【原创】Android之Widget
简介
1 Android widget
Android widget 也称为桌面插件，其是android系统应用开发层面的一部分，但是又有特殊用途，而且会成为整个android系统的亮点。Android中的AppWidget与google widget和中移动的widget并不是一个概念，这里的AppWidget只是把一个进程的控件嵌入到别外一个进程的窗口里的一种方法。
2 AppWidget Framework
2.1 定义
Android系统增加了AppWidget 框架，用以支持widget类型应用的开发。AppWidget 框架主要由两个部件来组成：
（1）AppWidgetService是框架的的核心类，是系统 service之一，它负责widgets的管理工作。加载，删除，定时事件等都需要AppWidgetService的处理。开机自启动的。
AppWidgetService存在的目的主要是解开AppWidgetProvider和AppWidgetHost之间的耦合。如果 AppWidgetProvider和AppWidgetHost的关系固定死了，AppWidget就无法在任意进程里显示了。而有了 AppWidgetService，AppWidgetProvider根本不需要知道自己的AppWidget在哪里显示了。
（2）AppWidgetManager 负责widget视图的实际更新以及相关管理。
2.2 AppWidget Framework的大致流程
1. 编写一个widget（先不考虑后台服务以及用户管理界面等）
实际是写一个事件监听类即一个BroadcastReceiver子类，当然框架已经提供了一个辅助类AppWidgetProvider，实现的类只要实现其方法即可，其中必须实现的方法是onUpdate ，其实就是一个定时事件，widget监听此事件
另外就是规划好视图（layout），将此widget打包安装。
2. 当android系统启动时，AppWidgetService 就将负责检查所有的安装包，将检查
AndroidManifest.xml（不要告诉我不知道，如果不知道可要看看基本开发知识了）
文件中有<metadata android:name="android.appwidget.provider" android:resource="@xml/appwidget_info" />
信息的程序包记录下来
实际是写一个事件监听类即一个BroadcastReceiver子类，当然框架已经提供了一个辅助类AppWidgetProvider，实现的类只要实现其方法即可，其中必须实现的方法是onUpdate ，其实就是一个定时事件，widget监听此事件
另外就是规划好视图（layout），将此widget打包安装。
2. 当android系统启动时，AppWidgetService 就将负责检查所有的安装包，将检查
AndroidManifest.xml（不要告诉我不知道，如果不知道可要看看基本开发知识了）
文件中有<metadata android:name="android.appwidget.provider" android:resource="@xml/appwidget_info" />
信息的程序包记录下来
3. 从用户菜单将已经安装的widget添加到桌面，也就是将widget在桌面上显示出来，这个应该是由AppWidgetService和AppWidgetManager完成的，其中AppWidgetManager 将负责将视图发送到桌面显示出来，并将此widget记录到系统文件中
4. AppWidgetService将根据widget配置中的updatePeriodMillis属性来定时发送ACTION_APPWIDGET_UPDATE事件，此事件将激活widget的事件监听方法onUpdate，此方法将通过AppWidgetManager完成widget内容的更新和其他操作。
4. AppWidgetService将根据widget配置中的updatePeriodMillis属性来定时发送ACTION_APPWIDGET_UPDATE事件，此事件将激活widget的事件监听方法onUpdate，此方法将通过AppWidgetManager完成widget内容的更新和其他操作。
3 AppWidgetHost
AppWidgetHost 是实际控制widget的地方，大家注意，widget不是一个单独的用户界面程序，他必须寄生在某个程序（activity）中，这样如果程序要支持widget寄生就要实现AppWidgetHost，桌面程序（Launcher）就实现了这个接口。
它的主要功能有两个：
o 监听来自AppWidgetService的事件。
o 另外一个功能就是创建AppWidgetHostView。
前面我们说过RemoteViews不是真正的View，只是View的描述，而 AppWidgetHostView才是真正的View。这里先创建AppWidgetHostView，然后通过AppWidgetService查询 appWidgetId对应的RemoteViews，最后把RemoteViews传递给AppWidgetHostView去updateAppWidget。
Host的实现者
AppWidgetHost和AppWidgetHostView是在框架中定义的两个基类。应用程序可以利用这两个类来实现自己的Host。Launcher是缺省的桌面，它是一个Host的实现者。
LauncherAppWidgetHostView扩展了AppWidgetHostView，实现了对长按事件的处理。
LauncherAppWidgetHost扩展了AppWidgetHost，这里只是重载了onCreateView，创建LauncherAppWidgetHostView的实例。
4 AppWidgetHostView
AppWidgetHostView是真正的View，但它只是一个容器，用来容纳实际的AppWidget的View。这个AppWidget的View是根据RemoteViews的描述来创建。
5 AppWidgetProvider
AppWidgetProvider是AppWidget提供者需要实现的接口，它实际上是一个BroadcastReceiver。只不过子类要实现的不再是onReceive，而是转换成了几个新的函数：
1 public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
2 public void onDeleted(Context context, int[] appWidgetIds)
3 public void onEnabled(Context context)
4 public void onDisabled(Context context)
