常用的java编程工具类

/**
* 对象转字节(序列化)
*
* @param obj
* @return
*/
public static byte[] objectToByte(Object obj) {
byte[] bytes = null;
ByteArrayOutputStream bo = null;
ObjectOutputStream oo = null;
try {
bo = new ByteArrayOutputStream();
oo = new ObjectOutputStream(bo);
oo.writeObject(obj);
bytes = bo.toByteArray();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (bo != null)
bo.close();
if (oo != null)
oo.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return bytes;
}

/**
 * 字节转对象（反序列化）
 * 
 * @param bytes
 * @return
 */
public static Object byteToObject(byte[] bytes) {
    Object obj = null;
    ByteArrayInputStream bi = null;
    ObjectInputStream oi = null;
    try {
        bi = new ByteArrayInputStream(bytes);
        oi = new ObjectInputStream(bi);

        obj = oi.readObject();

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (bi != null)
                bi.close();
            if (oi != null)
                oi.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return obj;
}

/**
 * 判断是否为空
 * @param objects
 * @return
 */
public static boolean isNUll(Object... objects) {
    for (Object object : objects) {
        if (object == null || "".equals(object) ) {
            return true;
        }
    }
    return false;
}

/**
 * 从request中取值
 * @param request
 * @return
 */
public static Map<String, Object> getParam(HttpServletRequest request){

    Map<String, String[]> parameterMap = request.getParameterMap();

    Map<String, Object> map = new HashMap<String, Object>(parameterMap.size());

    parameterMap.forEach((k,v) -> {
        if (!isNUll(v[0])) {
            map.put(k, v[0]);
        }
    });
    return map;
}
/**
 * 将字符串转为Integer
 * @param string
 * @return
 */
public static Integer str2int(String string) {
    if (isNUll(string)) {
        return null;
    }
    Integer val = 0;
    try {
        val = Integer.valueOf(string);
    } catch (NumberFormatException e) {
        // TODO: handle exception
    }
    return val;
}
/**
 * 将数据转为字符串
 * @param object
 * @return
 */
public static String array2str(Object[] object) {
    if (isNUll(object) || object.length < 1) {
        return null;
    }
    StringBuffer stringBuffer = new StringBuffer();
    for (Object obj : object) {
        stringBuffer.append(obj.toString().trim()).append(Constant.GOODS_SEPARAMETOR);
    }
    return stringBuffer.toString().substring(0,stringBuffer.length()-1);
}

/**
 * MD5加密
 * 
 * @param str
 * @return
 */
public static String encrypt(String str) {
    return encrypt(str, "md5");
}

/**
 * 信息摘要加密
 * 
 * @param str
 * @return
 */
public static String encrypt(String str, String type) {
    if (isNUll(str)) {
        return null;
    }
    try {
        MessageDigest md = MessageDigest.getInstance(type);
        byte[] bys = md.digest(str.getBytes());
        return new BASE64Encoder().encode(bys);
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return null;
}

/**
 * 获取请求的IP地址
 * 在apache+WebLogic整合系统中直接用request.getRemoteAddr()是无法取到真正的客户IP的。<br>
 * apache会增加下列头信息：<br>
 * X-Forwarded-For=21.1178.21.1 <br>
 * WL-Proxy-Client-IP=21.1178.21.1
 * 
 * @param request
 * @return
 */
public static String getIpAddr(HttpServletRequest request) {
    // 只有在通过了HTTP 代理或者负载均衡服务器时才会添加该项
    String ip = request.getHeader("X-Forwarded-For");
    // 如果客户端经过多级反向代理，则X-Forwarded-For的值并不止一个，而是一串IP值，
    // 取X-Forwarded-For中第一个非unknown的有效IP字符串即为用户真实IP
    String ipResult = getIp(ip);
    if (ipResult != null) {
        return ipResult;
    }

    // 代理服务器ip
    ip = request.getHeader("Proxy-Client-IP");
    ipResult = getIp(ip);
    if (!isNUll(ipResult) && !"unknown".equals(ipResult)) {
        return ipResult;
    }

    // weblogic集群下,获取客户端ip
    ip = request.getHeader("WL-Proxy-Client-IP");
    ipResult = getIp(ip);
    if (!isNUll(ipResult) && !"unknown".equals(ipResult)) {
        return ipResult;
    }

    ip = request.getRemoteAddr();
    ipResult = getIp(ip);
    if (!isNUll(ipResult) && !"unknown".equals(ipResult)) {
        return ipResult;
    }
    return "";
}

/**
 * 获取ip
 * 
 * @param ips
 * @return
 */
private static String getIp(String ips) {
    if (isNUll(ips)) {
        return null;
    }
    String[] tokens = ips.split(",");
    for (String s : tokens) {
        if (isIp(s.trim())) {
            return s.trim();
        }
    }
    return null;
}

/**
 * 给定的字符串是不是ip地址
 * 
 * @param value
 * @return
 */
public static boolean isIp(String value) {
    final String regValidatorIp = "^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}$";
    if (isNUll(value))
        return false;
    return value.matches(regValidatorIp);
}