stringutil.java

java的MD5加密的程序

package test; 
import java.security.MessageDigest; 
/** 
 * <p>Title: </p> 
 * <p>Description: </p> 
 * <p>Copyright: Copyright (c) 2003</p> 
 * <p>Company: </p> 
 * @author unascribed 
 * @version 1.0 
 */ 

public class StringUtil { 

  private final static String[] hexDigits = { 
      "0", "1", "2", "3", "4", "5", "6", "7", 
      "8", "9", "a", "b", "c", "d", "e", "f"}; 

  /** 
   * 转换字节数组为16进制字串 
   * @param b 字节数组 
   * @return 16进制字串 
   */ 

  public static String byteArrayToHexString(byte[] b) { 
    StringBuffer resultSb = new StringBuffer(); 
    for (int i = 0; i < b.length; i++) { 
      resultSb.append(byteToHexString(b[i])); 
    } 
    return resultSb.toString(); 
  } 

  private static String byteToHexString(byte b) { 
    int n = b; 
    if (n < 0) 
      n = 256 + n; 
    int d1 = n / 16; 
    int d2 = n % 16; 
    return hexDigits[d1] + hexDigits[d2]; 
  } 

  public static String MD5Encode(String origin) { 
    String resultString = null; 

    try { 
      resultString=new String(origin); 
      MessageDigest md = MessageDigest.getInstance("MD5"); 
      resultString=byteArrayToHexString(md.digest(resultString.getBytes())); 
    } 
    catch (Exception ex) { 

    } 
    return resultString; 
  } 

  public static void main(String[] args){ 
    System.err.println(MD5Encode("a")); 
  } 
}