时间检查每一秒钟，然后调整Ondesroy

Question

我提出了免费获取不同促销代码的申请，但我想限制人们每5小时服用一次促销代码（即，单击"获取"，获得促销代码和按钮不活动5个小时），但我遇到了一些问题：

1. 如何设置每秒接收时间并在应用程序运行时准确计算差异（在代码中，仅当应用程序被最小化并在适当的时间之后部署应用程序时，它才能使用）？
）？

2. 当应用程序关闭时，如何保存.setEnabled（）按钮（true或fals）的值（我知道在ondestroy中，但是我找不到要找到的命令）？预先感谢！

   Button button;
   TextView textView;
   private String TAG;
   SharedPreferences preferences;
   Long oldTime;
   Long newTime;
   Long current;
   
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       button = findViewById(R.id.button);
       textView = findViewById(R.id.textView);
       preferences = PreferenceManager.getDefaultSharedPreferences(this);
   
   
       button.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               button.setEnabled(false);
               Date date = new Date();
               long startTime = date.getTime();
               Log.d(TAG,"Time: " + startTime);
               SharedPreferences.Editor editor = preferences.edit();
               editor.putLong("Tl", startTime);
               editor.apply();
               oldTime = preferences.getLong("Tl", 0);
               Log.d(TAG, "Old Time2: " + oldTime);
               newTime = System.currentTimeMillis();
               Log.d(TAG, "New Time: " + newTime);
               current = newTime - oldTime;
               Log.d(TAG, "Current: " + current);
           }
       });
   
       if (current != null) {
           if (current >= 10000) {
               button.setEnabled(true);
           }
       }
   }
   @Override
   protected void onStart() {
       super.onStart();
   }
   @Override
   protected void onRestart() {
       super.onRestart();
       oldTime = preferences.getLong("Tl", 0);
       Log.d(TAG, "Old Time2: " + oldTime);
       newTime = System.currentTimeMillis();
       Log.d(TAG, "New Time: " + newTime);
       current = newTime - oldTime;
       Log.d(TAG, "Current: " + current);
       if (current >= 10000) {
           button.setEnabled(true);
       }
   }
   
   @Override
   protected void onDestroy() {
       super.onDestroy();
       button.onSaveInstanceState();
   }
   

Answer 1

如何设置每秒接收时间并计算 应用程序运行时的确切区别（在代码中 仅当将应用程序最小化并且应用程序是 在适当的时间后部署）？

无需检查每一秒即可启用/禁用升级代码按钮。如果您需要在特定时间（在情况下为5个小时）执行操作（启用/禁用按钮），则应使用AlarmManager API。无论您的应用是否正在运行，它都会工作。

解决方案：您可以按照以下示例在特定时间后执行操作。

步骤1：定义AlarmBroadcastReceiver类，此类将在特定时间后由AlarmManager调用。

public class AlarmBroadcastReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        PreferenceManager.getDefaultSharedPreferences(context.getApplicationContext())
                .edit()
                .putBoolean("enabled", true)
                .apply();
        Intent i = new Intent("updatePromoteCode");
        LocalBroadcastManager.getInstance(context).sendBroadcast(i);
    }
}

然后在清单文件中注册。

<receiver android:name=".AlarmBroadcastReceiver"/>

步骤2：在MainActivity中写代码，其布局只有一个名为button_get_promote_code的按钮。

public class MainActivity extends AppCompatActivity {
    private static final int PROMOTE_CODE_AVAILABLE_INTERVAL = 5 * 60 * 60 * 1000; // In milliseconds.
    private AlarmManager mAlarmManager;
    private Button mGetPromoteCodeButton;
    private BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            // Enable the button after the specific time.
            mGetPromoteCodeButton.setEnabled(true);
        }
    };
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mAlarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
        Intent intent = new Intent(this, AlarmBroadcastReceiver.class);
        final PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
        mGetPromoteCodeButton = findViewById(R.id.button_get_promote_code);
        mGetPromoteCodeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Disable the button after users click on it.
                v.setEnabled(false);
                // Save a variable named `enabled` in prefs which indicates status of the button.
                PreferenceManager.getDefaultSharedPreferences(MainActivity.this.getApplicationContext())
                        .edit()
                        .putBoolean("enabled", false)
                        .apply();
                // Schedule an action (enable the button) after a specific time by using AlarmManager.
                mAlarmManager.set(AlarmManager.RTC_WAKEUP,
                        System.currentTimeMillis() + PROMOTE_CODE_AVAILABLE_INTERVAL,
                        pendingIntent);
            }
        });
    }
    @Override
    protected void onStart() {
        super.onStart();
        // This receiver will receive an action which sent from `onReceive` method of `AlarmBroadcastReceiver`.
        IntentFilter intentFilter = new IntentFilter("updatePromoteCode");
        LocalBroadcastManager.getInstance(this).registerReceiver(mBroadcastReceiver, intentFilter);
        // When this activity goes to foreground, we will set its status based on `enabled` variable in prefs.
        boolean enabled = PreferenceManager.getDefaultSharedPreferences(MainActivity.this.getApplicationContext())
                .getBoolean("enabled", true);
        mGetPromoteCodeButton.setEnabled(enabled);
    }
    @Override
    protected void onStop() {
        // Unregister the receiver.
        LocalBroadcastManager.getInstance(this).unregisterReceiver(mBroadcastReceiver);
        super.onStop();
    }
}