获取版本号

    public String getVersion(Context context){
        
        PackageManager pm = null;
        
        PackageInfo packageInfo = null;
        
        try {
            pm = context.getPackageManager();
            
            packageInfo = pm.getPackageInfo(context.getPackageName(), 0);
            
            return packageInfo.versionName;
        } catch (NameNotFoundException e) {
            e.printStackTrace();
        }finally{
            packageInfo = null;
            pm = null;
        }
        
        return context.getString(R.string.default_show_version);
    }