2 public void onDeleted(Context context, int[] appWidgetIds)
3 public void onEnabled(Context context)
4 public void onDisabled(Context context)
这几个函数用来响应AppWidgetService发出的相应的广播消息。
AppWidgetProvider的实现者
作为AppWidgetProvider的实现者，一定要实现onUpdate函数，因为这个函数决定widget的显示方式，如果没有这个函数widget根本没办法出现。
1 void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
onUpdate的实现基本上遵循下面的流程：
o 创建RemoteViews
o 调用AppWidgetManager的updateAppWidget去更新widget.
o 调用AppWidgetManager的updateAppWidget去更新widget.
6 RemoteViews
RemoteViews并不是一个真正的View，它没有实现View的接口，而只是一个用于描述View的实体。比如：创建View需要的资源ID和各个控件的事件响应方法。RemoteViews会通过进程间通信机制传递给AppWidgetHost。
现在我们可以看出，Android中的AppWidget与google widget和中移动的widget并不是一个概念，这里的AppWidget只是把一个进程的控件嵌入到别外一个进程的窗口里的一种方法。View在另 外一个进程里显示，但事件的处理方法还是在原来的进程里。这有点像 X Window中的嵌入式窗口。
组成部分
1 AppWidgetProviderInfo
描述一个App Widget，如App Widget的布局，更新频率，以及AppWidgetProvider类的metadata。这在XML中定义。
一个App Widget的基本属性是通过AppWidgetProviderInfo去定义的，例如它的最小尺寸的布局，它的初始layout，多久更新App Widget，还有（可选）在创建时期的一个配置Activity。在XML资源中定义一个AppWidgetProviderInfo是通过<appwidget-provider>标签，并保存在工程的res/xml/文件夹底下。ApiDemo中的例子 appwidget_provider.xml文件：
<?xml version="1.0" encoding="utf-8"?>
<!-- 86400000 is the value of AlarmManager.INTERVAL_DAY - or once per day. -->
<!-- Copyright (C) 2006 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
android:minWidth="60dp"
android:minHeight="30dp"
android:updatePeriodMillis="86400000"
android:initialLayout="@layout/appwidget_provider"
android:configure="com.example.android.apis.appwidget.ExampleAppWidgetConfigure"
>
</appwidget-provider>
configure 属性是当用户添加一个App Widget前启动的Activity，这个Activity的作用就是配置App Widget的属性。(Optional)
updatePeriodMillis 属性定义了App Widget应该多久向AppWidgetProvider请求更新。实际更新的时间未必能保证及时更新，并且建议尽量不要频繁更新---比如一小时一次去更新电量。也可以容许用户去自定义更新的时间。
重大消息！！！SDK1.5之后此方法android:updatePeriodMillis就失效了，要自己创建service更新。
2 AppWidgetProvider
AppWidgetProvider是BroadcastReceiver的子类，这个类处理App Widget广播。AppWidgetProvider只接收于App Widget有关系的广播，比如App Widget在updated, deleted, enabled, and disabled。当这些广播发生的时候，AppWidgetProvider会调用一下回调方法：
onUpdate(Context, AppWidgetManager, int[])
间隔调用此方法去更新App Widget，间隔时间的设置是在AppWidgetProviderInfo下的updatePeriodMillis属性，同样当用户添加App Widget的时候也被调用。如果你已经声明了一个configuration Activity，用户添加App Widget的时候就不会调用onUpdate，但是在随后的更新中依然会被调用。
onDeleted(Context, int[])
当App Widget 从App Widget host 中删除的时候调用。
onEnabled(Context)
当App Widget第一次创建的时候调用。比如，当用户增加两个同样的App Widget时候，这个方法只在第一次去调用。如果你需要打开一个新的数据库或者其他的设置，而这在所有的App Widgets只需要设置一次的情况下，这个是最好的地方去实现它们。
onDisabled(Context)
当App Widget的最后一个实例从App Widget host中被删除的时候调用。这里可以做一些在onEnabled(Context)中相反的操作，比如删除临时数据库。
onReceive(Context, Intent)
每一个广播的产生都会调用此方法，而且是在上面方法之前被调用。通常不需要实现此方法。
在AppWidgetProvider中最重要的callback就是onUpdated()，如果你的App Widget接收用户交互事件，就需要在这个callback里面进行处理。
ApiDemo中的例子，ExampleAppWidgetProvider.java文件
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.appwidget;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.pm.PackageManager;
import android.os.SystemClock;
import android.util.Log;
import android.widget.RemoteViews;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;
