uniqueidentifier | 易学教程

How to choose the id generation strategy when using JPA and Hibernate

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I was going through Id generation section of the Hibernate reference guide and "java persistence with Hibernate" There are quite a few options available with Hibernate and JPA combined. I was looking for a further documentation on how to choose the specific id generation strategy. I am also looking for tipping points. For example, hilo strategy is expected to reduce contention. I am assuming there must be a trade off associated with this choice. I want to be educated about the trade offs. Is there any literature available? The API Doc are very clear on this. All generators implement the

What's a good way to uniquely identify a computer?

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问题 I\'m developing some desktop software for a client to resell. The client wants to restrict the software so that the registration code will be specific to one and only one computer. Besides using the MAC from the network card, does anyone have any other techniques (that work on both Windows and Mac OS X) for uniquely identifying a computer? 回答1: Another solution is to use a licensing technology with a dongle . This is a small device that plugs into USB or another I/O port on the host, and

How to preserve identifierForVendor in ios after uninstalling ios app on device?

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问题 I am developing an iOS app which calls web-service for login and at that time i send login credentials to web server along with vendor identifier (identifierForVendor),to identify device uniquely for those credentials.So user can have only one device and one credential. I got identifierForVendor with NSString *uuid = [[UIDevice currentDevice] identifierForVendor].UUIDString This identifier will then store in database of web server and also in device database.Next time when user opens

Is there a unique Android device ID?

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问题 Do Android devices have a unique ID, and if so, what is a simple way to access it using Java? 回答1: Settings.Secure#ANDROID_ID returns the Android ID as an unique for each user 64-bit hex string. import android.provider.Settings.Secure; private String android_id = Secure.getString(getContext().getContentResolver(), Secure.ANDROID_ID); 回答2: UPDATE : As of recent versions of Android, many of the issues with ANDROID_ID have been resolved, and I believe this approach is no longer necessary. Please

How to create a GUID/UUID in Python

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问题 How do I create a GUID in Python that is platform independent? I hear there is a method using ActivePython on Windows but it\'s Windows only because it uses COM. Is there a method using plain Python? 回答1: The uuid module, in Python 2.5 and up, provides RFC compliant UUID generation. See the module docs and the RFC for details. [source] Docs: Python 2: http://docs.python.org/2/library/uuid.html Python 3: https://docs.python.org/3/library/uuid.html Example (working on 2 and 3): >>> import uuid

Generating a unique machine id

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问题 I need to write a function that generates an id that is unique for a given machine running a Windows OS. Currently, I\'m using WMI to query various hardware parameters and concatenate them together and hash them to derive the unique id. My question is, what are the suggested parameters I should use? Currently, I\'m using a combination of bios\\cpu\\disk data to generate the unique id. And am using the first result if multiple results are there for each metric. However, I ran into an issue

How unique is UUID?

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问题 How safe is it to use UUID to uniquely identify something (I\'m using it for files uploaded to the server)? As I understand it, it is based off random numbers. However, it seems to me that given enough time, it would eventually repeat it self, just by pure chance. Is there a better system or a pattern of some type to alleviate this issue? 回答1: Very safe: the annual risk of a given person being hit by a meteorite is estimated to be one chance in 17 billion, which means the probability is about

PHP: How to generate a random, unique, alphanumeric string?

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问题 How would it be possible to generate a random, unique string using numbers and letters for use in a verify link? Like when you create an account on a website, and it sends you an email with a link, and you have to click that link in order to verify your account...yeah...one of those. How can I generate one of those using PHP? Update: Just remembered about uniqid(). It\'s a PHP function that generates a unique identifier based on the current time in microseconds. I think I\'ll use that. 回答1:

How to get a unique computer identifier in Java (like disk ID or motherboard ID)?

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I'd like to get an id unique to a computer with Java, on Windows, MacOS and, if possible, Linux. It could be a disk UUID, motherboard S/N... Runtime.getRuntime().exec can be used (it is not an applet). Ideas? It is common to use the MAC address is associated with the network card. The address is available in Java 6 through through the following API: Java 6 Docs for Hardware Address I haven't used it in Java, but for other network identification applications it has been helpful. Bartosz Firyn The problem with MAC address is that there can be many network adapters connected to the computer. Most