android2.3 api demo 学习系列（1）--apidemo主列表的实现

android最有价值的参考资料莫过于sdk提供的apidemos，现在我们就开始一点一点的学习，本人水平有限，文章中出现错误请您指正。

sdk中得apidemos接近200个，设计到android的各个方面，首先先学习下android的开发人员如何将这200多个demo分类的。

1、首先在AndroidManifest.xml注册activity时附件以下intent-filter 例如

<activity android:name=".app.Animation" android:label="@string/activity_animation">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="com.angie.apidemos.SAMPLE_CODE" />            </intent-filter>        </activity>

2、在values/Strings.xml 声明该activity的label值（这样声明是为了下面的list分类）

<string name="activity_animation">App/Activity/Animation</string>

3、最后在自己的activity里面处理list

@Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);                //获取传递进来的附加信息        Intent intent = getIntent();        String path = intent.getStringExtra("com.angie.apidemos.Path");                if (path == null) {            path = "";        }        //create list        setListAdapter(new SimpleAdapter(this, getData(path),                R.layout.mainlist, new String[] { "image", "title" },                new int[] { R.id.rowImage, R.id.rowTitle }));        getListView().setTextFilterEnabled(true);    }    protected List getData(String prefix) {        List<Map> myData = new ArrayList<Map>();        //获取符合条件的activity  （包含其他应用程序符合条件的activity）         Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);        mainIntent.addCategory(MyApplication.CATEGORY_SAMPLE_CODE);        PackageManager pm = getPackageManager();        List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);        if (null == list)            return myData;        String[] prefixPath;                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);            CharSequence labelSeq = info.loadLabel(pm);             String label = labelSeq != null                    ? labelSeq.toString()                    : info.activityInfo.name;            if (prefix.length() == 0 || label.startsWith(prefix)) {                                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),                            R.drawable.launcher);                } else {                    if (entries.get(nextLabel) == null) {                        addItem(myData, nextLabel, browseIntent(prefix.equals("") ? nextLabel : prefix + "/" + nextLabel),R.drawable.list);                        entries.put(nextLabel, true);                    }                }            }        }        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"));        }    };    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, ApiDemosStudyActivity.class);        result.putExtra("com.angie.apidemos.Path", path);        return result;    }    protected void addItem(List<Map> data, String name, Intent intent, int image) {        Map<String, Object> temp = new HashMap<String, Object>();        temp.put("image", image);        temp.put("title", name);        temp.put("intent", intent);        data.add(temp);    }    @Override    protected void onListItemClick(ListView l, View v, int position, long id) {        Map map = (Map) l.getItemAtPosition(position);        Intent intent = (Intent) map.get("intent");        startActivity(intent);    }

4、上面的代码没有特别难理解的地方，故不再一一注释。其中用到的mainlist定义如下

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"  android:layout_height="wrap_content"  android:gravity="center_vertical"android:orientation="horizontal"><ImageViewandroid:id="@+id/rowImage"android:layout_width="wrap_content"android:layout_height="wrap_content"android:gravity="center_vertical"android:paddingLeft="6dip"android:src="@drawable/list" /><TextViewandroid:id="@+id/rowTitle"android:layout_width="match_parent"android:layout_height="wrap_content"android:textAppearance="?android:attr/textAppearanceLarge"android:gravity="center_vertical"android:paddingLeft="6dip"android:minHeight="?android:attr/listPreferredItemHeight"/></LinearLayout>

注：代码中用到的drawable资源请自行导入，不再赘述。

其中用到的MyApplication类主要是想定义一个CATEGORY_SAMPLE_CODE，你也可以放弃这种方式直接使用intent内部定义的CATEGORY。代码示例如下

public class MyApplication extends Application {public static final String CATEGORY_SAMPLE_CODE = "com.angie.apidemos.SAMPLE_CODE";/* (non-Javadoc) * @see android.app.Application#onCreate() */@Overridepublic void onCreate() {// TODO Auto-generated method stubsuper.onCreate();}}

效果图：

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