在AndroidStudio中，我创建一个新的android项目，创建一个应用程序小部件，并为配置活动选择选项。AndroidStudio现在生成提供者信息xml、清单xml中的decorations和两个java类。一个活动，一个小部件提供商。
这应该是可运行的，但我收到错误：无法识别启动活动：找不到默认活动。启动活动时出错。发射场也显示了一个红十字。
我不明白为什么，因为没有默认的活动。配置活动应该在小部件提供程序开始工作时启动。为此，有一个活动的意图过滤器，带有android.appwidget.action.appwidget_CONFIGURE.
我还在意向过滤器LAUNCHER和DEFAULT中添加了类别。在提供者和活动中。但仍然收到错误消息。
如果我在启动配置中选择"Nothing"并运行应用程序，它只会带来许多错误消息：等待应用程序联机：com.example.desktop_win10myapplication|com.example.dedesktop_win10mmyapplication.test
但是小部件没有安装，也没有运行。我做错了什么？我试用了Intellij和AndroidStudio。
Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.desktop_win10.myapplication" >
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme" >
<receiver android:name=".NewAppWidget" >
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
</intent-filter>
<meta-data
android:name="android.appwidget.provider"
android:resource="@xml/new_app_widget_info" />
</receiver>
<activity android:name=".NewAppWidgetConfigureActivity" >
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" />
</intent-filter>
</activity>
</application>
</manifest>
widget_info.xml:
<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
android:minWidth="40dp"
android:minHeight="40dp"
android:updatePeriodMillis="86400000"
android:previewImage="@drawable/example_appwidget_preview"
android:initialLayout="@layout/new_app_widget"
android:configure="com.example.desktop_win10.myapplication.NewAppWidgetConfigureActivity"
android:resizeMode="horizontal|vertical"
android:widgetCategory="home_screen"
android:initialKeyguardLayout="@layout/new_app_widget">
</appwidget-provider>
还有两个Java类。
第1版：
现在我添加类别Launchher和动作MAIN:
<activity android:name=".NewAppWidgetConfigureActivity" >
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" />
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
如果我启动调试器，有时小部件在小部件存储中，有时不在。
我还看到，在生成的java活动类中有一个名为的finish方法
// If this activity was started with an intent without an app widget ID, finish with an error.
if (mAppWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) {
finish();
return;
}
但如果我删除了这个，它也不起作用。我不明白为什么默认的谷歌示例不起作用。
以下是java类：
活动：
package com.example.desktop_win10.myapplication;
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.view.View;
import android.widget.EditText;
/**
* The configuration screen for the {@link NewAppWidget NewAppWidget} AppWidget.
*/
public class NewAppWidgetConfigureActivity extends Activity {
int mAppWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
EditText mAppWidgetText;
private static final String PREFS_NAME = "com.example.desktop_win10.myapplication.NewAppWidget";
private static final String PREF_PREFIX_KEY = "appwidget_";
public NewAppWidgetConfigureActivity() {
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 the user presses the back button.
setResult(RESULT_CANCELED);
setContentView(R.layout.new_app_widget_configure);
mAppWidgetText = (EditText)findViewById(R.id.appwidget_text);
findViewById(R.id.add_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 this activity was started with an intent without an app widget ID, finish with an error.
if (mAppWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) {
finish();
return;
}
mAppWidgetText.setText(loadTitlePref(NewAppWidgetConfigureActivity.this, mAppWidgetId));
}
View.OnClickListener mOnClickListener = new View.OnClickListener() {
public void onClick(View v) {
final Context context = NewAppWidgetConfigureActivity.this;
// When the button is clicked, store the string locally
String widgetText = mAppWidgetText.getText().toString();
saveTitlePref(context,mAppWidgetId,widgetText);
// It is the responsibility of the configuration activity to update the app widget
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
NewAppWidget.updateAppWidget(context, appWidgetManager, mAppWidgetId);
// 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.apply();
}
// 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 titleValue = prefs.getString(PREF_PREFIX_KEY + appWidgetId, null);
if (titleValue != null) {
return titleValue;
} else {
return context.getString(R.string.appwidget_text);
}
}
static void deleteTitlePref(Context context, int appWidgetId) {
SharedPreferences.Editor prefs = context.getSharedPreferences(PREFS_NAME, 0).edit();
prefs.remove(PREF_PREFIX_KEY + appWidgetId);
prefs.apply();
}
}
和提供商：
package com.example.desktop_win10.myapplication;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.widget.RemoteViews;
/**
* Implementation of App Widget functionality.
* App Widget Configuration implemented in {@link NewAppWidgetConfigureActivity NewAppWidgetConfigureActivity}
*/
public class NewAppWidget extends AppWidgetProvider {
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
// There may be multiple widgets active, so update all of them
for (int appWidgetId : appWidgetIds) {
updateAppWidget(context, appWidgetManager, appWidgetId);
}
}
@Override
public void onDeleted(Context context, int[] appWidgetIds) {
// When the user deletes the widget, delete the preference associated with it.
for (int appWidgetId : appWidgetIds) {
NewAppWidgetConfigureActivity.deleteTitlePref(context, appWidgetId);
}
}
@Override
public void onEnabled(Context context) {
// Enter relevant functionality for when the first widget is created
}
@Override
public void onDisabled(Context context) {
// Enter relevant functionality for when the last widget is disabled
}
static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
int appWidgetId) {
CharSequence widgetText = NewAppWidgetConfigureActivity.loadTitlePref(context, appWidgetId);
// Construct the RemoteViews object
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.new_app_widget);
views.setTextViewText(R.id.appwidget_text, widgetText);
// Instruct the widget manager to update the widget
appWidgetManager.updateAppWidget(appWidgetId, views);
}
}
您添加了：吗
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER" />
正如我所知，如果没有它，安卓将不知道推出哪个活动作为主要活动。