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"));
     }
 }