简易版JAVA生成固定四位短连接
前言：利用base64与md5，生成定长四位的短连接(不包括域名)
举例：http://Nolog/asdasdasd/asdasda/aqwertyuiopasdfghjklzxcvbnm5132456789
效果：
代码：
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* 短网址的实现，不管多长，都生成四位链接
*
* @author CHX
*
*/
public class ShortURL {
private static String plainUrl = "http://Nolog/asdasdasd/asdasda/aqwertyuiopasdfghjklzxcvbnm5132456789";
private static String[] chars = new String[] { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n",
"o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "0", "1", "2", "3", "4", "5", "6", "7", "8",
"9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T",
"U", "V", "W", "X", "Y", "Z" };
public static void main(String[] args) {
myTestShort(plainUrl, "Nolog");
}
/**
* 首先从URL中获取固定格式后的内容
*
* @param longUrl
* 原url
* @param yuMing
* 域名
*/
public static void myTestShort(String longUrl, String yuMing) {
String regex = "(http://|https://)" + yuMing + "(.*)";
Pattern r = Pattern.compile(regex);
// 现在创建 matcher 对象
Matcher m = r.matcher(longUrl);
if (m.find()) {
String url = m.group(2);
if (url != null) {
// 此处就是生成的四位短连接
System.out.println(m.group(1) + yuMing + "/" + changes(url));
}
}
}
/**
* 编码思路：考虑到base64编码后，url中只有[0-9][a-z][A-Z]这几种字符，所有字符共有26+26+10=62种 对应的映射表为62进制即可
*
* @param value
* @return
*/
public static String changes(String value) {
// 获取base64编码
String stringBase64 = stringBase64(value);
// 去除最后的==(这是base64的特征，最后以==结尾)
stringBase64 = stringBase64.substring(0, stringBase64.length() - 2);
MessageDigest md5 = null;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
// 利用md5生成32位固长字符串
String mid = new String(bytesToHexString(md5.digest(stringBase64.getBytes())));
StringBuilder outChars = new StringBuilder();
for (int i = 0; i < 4; i++) {
//每八个一组
String sTempSubString = mid.substring(i * 8, i * 8 + 8);
// 想办法将此16进制的八个字符数缩减到62以内，所以取余，然后置换为对应的字母数字
outChars.append(chars[(int) (Long.parseLong(sTempSubString, 16) % chars.length)]);
}
return outChars.toString();
}
/**
* 将字符串转换为base64编码
*
* @param text
* 原文
* @return
*/
public static String stringBase64(String text) {
return Base64.getEncoder().encodeToString(text.getBytes());
}
/**
* 将byte转换为16进制的字符串
*
* @param src
* @return
*/
public static String bytesToHexString(byte[] src) {
StringBuilder stringBuilder = new StringBuilder();
if (src == null || src.length <= 0) {
return null;
}
for (int i = 0; i < src.length; i++) {
int v = src[i] & 0xFF;
String hv = Integer.toHexString(v);
if (hv.length() < 2) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
}
return stringBuilder.toString();
}
}