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<UsageStats> appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time);
if (appList != null && appList.size() > 0) {
SortedMap<Long, UsageStats> mySortedMap = new TreeMap<Long, UsageStats>();
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<ActivityManager.RunningAppProcessInfo> 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<UsageStats> appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time);
if (appList != null && appList.size() > 0) {
SortedMap<Long, UsageStats> mySortedMap = new TreeMap<Long, UsageStats>();
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<ActivityManager.RunningAppProcessInfo> 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<ResolveInfo> 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<UsageStats> 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：

<uses-permission android:name="android.permission.GET_TASKS" />
<uses-permission xmlns:tools="http://schemas.android.com/tools"
android:name="android.permission.PACKAGE_USAGE_STATS"
tools:ignore="ProtectedPermissions" />ok，搞定了。