/**
* A widget provider. We have a string that we pull from a preference in order to show
* the configuration settings and the current time when the widget was updated. We also
* register a BroadcastReceiver for time-changed and timezone-changed broadcasts, and
* update then too.
*
* <p>See also the following files:
* <ul>
* <li>ExampleAppWidgetConfigure.java</li>
* <li>ExampleBroadcastReceiver.java</li>
* <li>res/layout/appwidget_configure.xml</li>
* <li>res/layout/appwidget_provider.xml</li>
* <li>res/xml/appwidget_provider.xml</li>
* </ul>
*/
public class ExampleAppWidgetProvider extends AppWidgetProvider {
// log tag
private static final String TAG = "ExampleAppWidgetProvider";
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
Log.d(TAG, "onUpdate");
// For each widget that needs an update, get the text that we should display:
// - Create a RemoteViews object for it
// - Set the text in the RemoteViews object
// - Tell the AppWidgetManager to show that views object for the widget.
final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
int appWidgetId = appWidgetIds[i];
String titlePrefix = ExampleAppWidgetConfigure.loadTitlePref(context, appWidgetId);
updateAppWidget(context, appWidgetManager, appWidgetId, titlePrefix);
}
}
@Override
public void onDeleted(Context context, int[] appWidgetIds) {
Log.d(TAG, "onDeleted");
// When the user deletes the widget, delete the preference associated with it.
final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
ExampleAppWidgetConfigure.deleteTitlePref(context, appWidgetIds[i]);
}
}
@Override
public void onEnabled(Context context) {
Log.d(TAG, "onEnabled");
// When the first widget is created, register for the TIMEZONE_CHANGED and TIME_CHANGED
// broadcasts. We don't want to be listening for these if nobody has our widget active.
// This setting is sticky across reboots, but that doesn't matter, because this will
// be called after boot if there is a widget instance for this provider.
PackageManager pm = context.getPackageManager();
pm.setComponentEnabledSetting(
new ComponentName("com.example.android.apis", ".appwidget.ExampleBroadcastReceiver"),
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP);
}
@Override
public void onDisabled(Context context) {
// When the first widget is created, stop listening for the TIMEZONE_CHANGED and
// TIME_CHANGED broadcasts.
Log.d(TAG, "onDisabled");
PackageManager pm = context.getPackageManager();
pm.setComponentEnabledSetting(
new ComponentName("com.example.android.apis", ".appwidget.ExampleBroadcastReceiver"),
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP);
}
static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
int appWidgetId, String titlePrefix) {
Log.d(TAG, "updateAppWidget appWidgetId=" + appWidgetId + " titlePrefix=" + titlePrefix);
// Getting the string this way allows the string to be localized. The format
// string is filled in using java.util.Formatter-style format strings.
