android 一键锁屏实例源码，android4.2测试通过

【核心代码】

package com.xhcbird.lock;

import android.os.Bundle;
import android.app.Activity;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;

public class MainActivity extends Activity {
	private DevicePolicyManager mDevicePolicyManager;
	private ComponentName mComponentName;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// setContentView(R.layout.activity_main);
		//传说中的Log.i
		Log.i("--->lock!!", "start lock");
		mDevicePolicyManager = (DevicePolicyManager) getSystemService(Context.DEVICE_POLICY_SERVICE);
		mComponentName = new ComponentName(this, LockReceiver.class);
		// 判断是否有权限
		if (mDevicePolicyManager.isAdminActive(mComponentName)) {
			mDevicePolicyManager.lockNow();
			// 下面两行都不好使，在android4.2上
			// android.os.Process.killProcess(android.os.Process.myPid());
			// System.exit(0);
			finish();
		} else {
			activeManager();
		}
	}

	private void activeManager() {
		// 激活设备管理器获取权限
		Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
		intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, mComponentName);
		intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION, "传说中的一键锁屏");
		startActivity(intent);
		finish();
	}

	@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;
	}

}