import java.security.MessageDigest;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;public class MD5 {    private final Log logger = LogFactory.getLog(MD5.class);    private String inStr;    private MessageDigest md5;    /* 下面是构造函数 */    public MD5(String inStr) {        this.inStr = inStr;        try {            this.md5 = MessageDigest.getInstance("MD5");        } catch (Exception e) {            logger.fatal("", e);        }    }    /* 下面是关键的md5算法 */    public String compute() {        char[] charArray = this.inStr.toCharArray();        byte[] byteArray = new byte[charArray.length];        for (int i = 0; i < charArray.length; i++)            byteArray[i] = (byte) charArray[i];        byte[] md5Bytes = this.md5.digest(byteArray);        StringBuffer hexValue = new StringBuffer();        for (int i = 0; i < md5Bytes.length; i++) {            int val = ((int) md5Bytes[i]) & 0xff;            if (val < 16)                hexValue.append("0");            hexValue.append(Integer.toHexString(val));        }        return hexValue.toString();    }    /* 下面是关键的md5算法 */    public String computeWithUTF8() {        try {            byte[] btInput = this.inStr.getBytes("UTF-8"); // 必须制定utf-8字符集。            MessageDigest mdInst = MessageDigest.getInstance("MD5");            mdInst.update(btInput);            byte[] md = mdInst.digest();            StringBuffer sb = new StringBuffer();            for (int i = 0; i < md.length; i++) {                int val = ((int) md[i]) & 0xff;                if (val < 16) {                    sb.append("0");                }                sb.append(Integer.toHexString(val));            }            return sb.toString();        } catch (Exception e) {            return null;        }    }}