Android的日期种及Handler的使用

??????? 在此处可完全不用Handler，只是了解用法，Handler是为了解决android的多线程问题--Android平台下不允许新启动的线程访问该Activity里面的组件，这样会导致新启动的线程无法动态改变界面组件中的属性值，这就需要Handler的消息传递机制来解决了。

--》1.在新启动的线程中发送消息。（当然啦，这里并非新启动的线程）

Message msg = new Message();msg.what = DATE_ID;myHandler.sendMessage(msg);

?-->2.在主线程中获取、处理消息。

private static int DATE_ID = 0;private static int TIME_ID = 1;Handler myHandler = new Handler(){		@Override		public void handleMessage(Message msg) {			super.handleMessage(msg);			switch(msg.what){			case 0:				setCurrentDate(year, month, day);				break;			case 1:				setCurrentTime(hour, minute);				break;			}		}	};

?小实例的代码如下：

public class MainActivity extends Activity implements OnClickListener{	private EditText showDate, showTime;	private Button pickDate, pickTime;	private int year, month, day, hour, minute;	private static int DATE_ID = 0;	private static int TIME_ID = 1;		@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);				showDate = (EditText)findViewById(R.id.showdate);		showTime = (EditText)findViewById(R.id.showtime);		pickDate = (Button)findViewById(R.id.pickdate);		pickTime = (Button)findViewById(R.id.picktime);				pickDate.setOnClickListener(this);		pickTime.setOnClickListener(this);				Calendar c = Calendar.getInstance();		year = c.get(Calendar.YEAR);		month = c.get(Calendar.MONTH);		day = c.get(Calendar.DAY_OF_MONTH);				hour = c.get(Calendar.HOUR_OF_DAY);		minute = c.get(Calendar.MINUTE);				setCurrentDate(year, month, day);		setCurrentTime(hour, minute);			}		public void setCurrentDate(int year, int month, int day){		showDate.setText(year + "-" + (month+1) + "-" + day);	}		public void setCurrentTime(int hour, int minute){		showTime.setText(hour + ":" + minute);	}	@Override	public void onClick(View v) {		Calendar c = Calendar.getInstance();		switch(v.getId()){		case R.id.pickdate:			year = c.get(Calendar.YEAR);			month = c.get(Calendar.MONTH);			day = c.get(Calendar.DAY_OF_MONTH);			new DatePickerDialog(					MainActivity.this, 					new OnDateSetListener() {						// DatePickerDialog5个参数.1:上下文,2:设置日期的回调.						//可以在里面调用更新ui的方法更新ui,3:45就是初始化时候的年月日了.  						@Override						public void onDateSet(DatePicker view, int year, int monthOfYear,								int dayOfMonth) {							MainActivity.this.year = year;							MainActivity.this.month = monthOfYear;							MainActivity.this.day = dayOfMonth;														Message msg = new Message();							msg.what = DATE_ID;							myHandler.sendMessage(msg);						}					}, year, month, day).show();			break;		case R.id.picktime:			hour = c.get(Calendar.HOUR_OF_DAY);			minute = c.get(Calendar.MINUTE);			new TimePickerDialog(					MainActivity.this, 					new OnTimeSetListener() {										@Override						public void onTimeSet(TimePicker view, int hourOfDay, int minute) {							MainActivity.this.hour = hourOfDay;							MainActivity.this.minute = minute;							Message msg = new Message();							msg.what = TIME_ID;							myHandler.sendMessage(msg);						}					}, hour, minute, true).show();			break;		}	}		Handler myHandler = new Handler(){		@Override		public void handleMessage(Message msg) {			super.handleMessage(msg);			switch(msg.what){			case 0:				setCurrentDate(year, month, day);				break;			case 1:				setCurrentTime(hour, minute);				break;			}		}	};	}

?布局文件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent">        <TextView        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:text="欢迎关注Aaron.Ou Blog" />         <TextView        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:text="日期和时间控件的使用DEMO" />        <LinearLayout         android:orientation="horizontal"         	android:layout_width="fill_parent"        	android:layout_height="wrap_content">         <EditText            android:id="@+id/showdate"            android:layout_width="fill_parent"             android:layout_height="wrap_content"            android:layout_weight="1"/>                <Button            android:id="@+id/pickdate"            android:layout_width="wrap_content"             android:layout_height="wrap_content"            android:text="选择日期"/>        </LinearLayout>         <LinearLayout         android:orientation="horizontal"         	android:layout_width="fill_parent"        	android:layout_height="wrap_content">         <EditText            android:id="@+id/showtime"            android:layout_width="fill_parent"             android:layout_height="wrap_content"            android:layout_weight="1"/>                <Button            android:id="@+id/picktime"            android:layout_width="wrap_content"             android:layout_height="wrap_content"            android:text="选择时间"/>        </LinearLayout> </LinearLayout>

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