CharSequence text = context.getString(R.string.appwidget_text_format,
ExampleAppWidgetConfigure.loadTitlePref(context, appWidgetId),
"0x" + Long.toHexString(SystemClock.elapsedRealtime()));
// Construct the RemoteViews object. It takes the package name (in our case, it's our
// package, but it needs this because on the other side it's the widget host inflating
// the layout from our package).
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider);
views.setTextViewText(R.id.appwidget_text, text);
// Tell the widget manager
appWidgetManager.updateAppWidget(appWidgetId, views);
}
}
如果你需要一个带有Button的App Widget，点击Button去启动一个Activity，下面就是AppWidgetProvider的实现方法：* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.appwidget;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.pm.PackageManager;
import android.os.SystemClock;
import android.util.Log;
import android.widget.RemoteViews;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;
/**
* A widget provider. We have a string that we pull from a preference in order to show
* the configuration settings and the current time when the widget was updated. We also
* register a BroadcastReceiver for time-changed and timezone-changed broadcasts, and
* update then too.
*
* <p>See also the following files:
* <ul>
* <li>ExampleAppWidgetConfigure.java</li>
* <li>ExampleBroadcastReceiver.java</li>
* <li>res/layout/appwidget_configure.xml</li>
* <li>res/layout/appwidget_provider.xml</li>
* <li>res/xml/appwidget_provider.xml</li>
* </ul>
*/
public class ExampleAppWidgetProvider extends AppWidgetProvider {
// log tag
private static final String TAG = "ExampleAppWidgetProvider";
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
Log.d(TAG, "onUpdate");
// For each widget that needs an update, get the text that we should display:
// - Create a RemoteViews object for it
// - Set the text in the RemoteViews object
// - Tell the AppWidgetManager to show that views object for the widget.
final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
int appWidgetId = appWidgetIds[i];
String titlePrefix = ExampleAppWidgetConfigure.loadTitlePref(context, appWidgetId);
updateAppWidget(context, appWidgetManager, appWidgetId, titlePrefix);
}
}
@Override
public void onDeleted(Context context, int[] appWidgetIds) {
Log.d(TAG, "onDeleted");
// When the user deletes the widget, delete the preference associated with it.
final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
ExampleAppWidgetConfigure.deleteTitlePref(context, appWidgetIds[i]);
}
}
@Override
public void onEnabled(Context context) {
Log.d(TAG, "onEnabled");
// When the first widget is created, register for the TIMEZONE_CHANGED and TIME_CHANGED
// broadcasts. We don't want to be listening for these if nobody has our widget active.
// This setting is sticky across reboots, but that doesn't matter, because this will
// be called after boot if there is a widget instance for this provider.
PackageManager pm = context.getPackageManager();
pm.setComponentEnabledSetting(
new ComponentName("com.example.android.apis", ".appwidget.ExampleBroadcastReceiver"),
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP);
}
@Override
public void onDisabled(Context context) {
// When the first widget is created, stop listening for the TIMEZONE_CHANGED and
// TIME_CHANGED broadcasts.
Log.d(TAG, "onDisabled");
PackageManager pm = context.getPackageManager();
pm.setComponentEnabledSetting(
new ComponentName("com.example.android.apis", ".appwidget.ExampleBroadcastReceiver"),
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP);
}
static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
int appWidgetId, String titlePrefix) {
Log.d(TAG, "updateAppWidget appWidgetId=" + appWidgetId + " titlePrefix=" + titlePrefix);
// Getting the string this way allows the string to be localized. The format
// string is filled in using java.util.Formatter-style format strings.
CharSequence text = context.getString(R.string.appwidget_text_format,
ExampleAppWidgetConfigure.loadTitlePref(context, appWidgetId),
"0x" + Long.toHexString(SystemClock.elapsedRealtime()));
// Construct the RemoteViews object. It takes the package name (in our case, it's our
// package, but it needs this because on the other side it's the widget host inflating
// the layout from our package).
