问在Java中比较版本字符串的有效方法

EN

/**
 * Compares two version strings. 
 * 
 * Use this instead of String.compareTo() for a non-lexicographical 
 * comparison that works for version strings. e.g. "1.10".compareTo("1.6").
 * 
 * @param v1 a string of alpha numerals separated by decimal points. 
 * @param v2 a string of alpha numerals separated by decimal points.
 * @return The result is 1 if v1 is greater than v2. 
 *         The result is 2 if v2 is greater than v1. 
 *         The result is -1 if the version format is unrecognized. 
 *         The result is zero if the strings are equal.
 */

public int VersionCompare(String v1,String v2)
{
    int v1Len=StringUtils.countMatches(v1,".");
    int v2Len=StringUtils.countMatches(v2,".");

    if(v1Len!=v2Len)
    {
        int count=Math.abs(v1Len-v2Len);
        if(v1Len>v2Len)
            for(int i=1;i<=count;i++)
                v2+=".0";
        else
            for(int i=1;i<=count;i++)
                v1+=".0";
    }

    if(v1.equals(v2))
        return 0;

    String[] v1Str=StringUtils.split(v1, ".");
    String[] v2Str=StringUtils.split(v2, ".");
    for(int i=0;i<v1Str.length;i++)
    {
        String str1="",str2="";
        for (char c : v1Str[i].toCharArray()) {
            if(Character.isLetter(c))
            {
                int u=c-'a'+1;
                if(u<10)
                    str1+=String.valueOf("0"+u);
                else
                    str1+=String.valueOf(u);
            }
            else
                str1+=String.valueOf(c);
        }            
        for (char c : v2Str[i].toCharArray()) {
            if(Character.isLetter(c))
            {
                int u=c-'a'+1;
                if(u<10)
                    str2+=String.valueOf("0"+u);
                else
                    str2+=String.valueOf(u);
            }
            else
                str2+=String.valueOf(c);
        }
        v1Str[i]="1"+str1;
        v2Str[i]="1"+str2;

            int num1=Integer.parseInt(v1Str[i]);
            int num2=Integer.parseInt(v2Str[i]);

            if(num1!=num2)
            {
                if(num1>num2)
                    return 1;
                else
                    return 2;
            }
    }
    return -1;
}    

public static int versionCompare(String str1, String str2) {
    try ( Scanner s1 = new Scanner(str1);
          Scanner s2 = new Scanner(str2);) {
        s1.useDelimiter("\\.");
        s2.useDelimiter("\\.");

        while (s1.hasNextInt() && s2.hasNextInt()) {
            int v1 = s1.nextInt();
            int v2 = s2.nextInt();
            if (v1 < v2) {
                return -1;
            } else if (v1 > v2) {
                return 1;
            }
        }

        if (s1.hasNextInt() && s1.nextInt() != 0)
            return 1; //str1 has an additional lower-level version number
        if (s2.hasNextInt() && s2.nextInt() != 0)
            return -1; //str2 has an additional lower-level version 

        return 0;
    } // end of try-with-resources
}

public static int compareVersions(String v1, String v2) {
    String[] components1 = v1.split("\\.");
    String[] components2 = v2.split("\\.");
    int length = Math.min(components1.length, components2.length);
    for(int i = 0; i < length; i++) {
        int result = new Integer(components1[i]).compareTo(Integer.parseInt(components2[i]));
        if(result != 0) {
            return result;
        }
    }
    return Integer.compare(components1.length, components2.length);
}