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生成主键的工具类
1 public class UNIDGenerate { 2 3 private static final int IP; 4 5 static { 6 int ipadd; 7 try { 8 ipadd = toInt(InetAddress.getLocalHost().getAddress()); 9 } catch (Exception e) { 10 ipadd = 0; 11 } 12 IP = ipadd; 13 } 14 15 private static short counter = (short) 0; 16 17 private static final int JVM = (int) (System.currentTimeMillis() >>> 8); 18 19 private String sep = ""; 20 21 /** 22 * 从java 的虚拟机计算出一个值 Unique across JVMs on this machine (unless they load 23 * this class in the same quater second - very unlikely) 24 */ 25 protected int getJVM() { 26 return JVM; 27 } 28 29 /** 30 * 在一个毫秒单位里的唯一整数值 Unique in a millisecond for this JVM instance (unless 31 * there are > Short.MAX_VALUE instances created in a millisecond) 32 */ 33 protected short getCount() { 34 synchronized (UNIDGenerate.class) { 35 if (counter < 0) 36 counter = 0; 37 return counter++; 38 } 39 } 40 41 /** 42 * 局域网唯一IP地址 Unique in a local network 43 */ 44 protected int getIP() { 45 return IP; 46 } 47 48 /** 49 * Unique down to millisecond 50 */ 51 protected short getHiTime() { 52 return (short) (System.currentTimeMillis() >>> 32); 53 } 54 55 protected int getLoTime() { 56 return (int) System.currentTimeMillis(); 57 } 58 59 protected String format(int intval) { 60 String formatted = Integer.toHexString(intval); 61 StringBuffer buf = new StringBuffer("00000000"); 62 buf.replace(8 - formatted.length(), 8, formatted); 63 return buf.toString(); 64 } 65 66 protected String format(short shortval) { 67 String formatted = Integer.toHexString(shortval); 68 StringBuffer buf = new StringBuffer("0000"); 69 buf.replace(4 - formatted.length(), 4, formatted); 70 return buf.toString(); 71 } 72 73 /** 74 * 返回生成的unid 75 * 76 * @return String-unid值 77 */ 78 public String toString() { 79 StringBuffer sb = new StringBuffer(36).append(format(getIP())).append( 80 sep).append(format(getJVM())).append(sep).append( 81 format(getHiTime())).append(sep).append(format(getLoTime())) 82 .append(sep).append(format(getCount())); 83 MessageDigest md5 = null; 84 try { 85 md5 = MessageDigest.getInstance("MD5"); 86 } catch (NoSuchAlgorithmException e) { 87 return sb.toString().toUpperCase(); 88 } 89 md5.update(sb.toString().getBytes()); 90 byte[] array = md5.digest(); 91 StringBuffer ret = new StringBuffer(); 92 for (int j = 0; j < array.length; ++j) { 93 int b = array[j] & 0xFF; 94 if (b < 0x10) 95 ret.append(‘0‘); 96 ret.append(Integer.toHexString(b)); 97 } 98 return ret.toString().toUpperCase(); 99 } 100 101 /** 102 * 返回生成的unid 103 * 104 * @return String-unid值 105 */ 106 public String getUnid() { 107 return toString(); 108 } 109 110 /** 111 * 判断输入的字符串是否为32位Unid 112 * 113 * @param str 114 * 输入字符串 115 * @return 若是32位Unid,则返回True,否则返回False 116 */ 117 public static boolean isUnid(String str) { 118 if (str.length() == 32 && str.matches("[A-Z0-9]{32}")) { 119 return true; 120 } 121 return false; 122 } 123 124 public static int toInt(byte[] bytes) { 125 int result = 0; 126 for (int i = 0; i < 4; i++) { 127 result = (result << 8) - Byte.MIN_VALUE + (int) bytes[i]; 128 } 129 return result; 130 } 131 }
生成主键的工具类
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