通过官网的一个例子来看Activity的分组管理

/*
* Copyright (C) 2011 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.supportv4;

import android.app.ListActivity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.view.View;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import java.text.Collator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Support4Demos extends ListActivity {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

Intent intent = getIntent();
String path = intent.getStringExtra("com.example.android.apis.Path");

if (path == null) {
path = "";
}

setListAdapter(new SimpleAdapter(this, getData(path),
android.R.layout.simple_list_item_1, new String[] { "title" },
new int[] { android.R.id.text1 }));
getListView().setTextFilterEnabled(true);
}

protected List<Map<String, Object>> getData(String prefix) {
List<Map<String, Object>> myData = new ArrayList<Map<String, Object>>();

Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory("com.example.android.supportv4.SUPPORT4_SAMPLE_CODE");

PackageManager pm = getPackageManager();
List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);

if (null == list)
return myData;

String[] prefixPath;
String prefixWithSlash = prefix;

if (prefix.equals("")) {
prefixPath = null;
} else {
prefixPath = prefix.split("/");
prefixWithSlash = prefix + "/";
}

int len = list.size();

Map<String, Boolean> entries = new HashMap<String, Boolean>();

for (int i = 0; i < len; i++) {
ResolveInfo info = list.get(i);
CharSequence labelSeq = info.loadLabel(pm);
String label = labelSeq != null
? labelSeq.toString()
: info.activityInfo.name;

if (prefixWithSlash.length() == 0 || label.startsWith(prefixWithSlash)) {

String[] labelPath = label.split("/");

String nextLabel = prefixPath == null ? labelPath[0] : labelPath[prefixPath.length];

if ((prefixPath != null ? prefixPath.length : 0) == labelPath.length - 1) {
addItem(myData, nextLabel, activityIntent(
info.activityInfo.applicationInfo.packageName,
info.activityInfo.name));
} else {
if (entries.get(nextLabel) == null) {
addItem(myData, nextLabel, browseIntent(prefix.equals("") ? nextLabel : prefix + "/" + nextLabel));
entries.put(nextLabel, true);
}
}
}
}

Collections.sort(myData, sDisplayNameComparator);

return myData;
}

private final static Comparator<Map<String, Object>> sDisplayNameComparator =
new Comparator<Map<String, Object>>() {
private final Collator   collator = Collator.getInstance();

public int compare(Map<String, Object> map1, Map<String, Object> map2) {
return collator.compare(map1.get("title"), map2.get("title"));
}
};

protected Intent activityIntent(String pkg, String componentName) {
Intent result = new Intent();
result.setClassName(pkg, componentName);
return result;
}

protected Intent browseIntent(String path) {
Intent result = new Intent();
result.setClass(this, Support4Demos.class);
result.putExtra("com.example.android.apis.Path", path);
return result;
}

protected void addItem(List<Map<String, Object>> data, String name, Intent intent) {
Map<String, Object> temp = new HashMap<String, Object>();
temp.put("title", name);
temp.put("intent", intent);
data.add(temp);
}

@Override
@SuppressWarnings("unchecked")
protected void onListItemClick(ListView l, View v, int position, long id) {
Map<String, Object> map = (Map<String, Object>)l.getItemAtPosition(position);

Intent intent = (Intent) map.get("intent");
startActivity(intent);
}
}

这里的关键在于下面这几行代码

Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory("com.example.android.supportv4.SUPPORT4_SAMPLE_CODE");

PackageManager pm = getPackageManager();
List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);

是把在清单文件AndroidManifest.xml注册category类别为com.example.android.supportv4.SUPPORT4_SAMPLE_CODE的Activity找出来，当然我们也可以自定义一些自己的类别

本例的清单文件如下：

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2007 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.
-->

<!-- Declare the contents of this Android application.  The namespace
attribute brings in the Android platform namespace, and the package
supplies a unique name for the application.  When writing your
own application, the package name must be changed from "com.example.*"
to come from a domain that you own or have control over. -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.supportv4">

<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />

<uses-sdk android:minSdkVersion="17" android:targetSdkVersion="22" />

<!-- The smallest screen this app works on is a phone.  The app will
scale its UI to larger screens but doesn't make good use of them
so allow the compatibility mode button to be shown (mostly because
this is just convenient for testing). -->
<supports-screens android:requiresSmallestWidthDp="320"
android:compatibleWidthLimitDp="480" />

<application android:label="@string/activity_sample_code"
android:icon="@drawable/app_sample_code"
android:hardwareAccelerated="true"
android:supportsRtl="true">

