一直很想弄清楚好多應用中是如何實現換皮膚這項功能的，花了下午點時間，查了下資料也實現了個切換主題的Demo;

首先要感謝下這位大哥,參閱了下他寫的文件 http://www.eoeandroid.com/forum-viewthread-tid-31756-highlight-%E7%9A%AE%E8%82%A4.html

好了，廢話不多說了，該切換主題的demo里面一共實現了兩個功能，其一，搜索已經安裝的皮膚，其二，應用安裝的皮膚。

主項目包名為org.leepood.skindemo,主題項目的包名為org.leepood.skin.blue,org.leepood.skin.red,等等，只要前綴是org.leepood.skin.就行。

首先是查找已安裝主題的代碼:

    package org.leepood.skindemo;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.Resources;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.ContextMenu;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View.OnCreateContextMenuListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.AdapterContextMenuInfo;

public class Main extends Activity implements SharedPreferences.OnSharedPreferenceChangeListener{

	private ListView listview;
	private Context c;
	private Handler mHandler;
	private ProgressDialog pDialog;
	private SkinAdapter adapter;
	private SharedPreferences sp;
	static final int MESSAGE_SEARCHED_SKIN=0;
	static final int MESSAGE_SEARCHING_SKIN=MESSAGE_SEARCHED_SKIN+1;
	static final int MESSAGE_SEARCHED_SKIN_FOR_NONTHING=MESSAGE_SEARCHING_SKIN+1;

	@Override
	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		init();
		pDialog.show();
		new Thread(serachSkin).start();

	}

	private void init()
	{

		c=this;
		mHandler=new Handler(){

			@Override
			public void handleMessage(Message msg) {
				switch(msg.what)
				{
				case MESSAGE_SEARCHED_SKIN:
					ArrayList
 skins=(ArrayList
) msg.obj;//獲取skins
					adapter=new SkinAdapter(c, skins);
					listview.setAdapter(adapter);
					Toast.makeText(c, "查找到已經安裝的皮膚", 1).show();
					pDialog.dismiss();
					break;
				case MESSAGE_SEARCHED_SKIN_FOR_NONTHING:
					Toast.makeText(c, "未查找到任何皮膚", 1).show();
					pDialog.dismiss();
				}
			}

		};
		sp=this.getSharedPreferences("config",Context.MODE_WORLD_WRITEABLE);
		sp.registerOnSharedPreferenceChangeListener(this);

		listview=(ListView) findViewById(R.id.list);
		listview.setItemsCanFocus(false);
		listview.setChoiceMode(ListView.CHOICE_MODE_SINGLE);

		pDialog=new ProgressDialog(this);
		pDialog.setMessage("正在查找已經安裝的皮膚");

		listview.setOnCreateContextMenuListener(new OnCreateContextMenuListener() {

			public void onCreateContextMenu(ContextMenu menu, View v,
					ContextMenuInfo menuInfo) {
				menu.add("使用該主題");

			}
		});

	}

	private Runnable serachSkin =new Runnable(){

		public void run() {
			PackageManager manager=c.getPackageManager();
			List
 packages=manager.getInstalledPackages(PackageManager.PERMISSION_GRANTED);

			ArrayList
 skins=new ArrayList
();
			for(PackageInfo info:packages)
			{
				//System.out.println(info.packageName);
				if(info.packageName.startsWith("org.leepood.skin."))
				{
					skins.add(info);
				}
			}
			if(skins.size()>0)
			{
				Message msg=mHandler.obtainMessage();
				msg.obj=skins;
				msg.what=MESSAGE_SEARCHED_SKIN;
				mHandler.sendMessage(msg);
			}
			else
			{
				mHandler.sendEmptyMessage(MESSAGE_SEARCHED_SKIN_FOR_NONTHING);
			}

		}

	};
	private class SkinAdapter extends BaseAdapter
	{

		LayoutInflater mInflater;
		ArrayList
 datas;
		PackageManager manager;
		public SkinAdapter(Context c,ArrayList
 datas)
		{

			this.datas=datas;
			 mInflater=LayoutInflater.from(c);
			 manager=c.getPackageManager();
		}

		public int getCount() {

			return datas.size();
		}

		public Object getItem(int position) {

			return datas.get(position);
		}

		public long getItemId(int position) {

			return 0;
		}

		public View getView(int position, View convertView, ViewGroup parent) {

			if(convertView==null)
			{
				convertView=mInflater.inflate(R.layout.skin_item, null);
			}
			ImageView icon=(ImageView) convertView.findViewById(R.id.skin_icon);
			TextView  skin_name=(TextView) convertView.findViewById(R.id.skin_name);
			PackageInfo info=datas.get(position);
			icon.setImageDrawable(info.applicationInfo.loadIcon(manager));
			skin_name.setText(info.applicationInfo.loadLabel(manager));
			return convertView;
		}

	}

	public void onThemeChanged(String newThemePackageName) {
		try {

			Context themeContext=this.createPackageContext(newThemePackageName, CONTEXT_IGNORE_SECURITY);
			Resources res=themeContext.getResources();
			setControlsStyle(res);

		} catch (NameNotFoundException e) {

			e.printStackTrace();
		}

	}

	private void setControlsStyle(Resources res)
	{
		listview.setBackgroundColor(res.getColor(R.color.ListView_bg));

	}

	@Override
	public boolean onContextItemSelected(MenuItem item) {
		AdapterContextMenuInfo menuInfo=(AdapterContextMenuInfo)item.getMenuInfo();
		PackageInfo info=(PackageInfo) adapter.getItem(menuInfo.position);

		sp.edit().putString("themePackage", info.packageName).commit();
		return super.onContextItemSelected(item);
	}

	public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
			String key) {
		System.out.println("themeChange");
		onThemeChanged(sharedPreferences.getString(key, ""));

	}

}
  

這段代碼的含義就是去查找系統中安裝的包名，若以org.leepood.skin.開頭則說明該包為主題包,將其加入listview中顯示出來。代碼中使用了多線程避免時間過長堵塞UI。程序將當前主題配置保存在SharedPreference中,為SharedPreference注冊了一個監聽函數，當其值發生改變時自動調用新的樣式。當然，這只是個demo而已,一開始加載Activity沒有去讀取主題，這個可以由大家自己去實現。
最后貼張圖片:




Android實現主題切換機制2
昨天花了點時間實現了主題的切換，但是里面還是不夠靈活，回去想了想可以用繼承和回調函數來進一步靈活更改主題，現在記錄下我的實現辦法
首先一個自定義類ThemeActivity繼承自Activity，這個類是以后所有Activity的父類，在這個類里面定義了一個接口

public interface OnThemeChangedListener
{
public void onChanged(String newThemePackageName);

}
接下來，首先是要給ThemeActivity注冊一個主題切換的listener,代碼如下:

public void setOnThemeChangedListener(OnThemeChangedListener listener)
{
this.listener=listener;
}
然后就是注冊一個SharedPreference來監聽xml的變化，當發生改變的時候自動去調用listener.onChanged方法，將新的主題包名傳遞過去，代碼如下:

public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
String key) {
if(key.equals("themePackage"))
{
listener.onChanged(sp.getString("themePackage", ""));
}

}
接著在繼承于ThemeActivity的子類里面首先是setOnThemeChangedListener.接著用一個匿名內部類搞定。好啦，代碼可以見附件啦

Android中實現應用切換主題機制