这是获取apk包的签名信息 private String getSign(Context context) {   PackageManager pm = context.getPackageManager();   List<PackageInfo> apps = pm.getInstalledPackages(PackageManager.GET_SIGNATURES);   Iterator<PackageInfo> iter = apps.iterator();   while(iter.hasNext()) {        PackageInfo packageinfo = iter.next();        String packageName = packageinfo.packageName;        return packageinfo.signatures[0].toCharsString();        if (packageName.equals(instance.getPackageName())) {           MediaApplication.logD(DownloadApk.class, packageinfo.signatures[0].toCharsString());           return packageinfo.signatures[0].toCharsString();        } }   return null; }