import java.io.UnsupportedEncodingException;import java.security.MessageDigest;import java.util.HashMap;import java.util.Map;import java.util.concurrent.locks.ReentrantLock;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;/** * 简单计算MD5 */public class MD5Utils {    private static final Log               log     = LogFactory.getLog(MD5Utils.class);    private static char[]                  digits  = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c',            'd', 'e', 'f'                         };    private static Map
     
       rDigits = new HashMap
      
       (16);    static {        for (int i = 0; i < digits.length; ++i) {            rDigits.put(digits[i], i);        }    }    private static MD5Utils                me      = new MD5Utils();    private MessageDigest                  mHasher;    private ReentrantLock                  opLock  = new ReentrantLock();    private MD5Utils(){        try {            mHasher = MessageDigest.getInstance("md5");        } catch (Exception e) {            throw new RuntimeException(e);        }    }    public static MD5Utils getInstance() {        return me;    }    public String getMD5String(String content) {        return bytes2string(hash(content));    }    public String getMD5String(byte[] content) {        return bytes2string(hash(content));    }    public byte[] getMD5Bytes(byte[] content) {        return hash(content);    }    /**     * 对字符串进行md5     *      * @param str     * @return md5 byte[16]     */    public byte[] hash(String str) {        opLock.lock();        try {            byte[] bt = mHasher.digest(str.getBytes("UTF-8"));            if (null == bt || bt.length != 16) {                throw new IllegalArgumentException("md5 need");            }            return bt;        } catch (UnsupportedEncodingException e) {            throw new RuntimeException("unsupported utf-8 encoding", e);        } finally {            opLock.unlock();        }    }    /**     * 对二进制数据进行md5     *      * @param str     * @return md5 byte[16]     */    public byte[] hash(byte[] data) {        opLock.lock();        try {            byte[] bt = mHasher.digest(data);            if (null == bt || bt.length != 16) {                throw new IllegalArgumentException("md5 need");            }            return bt;        } finally {            opLock.unlock();        }    }    /**     * 将一个字节数组转化为可见的字符串     *      * @param bt     * @return     */    public String bytes2string(byte[] bt) {        int l = bt.length;        char[] out = new char[l << 1];        for (int i = 0, j = 0; i < l; i++) {            out[j++] = digits[(0xF0 & bt[i]) >>> 4];            out[j++] = digits[0x0F & bt[i]];        }        if (log.isDebugEnabled()) {            log.debug("[hash]" + (new String(out)));        }        return new String(out);    }    /**     * 将字符串转换为bytes     *      * @param str     * @return byte[]     */    public byte[] string2bytes(String str) {        if (null == str) {            throw new IllegalArgumentException("str is null");        }        if (str.length() != 32) {            throw new IllegalArgumentException("str.length() != 32");        }        byte[] data = new byte[16];        char[] chs = str.toCharArray();        for (int i = 0; i < 16; ++i) {            int h = rDigits.get(chs[i * 2]).intValue();            int l = rDigits.get(chs[i * 2 + 1]).intValue();            data[i] = (byte) ((h & 0x0F) << 4 | (l & 0x0F));        }        return data;    }}