1. 一个AppWidgetProviderInfo对象
这个对象通常是在 res/xml目录里设置的
2. 一个AppWidgetProvider类的实现
通常是需要创建一个AppWidgetProvider类的子类，来实现自定义小应用update, enabled, disabled和删除时触发的方法。
3. 一个布局
这个布局是widget初始启动时出现的布局。
举一个最最简单的例子:
1. 先在AndroidManifest.xml中定义桌面小应用
<receiver
android:name=".android.widget.NoteWidgetProvider"
android:label="@string/app_widget_notes" >
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
</intent-filter>
<meta-data
android:name="android.appwidget.provider"
android:resource="@xml/widget_note_info" />
</receiver>
2. 在 res / xml 目录下设置应用的基本信息
xml/widget_note_info.xml
<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider
xmlns:android="http://schemas.android.com/apk/res/android"
android:initialLayout="@layout/widget_note"
android:minWidth="294dip"
android:minHeight="294dip">
</appwidget-provider>
3. 在 res / layout 目录下设置应用启动的初始布局
layout/widget_note.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="294dip"
android:layout_height="294dip">
<ImageView
android:id="@+id/widget_bg_image"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<TextView
android:id="@+id/widget_text"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:paddingTop="40dip"
android:paddingLeft="15dip"
android:paddingRight="15dip"
android:textSize="14sp"
android:textColor="#FF663300"
android:maxLines="12"
android:lineSpacingMultiplier="1.2" />
</FrameLayout>
4. java源码实现AppWidgetProvider类中的自定义update, enable, disable, delete方法
public class NoteWidgetProvider extends AppWidgetProvider {
private static final String TAG = NoteWidgetProvider.class.getSimpleName();
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager,
int[] appWidgetIds) {
ComponentName thisWidget = new ComponentName(context, NoteWidgetProvider.class);
int[] allWidgetIds = appWidgetManager.getAppWidgetIds(thisWidget);
for (int i = 0; i < allWidgetIds.length; i++) {
int widgetId = allWidgetIds[i];
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_note);
remoteViews.setImageViewResource(R.id.widget_bg_image, R.drawable.empty_sketchy);
Intent intent = new Intent(context, NoteWidgetProvider.class);
intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, appWidgetIds);
appWidgetManager.updateAppWidget(widgetId, remoteViews);
}
}
}
5. 如果要点击 widget 启动一个 activity, 需要修改4中的代码如下：
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager,
int[] appWidgetIds) {
ComponentName thisWidget = new ComponentName(context, NoteWidgetProvider.class);
int[] allWidgetIds = appWidgetManager.getAppWidgetIds(thisWidget);
for (int i = 0; i < allWidgetIds.length; i++) {
int widgetId = allWidgetIds[i];
Intent intent = new Intent(context, NoteEditActivity.class);
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, widgetId);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_note);
remoteViews.setImageViewResource(R.id.widget_bg_image, R.drawable.empty_sketchy);
remoteViews.setOnClickPendingIntent(R.id.widget_text, pendingIntent);
appWidgetManager.updateAppWidget(widgetId, remoteViews);
}
}
6. NoteEditActivity的布局
<?xml version="1.0" encoding="utf-8"?> <LinearLayout android:id="@+id/widget83" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"> <LinearLayout android:id="@+id/layout_notes" android:layout_width="fill_parent" android:layout_height="388dp" android:orientation="vertical"> <EditText android:id="@+id/edit_notes" android:layout_width="fill_parent" android:layout_height="fill_parent" android:hint="Please input!" android:textSize="18sp" /> </LinearLayout> <Button android:id="@+id/button_save" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Save" android:gravity="center" android:layout_gravity="right" /> </LinearLayout>
7. 点击 NoteEditActivity 的按钮，返回widget页面的方法
public class NoteNote extends Activity {
private static final String TAG = NoteNote.class.getSimpleName();
private int mAppWidgetId;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
this.setContentView(R.layout.note_edit);
Intent t = getIntent();
mAppWidgetId = t.getExtras().getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
Log.i(TAG,"mAppWidgetId=" + mAppWidgetId);
Button b = (Button) this.findViewById(R.id.button_save);
b.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
RemoteViews views = new RemoteViews(getApplicationContext().getPackageName(), R.layout.widget_note);
views.setImageViewResource(R.id.widget_bg_image, R.drawable.empty_sketchy);
//设置完成后需要获取AppWidgetManager，对指定的widget进行更新，才能使设置生效。
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(getApplicationContext());
appWidgetManager.updateAppWidget(mAppWidgetId, views);
finish();
}
});
}
8. 在WIDGET里输入点内容，使用最简单的方法保存起来，然后更新WIDGET时显示被修改的内容。
public class NoteWidgetProvider extends AppWidgetProvider {
public void onUpdate(Context context, AppWidgetManager appWidgetManager,
int[] appWidgetIds) {
for (int i = 0; i < allWidgetIds.length; i++) {
int widgetId = allWidgetIds[i];
// 显示保存的输入内容
SharedPreferences settings = context.getSharedPreferences("MyPrefsFile", Context.MODE_PRIVATE);
String notes = settings.getString("my_abcdefg", "");
Log.i(TAG,"NOTES=" + notes);
Intent intent = new Intent(context, NoteNote.class);
intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, widgetId);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_note);
remoteViews.setImageViewResource(R.id.widget_bg_image, R.drawable.empty_sketchy);
// 将保存的输入内容显示在WIDGET的TEXTVIEW里。
remoteViews.setTextViewText(R.id.widget_text, notes);
remoteViews.setOnClickPendingIntent(R.id.widget_text, pendingIntent);
appWidgetManager.updateAppWidget(widgetId, remoteViews);
}
}
}
// 将输入的信息保存起来
public class NoteNote extends Activity {
.......
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.note_edit);
Intent t = getIntent();
mAppWidgetId = t.getExtras().getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
// 将保存的信息显示在输入框内
SharedPreferences settings = getSharedPreferences("MyPrefsFile", Context.MODE_PRIVATE);
notes = settings.getString("my_abcdefg", "");
Log.i(TAG,"NOTES=" + notes);
et = (EditText) findViewById(R.id.edit_notes);
et.setText(notes);
Button b = (Button) this.findViewById(R.id.button_save);
b.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
if(et!=null) notes = et.getText().toString();
Log.i(TAG,"after onclick, text is =" + notes);
// 将修改后的输入信息保存起来
SharedPreferences.Editor editor = getSharedPreferences("MyPrefsFile", Context.MODE_PRIVATE).edit();
editor.putString("my_abcdefg", notes);
editor.commit();
// 调用widget页面，并将修改后的内容显示在widget内。
RemoteViews views = new RemoteViews(getApplicationContext().getPackageName(), R.layout.widget_note);
views.setImageViewResource(R.id.widget_bg_image, R.drawable.empty_sketchy);
views.setTextViewText(R.id.widget_text, notes);
//设置完成后需要获取AppWidgetManager，对指定的widget进行更新，才能使设置生效。
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(getApplicationContext());
appWidgetManager.updateAppWidget(mAppWidgetId, views);
finish();
}
});
}
}