<activity android:name="Support4Demos">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

<activity android:name=".app.SendResult"
android:theme="@style/ThemeDialogWhenLarge">
</activity>

<!-- Fragment Support Samples -->

<activity android:name=".app.FragmentAlertDialogSupport"
android:label="@string/fragment_alert_dialog_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentArgumentsSupport"
android:label="@string/fragment_arguments_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentCustomAnimationSupport"
android:label="@string/fragment_custom_animation_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentHideShowSupport"
android:label="@string/fragment_hide_show_support"
android:windowSoftInputMode="stateUnchanged">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentContextMenuSupport"
android:label="@string/fragment_context_menu_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentDialogSupport"
android:label="@string/fragment_dialog_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentDialogOrActivitySupport"
android:label="@string/fragment_dialog_or_activity_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentLayoutSupport"
android:label="@string/fragment_layout_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentListArraySupport"
android:label="@string/fragment_list_array_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentLayoutSupport$DetailsActivity" />

<activity android:name=".app.FragmentMenuSupport"
android:label="@string/fragment_menu_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentNestingTabsSupport"
android:label="@string/fragment_nesting_tabs_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentRetainInstanceSupport"
android:label="@string/fragment_retain_instance_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentReceiveResultSupport"
android:label="@string/fragment_receive_result_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentStackSupport"
android:label="@string/fragment_stack_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentTabs"
android:label="@string/fragment_tabs">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentTabsPager"
android:label="@string/fragment_tabs_pager">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentPagerSupport"
android:label="@string/fragment_pager_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.FragmentStatePagerSupport"
android:label="@string/fragment_state_pager_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.LoaderCursorSupport"
android:label="@string/loader_cursor_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.LoaderRetainedSupport"
android:label="@string/loader_retained_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.LoaderCustomSupport"
android:label="@string/loader_custom_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.LoaderThrottleSupport"
android:label="@string/loader_throttle_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>
<provider android:name=".app.LoaderThrottleSupport$SimpleProvider"
android:authorities="com.example.android.apis.supportv4.app.LoaderThrottle" />

<activity android:name=".content.LocalServiceBroadcaster"
android:label="@string/local_service_broadcaster">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>
<service android:name=".content.LocalServiceBroadcaster$LocalService"
android:stopWithTask="true" />

<activity android:name=".content.SimpleWakefulController"
android:label="@string/simple_wakeful_controller">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<receiver android:name=".content.SimpleWakefulReceiver" />
<service android:name=".content.SimpleWakefulService" />

<activity android:name=".accessibility.AccessibilityManagerSupportActivity"
android:label="@string/accessibility_manager_title">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".accessibility.AccessibilityDelegateSupportActivity"
android:label="@string/accessibility_delegate_title">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.SharingSupport"
android:label="@string/sharing_support_title">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.SharingReceiverSupport"
android:label="@string/sharing_receiver_title">
<intent-filter>
<action android:name="android.intent.action.SEND" />
<action android:name="android.intent.action.SEND_MULTIPLE" />
<data android:mimeType="text/plain" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>

<activity android:name=".text.BidiFormatterSupport"
android:label="@string/bidiformatter_support_title">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".widget.DrawerLayoutActivity"
android:label="@string/drawer_layout_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".widget.SwipeRefreshLayoutActivity"
android:label="@string/swipe"
android:theme="@style/ThemeHoloLight">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".widget.ContentLoadingProgressBarActivity"
android:label="@string/content_loading_progress_bar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".widget.SlidingPaneLayoutActivity"
android:label="@string/sliding_pane_layout_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".widget.ExploreByTouchHelperActivity"
android:label="@string/explore_by_touch_helper_support">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<provider android:authorities="com.example.supportv4.content.sharingsupportprovider"
android:name=".content.SharingSupportProvider" />

<!-- FileProvider Example -->

<activity android:name=".content.FileProviderExample"
android:label="@string/file_provider_example">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".widget.NestedScrollActivity"
android:label="@string/nested_scroll">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".graphics.RoundedBitmapDrawableActivity"
android:label="Graphics/RoundedBitmapDrawable">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".graphics.DrawableCompatActivity"
android:label="Graphics/DrawableCompat">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.example.android.supportv4.my_files"
android:grantUriPermissions="true"
android:exported="false">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/my_paths" />
</provider>

<activity android:name=".media.TransportControllerActivity"
android:label="@string/sample_transport_controller_activity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="com.example.android.supportv4.SUPPORT4_SAMPLE_CODE" />
</intent-filter>
</activity>

</application>
</manifest>