private String getVersionName() throws Exception

{

        // 获取packagemanager的实例

        PackageManager packageManager = getPackageManager();

        // getPackageName()是你当前类的包名，0代表是获取版本信息

        PackageInfo packInfo = packageManager.getPackageInfo(getPackageName(),0);

        String version = packInfo.versionName;

        return version;

}