java 版本比较

public class version {

    public static int compareVersion(String version1, String version2) throws Exception {
        if (version1 == null || version2 == null) {
            throw new Exception("compareVersion error:illegal params.");
        }
        String[] versionArray1 = version1.split("\\.");//注意此处为正则匹配，不能用"."；
        String[] versionArray2 = version2.split("\\.");
        int idx = 0;
        int minLength = Math.min(versionArray1.length, versionArray2.length);//取最小长度值
        int diff = 0;
        while (idx < minLength
                && (diff = versionArray1[idx].length() - versionArray2[idx].length()) == 0//先比较长度
                && (diff = versionArray1[idx].compareTo(versionArray2[idx])) == 0) {//再比较字符
            ++idx;
        }
        //如果已经分出大小，则直接返回，如果未分出大小，则再比较位数，有子版本的为大；
        diff = (diff != 0) ? diff : versionArray1.length - versionArray2.length;
        return diff;
    }

    public static void main(String [] args) throws Exception{
        System.out.println(compareVersion("1.2.3", "1.2.3"));
    }
}