Android 获取包名，版本信息及VersionName名称

private String getAppInfo() {
         try {
             String pkName = this.getPackageName();
             String versionName = this.getPackageManager().getPackageInfo(
                     pkName, 0).versionName;
             int versionCode = this.getPackageManager()
                     .getPackageInfo(pkName, 0).versionCode;
             return pkName + "   " + versionName + "  " + versionCode;
         } catch (Exception e) {
         }
         return null;
     }