答案

引用 the documentation that you linked to :

One of the major events a device admin application has to handle is the user enabling the application. The user must explicitly enable the application for the policies to be enforced. If the user chooses not to enable the application it will still be present on the device, but its policies will not be enforced, and the user will not get any of the application's benefits.

正如 Harvey 先生所指出的，该错误消息意味着用户尚未将您的应用启用为设备管理员。

进一步引用文档:

The process of enabling the application begins when the user performs an action that triggers the ACTION_ADD_DEVICE_ADMIN intent.

Here is a sample project演示设置设备管理员。 关键在 LockMeNowActivity 中:

/***
  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，当用户单击触发 lockMeNow() 的按钮时，我会检查我的应用程序是否是设备管理员，如果不是，我会引导用户到设置中的正确位置应用决定是否让我的应用成为设备管理员。

关于java - 如何以编程方式更改密码？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25512426/