digestutil.java

spring struts hibernate 集成开发的web应用

package com.sc.util;

import java.security.MessageDigest;
import java.io.InputStream;

/**
 * <p>Title: md5加密处理</p>
 *
 * <p>Description: </p>
 *
 * <p>Copyright: Copyright (c) 2006</p>
 *
 * <p>Company: </p>
 *
 * @author 
 * @version 1.0
 */
public class DigestUtil {

  public static String getDigestOfMD5(String strInfo) throws Exception {
    return getDigest(strInfo, "MD5");
  }

  public static String getDigestOfMD5(InputStream in) throws Exception {
    InputStream inArr[] = new InputStream[1];
    inArr[0] = in;
    return getDigest(inArr, "MD5");
  }

  public static String getDigestOfMD5(InputStream[] inArr) throws Exception {
    return getDigest(inArr, "MD5");
  }

  private static String getDigest(String strInfo, String digest) throws
      Exception {
    MessageDigest alga = MessageDigest.getInstance(digest);
    alga.update(strInfo.getBytes());
    byte[] digesta = alga.digest();
    return byte2hex(digesta);
  }

  private static String getDigest(InputStream inArr[], String digest) throws
      Exception {
    MessageDigest alga = MessageDigest.getInstance(digest);

    byte[] b = new byte[4096];
    int i = 0;
    for (int k = 0; k < inArr.length; k++) {
      InputStream in = inArr[k];
      while ( (i = in.read(b)) != -1) {
        alga.update(b, 0, i);
      }
      in.close();
    }
    byte[] digesta = alga.digest();
    return byte2hex(digesta);
  }

  private static String byte2hex(byte[] b) {
    StringBuffer hs = new StringBuffer();
    String stmp = "";
    for (int n = 0; n < b.length; n++) {
      stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
      if (stmp.length() == 1) hs.append("0" + stmp);
      else hs.append(stmp);
    }
    return hs.toString().toLowerCase();
  }
}