Gradle缓存目录文件命名规则

在打开Android Studio项目的时候，会下载项目对应版本的gradle，该版本是在项目根目录下\gradle\wrapper\gradle-wrapper.properties文件中指定的：

下载的gradle文件在Windows电脑上会缓存在C:\Users\xxx(用户名)\.gradle\wrapper\dists\gradle-3.3-all\55gk2rcmfc6p2dg9u9ohc3hw9目录下

那这个目录名55gk2rcmfc6p2dg9u9ohc3hw9是根据什么规则生成的呢？看似没有规律，研究了一下，发现也是按照一定规则生成的，如下：

1.从gradle/wrapper/gradle-wrapper.properties中得到distributionUrl，即https://services.gradle.org/distributions/gradle-3.3-all.zip，注意文件中的\不算

2.对distributionUrl进行MD5运算

3.根据MD5值构造一个uint 128位整数

4.将整数利用base36得到base36的值（取小写）

java代码如下：

 public static String getFileName(String distributionUrl)
    {
        MessageDigest messageDigest = null;
        try
        {
            messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.update(distributionUrl.getBytes());
            String str = new BigInteger(1, messageDigest.digest()).toString(36);
            return str;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }

distributionUrl	base36
https://services.gradle.org/distributions/gradle-4.7-all.zip	4cret0dgl5o3b21weaoncl7ys
https://services.gradle.org/distributions/gradle-4.6-all.zip	bcst21l2brirad8k2ben1letg
https://services.gradle.org/distributions/gradle-4.5.1-all.zip	87kuriyahurjjkki3zii366f2
https://services.gradle.org/distributions/gradle-4.5-all.zip	cg9lyzfg3iwv6fa00os9gcgj4
https://services.gradle.org/distributions/gradle-4.4.1-all.zip	2kpyt0ea6hyxavvt21uml23gd
https://services.gradle.org/distributions/gradle-4.4-all.zip	9br9xq1tocpiv8o6njlyu5op1
https://services.gradle.org/distributions/gradle-4.3.1-all.zip	97nfwr7im082t7xwc6bkwfrg9
https://services.gradle.org/distributions/gradle-4.3-all.zip	2c1rgv6vofd95kl0ugolfeu5r
https://services.gradle.org/distributions/gradle-4.2.1-all.zip	domrskppdhf3wtn5mziw0c2zr
https://services.gradle.org/distributions/gradle-4.2-all.zip	35kgqhc6h01n0g1he8zslvs9l
https://services.gradle.org/distributions/gradle-4.1-all.zip	bzyivzo6n839fup2jbap0tjew
https://services.gradle.org/distributions/gradle-4.0.2-all.zip	680wmhe205zg4atnbsmvvt28p
https://services.gradle.org/distributions/gradle-4.0.1-all.zip	26awvqv6f41r14q9x72t4n0s
https://services.gradle.org/distributions/gradle-4.0-all.zip	ac27o8rbd0ic8ih41or9l32mv
https://services.gradle.org/distributions/gradle-3.5.1-all.zip	42vjebfdws9pjts3l4bouoq0p
https://services.gradle.org/distributions/gradle-3.5-all.zip	exhrs6ca08n232b14ue48lbye
https://services.gradle.org/distributions/gradle-3.4.1-all.zip	c3ib5obfnqr0no9szq6qc17do
https://services.gradle.org/distributions/gradle-3.4-all.zip	4bi7dnjj1pmknw0wphqavp2sz
https://services.gradle.org/distributions/gradle-3.3-all.zip	55gk2rcmfc6p2dg9u9ohc3hw9
https://services.gradle.org/distributions/gradle-3.2-all.zip	97ld1dyml0oep92x4lyn4g235
https://services.gradle.org/distributions/gradle-3.1-all.zip	ejgglywf033yp6s4x8ahmgm74
https://services.gradle.org/distributions/gradle-3.0-all.zip	6v8c6qg2jpi8twyfv2a5s9mii
https://services.gradle.org/distributions/gradle-2.14.1-all.zip	8bnwg5hd3w55iofp58khbp6yv
https://services.gradle.org/distributions/gradle-2.14-all.zip	t7wfomcrmv8dmyii9c9waem8
https://services.gradle.org/distributions/gradle-2.13-all.zip	1b9wlm73elu4cqnbc0rk7r7qn
https://services.gradle.org/distributions/gradle-2.12-all.zip	8ywkdai6puj5z81fume4e7njw
https://services.gradle.org/distributions/gradle-2.11-all.zip	ace7yl0a7udokebb27mt9s3qr
https://services.gradle.org/distributions/gradle-2.10-all.zip	a4w5fzrkeut1ox71xslb49gst