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防止刷新/后退引起的重复提交

2013-10-25 12:59 78 查看
Token主类:

import java.util.ArrayList;

import javax.servlet.http.HttpSession;

public class Token {

private static final String TOKEN_LIST_NAME = "tokenList";

public static final String TOKEN_STRING_NAME = "token";

private static ArrayList getTokenList(HttpSession session) {

Object obj = session.getAttribute(TOKEN_LIST_NAME);

if (obj != null) {

return (ArrayList) obj;

} else {

ArrayList tokenList = new ArrayList();

session.setAttribute(TOKEN_LIST_NAME, tokenList);

return tokenList;

}

}

private static void saveTokenString(String tokenStr, HttpSession session) {

ArrayList tokenList = getTokenList(session);

tokenList.add(tokenStr);

session.setAttribute(TOKEN_LIST_NAME, tokenList);

}

private static String generateTokenString(){

return new Long(System.currentTimeMillis()).toString();

}

/** *//**

* Generate a token string, and save the string in session, then return the token string.

*

* @param HttpSession

* session

* @return a token string used for enforcing a single request for a particular transaction.

*/

public static String getTokenString(HttpSession session) {

String tokenStr = generateTokenString();

saveTokenString(tokenStr, session);

return tokenStr;

}

/** *//**

* check whether token string is valid. if session contains the token string, return true.

* otherwise, return false.

*

* @param String

* tokenStr

* @param HttpSession

* session

* @return true: session contains tokenStr; false: session is null or tokenStr is id not in session

*/

public static boolean isTokenStringValid(String tokenStr, HttpSession session) {

boolean valid = false;

if(session != null){

ArrayList tokenList = getTokenList(session);

if (tokenList.contains(tokenStr)) {

valid = true;

tokenList.remove(tokenStr);

}

}

return valid;

}

}

在页面引入这个类

表单包含隐藏的Token字符串:

<form>

<input type="hidden" name="<%=Token.TOKEN_STRING_NAME %>" value="<%=Token.getTokenString(session) %>">

</form>

在Server端action中进行检验

if(Token.isTokenStringValid(request.getParameter(Token.TOKEN_STRING_NAME), request.getSession())){

//进行正常业务流程

}

else{

//进行防重复提交处理流程

}
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