在Java ME/J2ME中生成一个随机的十六进制字符串(长度为50) [英] Generating a random hex string (of length 50) in Java ME/J2ME

问题描述

我的应用程序需要生成一个十六进制字符串以用作会话ID. Java的SecureRandom似乎不起作用("java/lang/NoClassDefFoundError:java/security/SecureRandom:无法在系统包中创建类")

My app needs to generate a hex string to use as a session ID. Java's SecureRandom doesn't seem to be working ("java/lang/NoClassDefFoundError: java/security/SecureRandom: Cannot create class in system package")

我想做这样的事情:

byte[]  resBuf = new byte[50];
new Random().nextBytes(resBuf);
String  resStr = new String(Hex.encode(resBuf));

但是由于某些奇怪的原因，方法nextBytes(byte[] bytes)不可用.

But the method nextBytes(byte[] bytes) isn't available for some strange reason.

有人可以在Java ME/J2ME中生成随机十六进制数吗?

Does anyone have a means of generating a random hex number in Java ME/J2ME?

非常感谢.

当使用Bouncy Castle lcrypto-j2me-145(而不是lcrypto-j2me-147)时，上述生成器似乎可以正常工作.

The above generator seems to work when using Bouncy Castle lcrypto-j2me-145 (but not lcrypto-j2me-147).

推荐答案

JavaME是JavaSE的子集，因此台式机版本中的许多类和方法不可用.

JavaME is a subset of JavaSE, so many classes and methods in the desktop version are not available.

看起来您正在尝试获取给定长度的随机字符串.您可以执行以下操作:

Looks like you are trying to get a random string of a given length. You can do something like this:

    private String getRandomHexString(int numchars){
        Random r = new Random();
        StringBuffer sb = new StringBuffer();
        while(sb.length() < numchars){
            sb.append(Integer.toHexString(r.nextInt()));
        }

        return sb.toString().substring(0, numchars);
    }

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