枚举所有的activity.

package com.huaqin.smile;

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;

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

/* action/category */

public class WatchDogActivity extends ListActivity {

    String[] categories = new String[] { Intent.CATEGORY_DEFAULT,
            Intent.CATEGORY_BROWSABLE, Intent.CATEGORY_TAB,
            Intent.CATEGORY_ALTERNATIVE, Intent.CATEGORY_SELECTED_ALTERNATIVE,
            Intent.CATEGORY_LAUNCHER, Intent.CATEGORY_INFO,
            Intent.CATEGORY_HOME, Intent.CATEGORY_PREFERENCE,
            Intent.CATEGORY_TEST, Intent.CATEGORY_CAR_DOCK,
            Intent.CATEGORY_DESK_DOCK, Intent.CATEGORY_CAR_MODE };

    String[] actions = new String[]  {
            Intent.ACTION_MAIN,
            Intent.ACTION_VIEW,
            Intent.ACTION_ATTACH_DATA,
            Intent.ACTION_EDIT,
            Intent.ACTION_PICK,
            Intent.ACTION_CHOOSER,
            Intent.ACTION_GET_CONTENT,
            Intent.ACTION_DIAL,
            Intent.ACTION_CALL,
            Intent.ACTION_SEND,
            Intent.ACTION_SENDTO,
            Intent.ACTION_ANSWER,
            Intent.ACTION_INSERT,
            Intent.ACTION_DELETE,
            Intent.ACTION_RUN,
            Intent.ACTION_SYNC,
            Intent.ACTION_PICK_ACTIVITY,
            Intent.ACTION_SEARCH,
            Intent.ACTION_WEB_SEARCH,
            Intent.ACTION_FACTORY_TEST
    };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = getIntent();
        String path = intent.getStringExtra("com.huaqin.CustomerCare.Path");

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

        String action = null;
        String category = null;

        if (path.indexOf('@') == -1) {
            setListAdapter(new SimpleAdapter(this, getCategory(path),
                    android.R.layout.simple_list_item_1, new String[] { "title" },
                    new int[] { android.R.id.text1 }));
           getListView().setTextFilterEnabled(true);
            return;
        }

        action = path.substring(0, path.indexOf('@'));
        category = path.substring(path.indexOf('@') + 1);

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

    private List getCategory(String action) {

        List<Map> myData = new ArrayList<Map>();

        for (String category: categories) {
            String label = category.substring(category.lastIndexOf('.') + 1);
            if (!isCategoryEmpty(action, category))
                addItem(myData, label, browseIntent(action + "@" + category));
        }

        return myData;
    }

    private List getActions() {
        List<Map> myData = new ArrayList<Map>();

        for (String action: actions) {
            String label = action.substring(action.lastIndexOf('.') + 1);
            if (!isActiomEmpty(action))
                addItem(myData, label, browseIntent(action));
        }

        return myData;
    }

    protected boolean isActiomEmpty(String action) {
        for (String category: categories) {
            if (!isCategoryEmpty(action, category))
                return false;
        }
        return true;
    }

    protected boolean isCategoryEmpty(String action, String category) {
        Intent mainIntent = new Intent(action, null);
        mainIntent.addCategory(category);

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

        if (null == list)
            return true;

        return list.size() == 0;
    }

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

        Intent mainIntent = new Intent(action, null);
        mainIntent.addCategory(category);

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

        if (null == list)
            return myData;

        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;

            addItem(myData, label, activityIntent(
                    info.activityInfo.applicationInfo.packageName,
                    info.activityInfo.name));
        }

        Collections.sort(myData, sDisplayNameComparator);

        return myData;
    }

    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, WatchDogActivity.class);
        result.putExtra("com.huaqin.CustomerCare.Path", path);
        return result;
    }

    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 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);
    }

    @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);
    }
}