Android 2.2 API demos -- ApiDemos.java

<activity android:name="ApiDemos"><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>

/** 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**      [url]http://www.apache.org/licenses/LICENSE-2.0[/url]** 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;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;/** 主要是通过对Activity的label信息进行分析，从而将Activity进行分类并通过ListView显示出来。* 例如<activity android:name=".app.HelloWorld" android:label="@string/activity_hello_world">的label为* App/Activity/Hello World，程序运行的结果是一级目录含有App选项，点击App出现的二级目录含有Activity选项，* 点击Activity出现的三级目录含有Hello World选项，点击Hello World会出现Hello World这个Activity运行的结果*/
public class ApiDemos extends ListActivity {@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);Intent intent = getIntent();/** 当程序启动要显示一级目录（App, Content, ...）时，Intent对象里绑定的附加信息path为空* 当点击一级目录选项进入二级目录（例如App下的Activity, Alarm, ...）时，path就不为空了（例如为App）*/String path = intent.getStringExtra("com.example.android.apis.Path");if (path == null) {path = "";}// 通过adapter为当前ListActivity传递数据setListAdapter(new SimpleAdapter(this, getData(path),android.R.layout.simple_list_item_1, new String[] { "title" },new int[] { android.R.id.text1 }));// 允许当前ListView可以根据用户输入的值进行过滤getListView().setTextFilterEnabled(true);}/** 获取应用列表，包括一级目录，二级目录，等等*/protected List getData(String prefix) {List<Map> myData = new ArrayList<Map>();/** 获取在AndroidManifest.xml文件中的Intent Filter里配置了* Intent.ACTION_MAIN和Intent.CATEGORY_SAMPLE_CODE的所有Activity*/Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);mainIntent.addCategory(Intent.CATEGORY_SAMPLE_CODE);PackageManager pm = getPackageManager();List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);if (null == list)return myData;String[] prefixPath;// 当要显示一级目录时，prefix为空字符串；当点击App进入要显示二级目录时，prefix为App；if (prefix.equals("")) {prefixPath = null;} else {prefixPath = prefix.split("/");}int len = list.size();Map<String, Boolean> entries = new HashMap<String, Boolean>();for (int i = 0; i < len; i++) {ResolveInfo info = list.get(i);// 获取Activity的label信息，例如App/Activity/Hello WorldCharSequence labelSeq = info.loadLabel(pm);String label = labelSeq != null? labelSeq.toString(): info.activityInfo.name;if (prefix.length() == 0 || label.startsWith(prefix)) {// 例如labelPath = [App, Activity, Hello World]String[] labelPath = label.split("/");// 例如要显示一级目录时nextLabel = "App"，要显示二级目录时，nextLabel = "Activity"String nextLabel = prefixPath == null ? labelPath[0] : labelPath[prefixPath.length];// 当要显示的label为Activity而非目录时，需要为label绑定跳转到相关Activity的Intentif ((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);}}}}// 排序Collections.sort(myData, sDisplayNameComparator);return myData;}private final static Comparator<Map> sDisplayNameComparator = new Comparator<Map>() {private final Collator   collator = Collator.getInstance();public int compare(Map map1, Map map2) {return collator.compare(map1.get("title"), map2.get("title"));}};/** 为label绑定跳转到相关Activity的Intent*/protected Intent activityIntent(String pkg, String componentName) {Intent result = new Intent();result.setClassName(pkg, componentName);return result;}/** 为label绑定跳转到当前Activity的Intent，附加信息path为当前目录* 例如为Activity这个label绑定的Intent中附加值为App/Activity*/protected Intent browseIntent(String path) {Intent result = new Intent();result.setClass(this, ApiDemos.class);result.putExtra("com.example.android.apis.Path", path);return result;}/** 将符合条件的选项加入List中*/protected void addItem(List<Map> data, String name, Intent intent) {Map<String, Object> temp = new HashMap<String, Object>();temp.put("title", name);temp.put("intent", intent);data.add(temp);}@Overrideprotected void onListItemClick(ListView l, View v, int position, long id) {Map map = (Map) l.getItemAtPosition(position);Intent intent = (Intent) map.get("intent");startActivity(intent);}}

3. 主要流程为（以App/Activity/Hello World为例）：3. 主要流程为（以App/Activity/Hello World为例）：

4. 主要技巧在于将所有的Activity的类别信息配置在AndroidManifest.xml中，充分发挥了配置文件的优势。