android 5.0 以上获取栈顶应用包名以及程序锁的实现

在这里我们只考虑5.0以上的系统，首先我们需要5.0的sdK，并且要申请权限，代码如下：

private String getTaskPackname() {  
        String currentApp = "CurrentNULL";  
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {  
            UsageStatsManager usm = (UsageStatsManager) this.getSystemService("usagestats");  
            long time = System.currentTimeMillis();  
            List appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time);  
            if (appList != null && appList.size() > 0) {  
                SortedMap mySortedMap = new TreeMap();  
                for (UsageStats usageStats : appList) {  
                    mySortedMap.put(usageStats.getLastTimeUsed(), usageStats);  
                }  
                if (mySortedMap != null && !mySortedMap.isEmpty()) {  
                    currentApp = mySortedMap.get(mySortedMap.lastKey()).getPackageName();  
                }  
            }  
        } else {  
            ActivityManager am = (ActivityManager) this.getSystemService(Context.ACTIVITY_SERVICE);  
            List tasks = am.getRunningAppProcesses();  
            currentApp = tasks.get(0).processName;  
        }  
        Log.e("TAG", "Current App in foreground is: " + currentApp);  
        return currentApp;  
    }

如果没有申请权限，返回null，所以要加上

Intent intent = new Intent(  
                        Settings.ACTION_USAGE_ACCESS_SETTINGS);  
                startActivity(intent);  

进到设置页面，加上这个权限。这样就能拿到包名。下面附上监控某些应用，若在前台，跳出禁止使用demo。代码如下：

package com.example.lockdemo;

import java.util.List;
import java.util.SortedMap;
import java.util.TreeMap;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.ActivityManager;
import android.app.usage.UsageStats;
import android.app.usage.UsageStatsManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.provider.Settings;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;


public class MainActivity extends ActionBarActivity {

	
	private Button button ;
	
	
	Handler  handler = new Handler()
	{
		public void handleMessage(android.os.Message msg) 
		{
			
			//getTaskPackname();
			if("com.sina.weibo".equals(getTaskPackname())) 
			{
				startActivity(new Intent(MainActivity.this,LockActivity.class));
			}

			handler.sendEmptyMessageDelayed(1, 500);
			
		};
	};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button)findViewById(R.id.button);
        handler.sendEmptyMessageDelayed(1, 500);
       //isNoSwitch();
       
        button.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				
				Intent intent = new Intent(  
                        Settings.ACTION_USAGE_ACCESS_SETTINGS);  
                startActivity(intent);  
			}
		});
      

       
    }


   

    
  
    @TargetApi(Build.VERSION_CODES.CUPCAKE) @SuppressLint("NewApi") private String getTaskPackname() {  
        String currentApp = "CurrentNULL";  
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {  
            UsageStatsManager usm = (UsageStatsManager) this.getSystemService("usagestats");  
            long time = System.currentTimeMillis();  
            List appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time);  
            if (appList != null && appList.size() > 0) {  
                SortedMap mySortedMap = new TreeMap();  
                for (UsageStats usageStats : appList) {  
                    mySortedMap.put(usageStats.getLastTimeUsed(), usageStats);  
                }  
                if (mySortedMap != null && !mySortedMap.isEmpty()) {  
                    currentApp = mySortedMap.get(mySortedMap.lastKey()).getPackageName();  
                }  
            }  
        } else {  
            ActivityManager am = (ActivityManager) this.getSystemService(Context.ACTIVITY_SERVICE);  
            List tasks = am.getRunningAppProcesses();  
            currentApp = tasks.get(0).processName;  
        }  
        Log.e("TAG", "Current App in foreground is: " + currentApp);  
        return currentApp;  
    }
    
    private boolean isNoOption() {  
        PackageManager packageManager = getApplicationContext()  
                .getPackageManager();  
        Intent intent = new Intent(Settings.ACTION_USAGE_ACCESS_SETTINGS);  
        List list = packageManager.queryIntentActivities(intent,  
                PackageManager.MATCH_DEFAULT_ONLY);  
        return list.size() > 0;  
    }  
    private boolean isNoSwitch() {  
        long ts = System.currentTimeMillis();  
        UsageStatsManager usageStatsManager = (UsageStatsManager) getApplicationContext()  
                .getSystemService("usagestats");  
        List queryUsageStats = usageStatsManager.queryUsageStats(  
                UsageStatsManager.INTERVAL_BEST, 0, ts);  
        if (queryUsageStats == null || queryUsageStats.isEmpty()) {  
            return false;   
        }  
        return true;  
    } 

    void showToast(String str)
    {
    	Toast.makeText(getApplicationContext(), str, Toast.LENGTH_LONG).show();
    }
}

一个死循环来监控栈顶应用，我这里设置的是微博，若发现栈顶是微博，跳出禁止使用页面；

package com.example.lockdemo;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.KeyEvent;

public class LockActivity extends ActionBarActivity{
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.fragment_main);
	}
	
	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		finish();
	}
	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		// TODO Auto-generated method stub
		if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {

			Intent intent = new Intent(Intent.ACTION_MAIN);
			intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
			intent.addCategory(Intent.CATEGORY_HOME);
			startActivity(intent);
			finish();

		}
		return super.onKeyDown(keyCode, event);
	}

}

这里，xml不在附上。系统权限要加上：

ok，搞定了。