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Widget是一个可以添加在别的应用程序中的”小部件”，我们可以使用自定义的Widget远程控制我们的程序做一些事情。一般用于在桌面上添加一个小部件，现在我们开始小部件的学习。
目录导航：
一、 WidGet的特点：
二、 WidGet的使用步骤：
按照上述所说，我们开始WidGet的实例说明：
一、 在layout中创建一个WidGet的布局文件：widget.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#09C" android:padding="@dimen/widget_margin"> <TextView android:id="@+id/appwidget_text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:layout_margin="8dp" android:background="#09C" android:contentDescription="@string/appwidget_text" android:text="@string/appwidget_text" android:textColor="#ffffff" android:textSize="24sp" android:textStyle="bold|italic" /> </RelativeLayout>
二、 创建一个资源文件夹xml，添加一个widget属性的配置xml文件：widget_info.xml
<?xml version="1.0" encoding="utf-8"?> <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android" android:configure="com.example.linux.listviewtest.MainActivity" android:initialKeyguardLayout="@layout/widget" android:initialLayout="@layout/widget" android:minHeight="40dp" android:minWidth="250dp" android:previewImage="@drawable/example_appwidget_preview" android:resizeMode="horizontal|vertical" android:updatePeriodMillis="86400000" android:widgetCategory="home_screen"> </appwidget-provider>
三、 创建一个继承AppWidgetProvider的java类：widget
package xml; import android.appwidget.AppWidgetManager; import android.appwidget.AppWidgetProvider; import android.content.Context; import android.content.Intent; import android.util.Log; import android.widget.Toast; import com.example.linux.listviewtest.TimerService; /** * writer: huhx * Implementation of App Widget functionality. */ public class widget extends AppWidgetProvider { private final static String TAG = "WidGetTest"; public widget() { Log.i(TAG, "widget constructor."); } // 当一个或多个小组件的实例被删除时调用 @Override public void onDeleted(Context context, int[] appWidgetIds) { Log.i(TAG, "on deleted"); super.onDeleted(context, appWidgetIds); } // 当最后一个这样的小组件被删除 @Override public void onDisabled(Context context) { super.onDisabled(context); Log.i(TAG, "on disable"); context.stopService(new Intent(context, TimerService.class)); } // 当这样的小组件被初始化时，也就是当小组件被拖到桌面 @Override public void onEnabled(Context context) { super.onEnabled(context); Log.i(TAG, "on enable"); context.startService(new Intent(context, TimerService.class)); } // to dispatch calls to the various other methods on AppWidgetProvider. @Override public void onReceive(Context context, Intent intent) { Log.i(TAG, "on receive"); super.onReceive(context, intent); } // 小组件的更新 @Override public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) { super.onUpdate(context, appWidgetManager, appWidgetIds); } }
四、 创建一个更新时间的服务类：TimerService
package com.example.linux.listviewtest; import android.app.Service; import android.appwidget.AppWidgetManager; import android.content.ComponentName; import android.content.Intent; import android.os.IBinder; import android.util.Log; import android.widget.RemoteViews; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Timer; import java.util.TimerTask; import xml.widget; public class TimerService extends Service { private final static String TAG = "WidGetTest"; private Timer timer; private SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); public TimerService() { Log.i(TAG, "timer service constructor"); } @Override public IBinder onBind(Intent intent) { Log.i(TAG, "on bind"); return null; } @Override public void onCreate() { super.onCreate(); Log.i(TAG, "on create"); timer = new Timer(); timer.schedule(new TimerTask() { @Override public void run() { updateViews(); } }, 0, 1000); } private void updateViews() { Log.i(TAG, "update views"); String time = simpleDateFormat.format(new Date()); RemoteViews remoteViews = new RemoteViews(getPackageName(), R.layout.widget); remoteViews.setTextViewText(R.id.appwidget_text, time); AppWidgetManager manager = AppWidgetManager.getInstance(getApplicationContext()); ComponentName name = new ComponentName(getApplicationContext(), widget.class); manager.updateAppWidget(name, remoteViews); } @Override public void onDestroy() { super.onDestroy(); timer = null; } }
五、 在AndroidManifest.xml中，注册服务和接收器：
<activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <service android:name=".TimerService" android:enabled="true" android:exported="true" /> <receiver android:name="xml.widget"> <intent-filter> <action android:name="android.appwidget.action.APPWIDGET_UPDATE" /> </intent-filter> <meta-data android:name="android.appwidget.provider" android:resource="@xml/widget_info" /> </receiver>
六、 在MainActivity中使用：
package com.example.linux.listviewtest; import android.appwidget.AppWidgetManager; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; public class MainActivity extends AppCompatActivity { private final static String TAG = "WidGetTest"; int mAppWidgetId; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Log.i(TAG, " on main create ... "); setResult(RESULT_CANCELED); // Find the widget id from the intent. Intent intent = getIntent(); Bundle extras = intent.getExtras(); if (extras != null) { mAppWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID); } // If they gave us an intent without the widget id, just bail. if (mAppWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) { finish(); } // return OK Intent resultValue = new Intent(); resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId); setResult(RESULT_OK, resultValue); finish(); } }
七、 运行效果如下截图以及打印的日志如下：
03-26 09:21:03.138 27090-27090/com.example.linux.listviewtest I/WidGetTest: widget constructor. 03-26 09:21:03.140 27090-27090/com.example.linux.listviewtest I/WidGetTest: on receive 03-26 09:21:03.140 27090-27090/com.example.linux.listviewtest I/WidGetTest: on enable 03-26 09:21:03.156 27090-27090/com.example.linux.listviewtest I/WidGetTest: timer service constructor 03-26 09:21:03.156 27090-27090/com.example.linux.listviewtest I/WidGetTest: on create 03-26 09:21:03.161 27090-27090/com.example.linux.listviewtest I/WidGetTest: widget constructor. 03-26 09:21:03.161 27090-27090/com.example.linux.listviewtest I/WidGetTest: on receive 03-26 09:21:03.173 27090-27483/com.example.linux.listviewtest I/WidGetTest: update views 03-26 09:21:03.198 27090-27090/com.example.linux.listviewtest I/WidGetTest: on main create ... 03-26 09:21:03.237 27090-27090/com.example.linux.listviewtest I/WidGetTest: widget constructor. 03-26 09:21:03.237 27090-27090/com.example.linux.listviewtest I/WidGetTest: on receive 03-26 09:21:04.173 27090-27483/com.example.linux.listviewtest I/WidGetTest: update views 03-26 09:21:05.214 27090-27483/com.example.linux.listviewtest I/WidGetTest: update views
.......
03-26 09:24:10.719 30093-30093/com.example.linux.listviewtest I/WidGetTest: widget constructor. 03-26 09:24:10.719 30093-30093/com.example.linux.listviewtest I/WidGetTest: on receive 03-26 09:24:10.719 30093-30093/com.example.linux.listviewtest I/WidGetTest: on deleted 03-26 09:24:10.765 30093-30093/com.example.linux.listviewtest I/WidGetTest: widget constructor. 03-26 09:24:10.765 30093-30093/com.example.linux.listviewtest I/WidGetTest: on receive 03-26 09:24:10.766 30093-30093/com.example.linux.listviewtest I/WidGetTest: on disable
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原文地址：http://www.cnblogs.com/huhx/p/widget.html
