android从未安装的apk文件里获取信息(包信息，资源信息)

/**
* 获取未安装的apk信息
*
* @param ctx Context
* @param apkPath apk路径，可以放在SD卡
* @return
*/
public static AppInfoData getApkFileInfo(Context ctx, String apkPath)
{
System.out.println(apkPath);
File apkFile = new File(apkPath);
if (!apkFile.exists() || !apkPath.toLowerCase().endsWith(".apk"))
{
System.out.println("file path is not correct");
return null;
}

AppInfoData appInfoData;
String PATH_PackageParser = "android.content.pm.PackageParser";
String PATH_AssetManager = "android.content.res.AssetManager";
try
{
//反射得到pkgParserCls对象并实例化,有参数
Class<?> pkgParserCls = Class.forName(PATH_PackageParser);
Class<?>[] typeArgs = {String.class};
Constructor<?> pkgParserCt = pkgParserCls.getConstructor(typeArgs);
Object[] valueArgs = {apkPath};
Object pkgParser = pkgParserCt.newInstance(valueArgs);

//从pkgParserCls类得到parsePackage方法
DisplayMetrics metrics = new DisplayMetrics();
metrics.setToDefaults();//这个是与显示有关的, 这边使用默认
typeArgs = new Class<?>[]{File.class,String.class,
DisplayMetrics.class,int.class};
Method pkgParser_parsePackageMtd = pkgParserCls.getDeclaredMethod("parsePackage", typeArgs);

valueArgs=new Object[]{new File(apkPath),apkPath,metrics,0};

//执行pkgParser_parsePackageMtd方法并返回
Object pkgParserPkg = pkgParser_parsePackageMtd.invoke(pkgParser, valueArgs);

//从返回的对象得到名为"applicationInfo"的字段对象
if (pkgParserPkg==null)
{
return null;
}
Field appInfoFld = pkgParserPkg.getClass().getDeclaredField("applicationInfo");

//从对象"pkgParserPkg"得到字段"appInfoFld"的值
if (appInfoFld.get(pkgParserPkg)==null)
{
return null;
}
ApplicationInfo info = (ApplicationInfo) appInfoFld.get(pkgParserPkg);

//反射得到assetMagCls对象并实例化,无参
Class<?> assetMagCls = Class.forName(PATH_AssetManager);
Object assetMag = assetMagCls.newInstance();
//从assetMagCls类得到addAssetPath方法
typeArgs = new Class[1];
typeArgs[0] = String.class;
Method assetMag_addAssetPathMtd = assetMagCls.getDeclaredMethod("addAssetPath", typeArgs);
valueArgs = new Object[1];
valueArgs[0] = apkPath;
//执行assetMag_addAssetPathMtd方法
assetMag_addAssetPathMtd.invoke(assetMag, valueArgs);

//得到Resources对象并实例化,有参数
Resources res = ctx.getResources();
typeArgs = new Class[3];
typeArgs[0] = assetMag.getClass();
typeArgs[1] = res.getDisplayMetrics().getClass();
typeArgs[2] = res.getConfiguration().getClass();
Constructor<Resources> resCt = Resources.class.getConstructor(typeArgs);
valueArgs = new Object[3];
valueArgs[0] = assetMag;
valueArgs[1] = res.getDisplayMetrics();
valueArgs[2] = res.getConfiguration();
//这个是重点
//得到Resource对象后可以有很多用处
res = (Resources) resCt.newInstance(valueArgs);

// 读取apk文件的信息
appInfoData = new AppInfoData();
if (info!=null)
{
if (info.icon != 0)
{
// 图片存在，则读取相关信息
Drawable icon = res.getDrawable(info.icon);// 图标
appInfoData.setAppicon(icon);
}
if (info.labelRes != 0)
{
String neme = (String) res.getText(info.labelRes);// 名字
appInfoData.setAppname(neme);
}else
{
String apkName=apkFile.getName();
appInfoData.setAppname(apkName.substring(0,apkName.lastIndexOf(".")));
}
String pkgName = info.packageName;// 包名
appInfoData.setApppackage(pkgName);
}
else
{
return null;
}
PackageManager pm = ctx.getPackageManager();
PackageInfo packageInfo = pm.getPackageArchiveInfo(apkPath, PackageManager.GET_ACTIVITIES);
if (packageInfo != null)
{
appInfoData.setAppversion(packageInfo.versionName);//版本号
appInfoData.setAppversionCode(packageInfo.versionCode+"");//版本码
}
return appInfoData;
} catch (Exception e)
{
e.printStackTrace();
}
return null;
}