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider);
views.setTextViewText(R.id.appwidget_text, text);
// Tell the widget manager
appWidgetManager.updateAppWidget(appWidgetId, views);
}
}
public class ExampleAppWidgetProvider extends AppWidgetProvider {
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
final int N = appWidgetIds.length;
// Perform this loop procedure for each App Widget that belongs to this provider
for (int i=0; i<N; i++) {
int appWidgetId = appWidgetIds[i];
// Create an Intent to launch ExampleActivity
Intent intent = new Intent(context, ExampleActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
// Get the layout for the App Widget and attach an on-click listener to the button
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider_layout);
views.setOnClickPendingIntent(R.id.button, pendingIntent);
// Tell the AppWidgetManager to perform an update on the current App Widget
appWidgetManager.updateAppWidget(appWidgetId, views);
}
}
}
3 View layout
只要你熟悉用xml怎么去定义layout的话，为App Widget定义一个layout还是很简单的。但是由于App Widget的布局是基于RemoteViews，所以只能使用RemoteViews所支持的layout或者view。
RemoteViews支持的layout和view如下：
Layout – FrameLayout 、LinearLayout、 RelativeLayou
View -- Analog、Clock、 Button、 Chronometer 、ImageButton、 ImageView、 ProgressBar 、TextView
注意：继承这些类的子类同样不支持。
ApiDemo例子，appwidget_provider.xml文件。
<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2006 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/appwidget_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#ff000000"
/>
4 App Widget Configuration Activity
这个Activity将通过App Widget自动启动，用户可以给App Widget设置有用的参数，比如App Widget的颜色、大小、更新时间或者其他的属性。
在AndroidManifes.xml中定义这个Activity和一般定义Activity基本没有区别，App Widget host启动这个Activity需要一个Action，所以：
<activity android:name=".ExampleAppWidgetConfigure">
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" />
</intent-filter>
</activity>
同样这个Activity必须在AppWidgetProviderInfo XML文件中定义android:configure。
值得注意的是App Widget host调用configuration Activity，configuration Activity必须要返回一个结果（必须包含App Widget ID）saved in the Intent extras as EXTRA_APPWIDGET_ID。
ApiDemo例子，ExampleAppWidgetConfigure.java文件：
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.appwidget;
import android.app.Activity;
import android.appwidget.AppWidgetManager;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import java.util.ArrayList;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;
/**
* The configuration screen for the ExampleAppWidgetProvider widget sample.
*/
public class ExampleAppWidgetConfigure extends Activity {
static final String TAG = "ExampleAppWidgetConfigure";
private static final String PREFS_NAME
= "com.example.android.apis.appwidget.ExampleAppWidgetProvider";
private static final String PREF_PREFIX_KEY = "prefix_";
int mAppWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
EditText mAppWidgetPrefix;
public ExampleAppWidgetConfigure() {
super();
}
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// Set the result to CANCELED. This will cause the widget host to cancel
// out of the widget placement if they press the back button.
setResult(RESULT_CANCELED);
// Set the view layout resource to use.
setContentView(R.layout.appwidget_configure);
// Find the EditText
mAppWidgetPrefix = (EditText)findViewById(R.id.appwidget_prefix);
// Bind the action for the save button.
findViewById(R.id.save_button).setOnClickListener(mOnClickListener);
// 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();
}
mAppWidgetPrefix.setText(loadTitlePref(ExampleAppWidgetConfigure.this, mAppWidgetId));
}
View.OnClickListener mOnClickListener = new View.OnClickListener() {
public void onClick(View v) {
final Context context = ExampleAppWidgetConfigure.this;
// When the button is clicked, save the string in our prefs and return that they
// clicked OK.
