[移动开发]Android 刷新时间

数字时钟

一般我们看到需要刷新时间的需求，都会想到使用handler，开启子线程来刷新时间，但用handler发送消息来刷新时间可能会导致内存泄露，不够稳定，所以我们可以直接利用系统的广播来实现功能。

系统每分钟都会发送广播:Intent.ACTION_TIME_TICK

public class NumberActivity extends AppCompatActivity {

    private TextView tevtView;
    private MyBroadcastReceiver myBroadcastReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_number);
        tevtView=findViewById(R.id.num);
        init();
    }
    // 初始化方法
    public void init() {
        // 新时间
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日HH时mm分", Locale.getDefault());
        tevtView.setText(sdf.format(new Date()));
        // 更新时间的广播
        IntentFilter filter=new IntentFilter();
        filter.addAction(Intent.ACTION_TIME_TICK);
        myBroadcastReceiver=new MyBroadcastReceiver();
        registerReceiver(myBroadcastReceiver,filter);
    }

    class MyBroadcastReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            assert action != null;
                if (action.equals(Intent.ACTION_TIME_TICK)) {
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日HH时mm分", Locale.getDefault());
                tevtView.setText(sdf.format(new Date()));
            }
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // 注销广播
        unregisterReceiver(myBroadcastReceiver);
    }

}