在实现锁屏功能时能可能会出现这个问题出现…..这主要是因为锁屏需要管理员的权限…….

解决方法如下:

1、新建一个MyAdmin.java

package com.njupt.testrotate1;

import android.app.admin.DeviceAdminReceiver;

public class MyAdmin extends DeviceAdminReceiver {

}

2、在清单文件中如下配置:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.njupt.testrotate1"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="8" />

    <uses-permission android:name="android.permission.VIBRATE"/>
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.njupt.testrotate1.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        
        <receiver android:name="com.njupt.testrotate1.MyAdmin" >
            <meta-data android:name="android.app.device_admin"
                android:resource="@xml/my_admin"/>
            <intent-filter >
                <action android:name="android.app.action.DEVICE_ADMIN_ENABLED"/>
            </intent-filter>
        </receiver>
    </application>

</manifest>

3、在res目录下新建xml/my_admin.xml

<?xml version="1.0" encoding="utf-8"?>
<device-admin xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- 
    limit-password  设置密码的规则
    watch-login 监控屏幕解锁尝试次数
    reset-password 更改屏幕解锁密码
    force-lock 设备自动锁屏
    wipe-data 删除全部的数据
    
     -->
    <uses-policies>
        <limit-password/>
        <watch-login />
        <reset-password />
        <force-lock />
        <wipe-data />
    </uses-policies>
</device-admin>

4、在MainAcitivity中如下书写:

private DevicePolicyManager devicePolicyManager;
	private boolean isAdminActive;

devicePolicyManager = (DevicePolicyManager) getSystemService(Context.DEVICE_POLICY_SERVICE);
		// 申请权限
		ComponentName componentName = new ComponentName(this, MyAdmin.class);
		// 判断该组件是否有系统管理员的权限
		isAdminActive = devicePolicyManager
				.isAdminActive(componentName);
		
		if(!isAdminActive){//这一句一定要有...
			Intent intent = new Intent();
			//指定动作
			intent.setAction(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
			//指定给那个组件授权
			intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, componentName);
			startActivity(intent);
		}

if(isAdminActive){
					Toast.makeText(this, "具有权限,将进行锁屏....", 1).show();
					devicePolicyManager.lockNow();
					devicePolicyManager.resetPassword("123321", 0);
				}

MainAcitivity的完整代码如下：

package com.njupt.testrotate1;

import android.os.Bundle;
import android.os.Vibrator;
import android.app.Activity;
import android.app.Service;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements SensorEventListener {

	private Button clear;
	private TextView tv1;
	private SensorManager mSensorManager;
	private Vibrator vibrator;
	private int counter = 1;
	private DevicePolicyManager devicePolicyManager;
	private boolean isAdminActive;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
		vibrator = (Vibrator) getSystemService(Service.VIBRATOR_SERVICE);
		// clear = (Button) findViewById(R.id.clear);

		// clear.setOnClickListener(new Button.OnClickListener() {
		//
		// @Override
		// public void onClick(View v) {
		// clear.setText("现在给button赋值喽....");
		// }
		// });
		//
		tv1 = (TextView) findViewById(R.id.tv1);

		devicePolicyManager = (DevicePolicyManager) getSystemService(Context.DEVICE_POLICY_SERVICE);
		// 申请权限
		ComponentName componentName = new ComponentName(this, MyAdmin.class);
		// 判断该组件是否有系统管理员的权限
		isAdminActive = devicePolicyManager
				.isAdminActive(componentName);
		
		if(!isAdminActive){
			Intent intent = new Intent();
			//指定动作
			intent.setAction(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
			//指定给那个组件授权
			intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, componentName);
			startActivity(intent);
		}

	}

	@Override
	protected void onResume() {
		super.onResume();

		mSensorManager.registerListener(this,
				mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
				SensorManager.SENSOR_DELAY_GAME);
	}

	@Override
	protected void onStop() {
		mSensorManager.unregisterListener(this);
		super.onStop();
	}

	@Override
	protected void onPause() {
		mSensorManager.unregisterListener(this);
		super.onPause();
	}

	@Override
	public void onAccuracyChanged(Sensor sensor, int accuracy) {

	}

	@Override
	public void onSensorChanged(SensorEvent event) {
		int sensorType = event.sensor.getType();
		float[] values = event.values;

		float x = values[0];
		float y = values[1];

		if (sensorType == Sensor.TYPE_ACCELEROMETER) {
			tv1.setText("现在的x轴是: " + x + " y轴是: " + y);

			if (Math.abs(x) > 9.0 || Math.abs(y) > 9.0) {
//				Toast.makeText(this, "现在的垂直方向已经超过了90度,将进行锁屏", 1).show();
				vibrator.vibrate(500);

				System.out.println("...............isAdminActive: "
						+ isAdminActive);
				if(isAdminActive){
					Toast.makeText(this, "具有权限,将进行锁屏....", 1).show();
					devicePolicyManager.lockNow();
					devicePolicyManager.resetPassword("123321", 0);
				}
				

			}
		}
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}