String titlePrefix = mAppWidgetPrefix.getText().toString();
saveTitlePref(context, mAppWidgetId, titlePrefix);
// Push widget update to surface with newly set prefix
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
ExampleAppWidgetProvider.updateAppWidget(context, appWidgetManager,
mAppWidgetId, titlePrefix);
// Make sure we pass back the original appWidgetId
Intent resultValue = new Intent();
resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId);
setResult(RESULT_OK, resultValue);
finish();
}
};
// Write the prefix to the SharedPreferences object for this widget
static void saveTitlePref(Context context, int appWidgetId, String text) {
SharedPreferences.Editor prefs = context.getSharedPreferences(PREFS_NAME, 0).edit();
prefs.putString(PREF_PREFIX_KEY + appWidgetId, text);
prefs.commit();
}
// Read the prefix from the SharedPreferences object for this widget.
// If there is no preference saved, get the default from a resource
static String loadTitlePref(Context context, int appWidgetId) {
SharedPreferences prefs = context.getSharedPreferences(PREFS_NAME, 0);
String prefix = prefs.getString(PREF_PREFIX_KEY + appWidgetId, null);
if (prefix != null) {
return prefix;
} else {
return context.getString(R.string.appwidget_prefix_default);
}
}
static void deleteTitlePref(Context context, int appWidgetId) {
}
static void loadAllTitlePrefs(Context context, ArrayList<Integer> appWidgetIds,
ArrayList<String> texts) {
}
}
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.appwidget;
import android.app.Activity;
import android.appwidget.AppWidgetManager;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import java.util.ArrayList;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;
/**
* The configuration screen for the ExampleAppWidgetProvider widget sample.
*/
public class ExampleAppWidgetConfigure extends Activity {
static final String TAG = "ExampleAppWidgetConfigure";
private static final String PREFS_NAME
= "com.example.android.apis.appwidget.ExampleAppWidgetProvider";
private static final String PREF_PREFIX_KEY = "prefix_";
int mAppWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
EditText mAppWidgetPrefix;
public ExampleAppWidgetConfigure() {
super();
}
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// Set the result to CANCELED. This will cause the widget host to cancel
// out of the widget placement if they press the back button.
setResult(RESULT_CANCELED);
// Set the view layout resource to use.
setContentView(R.layout.appwidget_configure);
// Find the EditText
mAppWidgetPrefix = (EditText)findViewById(R.id.appwidget_prefix);
// Bind the action for the save button.
findViewById(R.id.save_button).setOnClickListener(mOnClickListener);
// 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();
}
mAppWidgetPrefix.setText(loadTitlePref(ExampleAppWidgetConfigure.this, mAppWidgetId));
}
View.OnClickListener mOnClickListener = new View.OnClickListener() {
public void onClick(View v) {
final Context context = ExampleAppWidgetConfigure.this;
// When the button is clicked, save the string in our prefs and return that they
// clicked OK.
String titlePrefix = mAppWidgetPrefix.getText().toString();
saveTitlePref(context, mAppWidgetId, titlePrefix);
// Push widget update to surface with newly set prefix
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
ExampleAppWidgetProvider.updateAppWidget(context, appWidgetManager,
mAppWidgetId, titlePrefix);
// Make sure we pass back the original appWidgetId
Intent resultValue = new Intent();
resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId);
setResult(RESULT_OK, resultValue);
finish();
}
};
// Write the prefix to the SharedPreferences object for this widget
static void saveTitlePref(Context context, int appWidgetId, String text) {
SharedPreferences.Editor prefs = context.getSharedPreferences(PREFS_NAME, 0).edit();
prefs.putString(PREF_PREFIX_KEY + appWidgetId, text);
prefs.commit();
}
// Read the prefix from the SharedPreferences object for this widget.
// If there is no preference saved, get the default from a resource
static String loadTitlePref(Context context, int appWidgetId) {
SharedPreferences prefs = context.getSharedPreferences(PREFS_NAME, 0);
String prefix = prefs.getString(PREF_PREFIX_KEY + appWidgetId, null);
if (prefix != null) {
return prefix;
} else {
return context.getString(R.string.appwidget_prefix_default);
}
}
static void deleteTitlePref(Context context, int appWidgetId) {
}
static void loadAllTitlePrefs(Context context, ArrayList<Integer> appWidgetIds,
ArrayList<String> texts) {
}
}
原文：http://our2848884.blog.163.com/blog/static/14685483420115345933319/
