Java TokenProcessor令牌校验工具类

publicclassTokenProcessor {

privatelongprivious;// 上次生成表单标识号得时间值

privatestaticTokenProcessor instance =newTokenProcessor();

publicstaticString FORM_TOKEN_KEY ="FORM_TOKEN_KEY";

privateTokenProcessor() {

}

publicstaticTokenProcessor getInstance() {

returninstance;

}

/**

* 验证请求中得标识号是否有效，如果请求中的表单标识与当前用户session中的相同，返回结果true=

*/

publicsynchronizedbooleanisTokenValid(HttpServletRequest request) {

// 为避免session对象不存在时候创建Session对象

HttpSession session = request.getSession(false);

if(session ==null) {

returnfalse;

}

String saved = (String) session.getAttribute(FORM_TOKEN_KEY);

if(saved ==null) {

returnfalse;

}

String token = (String) request.getParameter(FORM_TOKEN_KEY);

if(token ==null) {

returnfalse;

}

returnsaved.equals(token);

}

/**

* 验证请求中得标识号是否有效，如果请求中的表单标识与当前用户session中的相同，返回结果true=

*/

publicsynchronizedbooleanisTokenValid(HttpServletRequest request,String token) {

// 未避免session对象不存在时候创建Session对象

HttpSession session = request.getSession(false);

if(session ==null) {

returnfalse;

}

String saved = (String) session.getAttribute(FORM_TOKEN_KEY);

if(saved ==null) {

returnfalse;

}

if(token ==null) {

returnfalse;

}

returnsaved.equals(token);

}

/**

* 清除存储在当前用户session中的表单标识号

*/

publicsynchronizedvoidreset(HttpServletRequest request) {

HttpSession session = request.getSession(false);

if(session ==null) {

return;

}

session.removeAttribute(FORM_TOKEN_KEY);

}

/**

* 产生表单标识号并将之保存在当前用户得session中

*/

publicsynchronizedvoidsaveToken(HttpServletRequest request) {

HttpSession session = request.getSession();

try{

byteid[] = session.getId().getBytes();

longcurrent = System.currentTimeMillis();

if(current == privious) {

current++;

}

privious = current;

bytenow[] = String.valueOf(current).getBytes();

MessageDigest md = MessageDigest.getInstance("MD5");

md.update(id);

md.update(now);

String token = toHex(md.digest());

session.setAttribute(FORM_TOKEN_KEY, token);

}catch(NoSuchAlgorithmException e) {

}

}

/**

* 将一个字节数转换成十六进制得字符串

*/

publicString toHex(bytebuffer[]) {

StringBuffer sb =newStringBuffer(buffer.length *2);

for(inti =0; i

sb.append(Character.forDigit((buffer[i] &0x60) >>4,16));

sb.append(Character.forDigit(buffer[i] &0x0f,16));

}

returnsb.toString();

}

}