SpringMVC防止重复提交

问题描述：

现在的网站在注册步骤中，由于后台要处理大量信息，造成响应变慢（测试机器性能差也是造成变慢的一个因素），在前端页面提交信息之前，等待后端响应，此时如果用户
再点一次提交按钮，后台会保存多份用户信息。为解决此问题，借鉴了struts2的token思路，在springmvc下实现token。

实现思路：

在springmvc配置文件中加入拦截器的配置，拦截两类请求，一类是到页面的，一类是提交表单的。当转到页面的请求到来时，生成token的名字和token值，一份放到redis缓存中，一份放传给页面表单的隐藏域。（注：这里之所以使用redis缓存，是因为tomcat服务器是集群部署的，要保证token的存储介质是全局线程安全的，而redis是单线程的）

当表单请求提交时，拦截器得到参数中的tokenName和token，然后到缓存中去取token值，如果能匹配上，请求就通过，不能匹配上就不通过。这里的tokenName生成时也是随机的，每次请求都不一样。而从缓存中取token值时，会立即将其删除（删与读是原子的，无线程安全问题）。

实现方式：

TokenInterceptor.java

package com.xxx.www.common.interceptor;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import com.xxx.cache.redis.IRedisCacheClient;
import com.xxx.common.utility.JsonUtil;
import com.xxx.www.common.utils.TokenHelper;

/**
 * 
 * @see TokenHelper
 */
public class TokenInterceptor extends HandlerInterceptorAdapter
{  
    private static Logger log = Logger.getLogger(TokenInterceptor.class);
    private static Map<String , String> viewUrls = new HashMap<String , String>();
    private static Map<String , String> actionUrls = new HashMap<String , String>();
    private Object clock = new Object();    
    @Autowired
    private IRedisCacheClient redisCacheClient;
    static
    {
        viewUrls.put("/user/regc/brandregnamecard/", "GET");
        viewUrls.put("/user/regc/regnamecard/", "GET");     
        actionUrls.put("/user/regc/brandregnamecard/", "POST");
        actionUrls.put("/user/regc/regnamecard/", "POST");
    }
    {
        TokenHelper.setRedisCacheClient(redisCacheClient);
    }    
    /**
     * 拦截方法，添加or验证token
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
    {
        String url = request.getRequestURI();
        String method = request.getMethod();
        if(viewUrls.keySet().contains(url) && ((viewUrls.get(url)) == null || viewUrls.get(url).equals(method)))
        {
            TokenHelper.setToken(request);
            return true;
        }
        else if(actionUrls.keySet().contains(url) && ((actionUrls.get(url)) == null || actionUrls.get(url).equals(method)))
        {
            log.debug("Intercepting invocation to check for valid transaction token.");
            return handleToken(request, response, handler);
        }
        return true;
    }    
    protected boolean handleToken(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
    {
        synchronized(clock)
        {
            if(!TokenHelper.validToken(request))
            {
                System.out.println("未通过验证...");
                return handleInvalidToken(request, response, handler);
            }
        }
        System.out.println("通过验证...");
        return handleValidToken(request, response, handler);
    }
    
    /**
     * 当出现一个非法令牌时调用
     */
    protected boolean handleInvalidToken(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
    {
        Map<String , Object> data = new HashMap<String , Object>();
        data.put("flag", 0);
        data.put("msg", "请不要频繁操作！");
        writeMessageUtf8(response, data);
        return false;
    }    
    /**
     * 当发现一个合法令牌时调用.
     */
    protected boolean handleValidToken(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
    {
        return true;
    }
    
    private void writeMessageUtf8(HttpServletResponse response, Map<String , Object> json) throws IOException
    {
        try
        {
            response.setCharacterEncoding("UTF-8");
            response.getWriter().print(JsonUtil.toJson(json));
        }
        finally
        {
            response.getWriter().close();
        }
    }
    
}

TokenHelper.java

package com.xxx.www.common.utils;
import java.math.BigInteger;
import java.util.Map;
import java.util.Random;
import javax.servlet.http.HttpServletRequest;
import org.apache.log4j.Logger;
import com.xxx.cache.redis.IRedisCacheClient;

/**
 * TokenHelper
 * 
 */
public class TokenHelper
{   
    /**
     * 保存token值的默认命名空间
     */
    public static final String TOKEN_NAMESPACE = "xxx.tokens";    
    /**
     * 持有token名称的字段名
     */
    public static final String TOKEN_NAME_FIELD = "xxx.token.name";
    private static final Logger LOG = Logger.getLogger(TokenHelper.class);
    private static final Random RANDOM = new Random();  
    private static IRedisCacheClient redisCacheClient;// 缓存调用,代替session,支持分布式
    public static void setRedisCacheClient(IRedisCacheClient redisCacheClient)
    {
        TokenHelper.redisCacheClient = redisCacheClient;
    }    
    /**
     * 使用随机字串作为token名字保存token
     * 
     * @param request
     * @return token
     */
    public static String setToken(HttpServletRequest request)
    {
        return setToken(request, generateGUID());
    }    
    /**
     * 使用给定的字串作为token名字保存token
     * 
     * @param request
     * @param tokenName
     * @return token
     */
    private static String setToken(HttpServletRequest request, String tokenName)
    {
        String token = generateGUID();
        setCacheToken(request, tokenName, token);
        return token;
    }    
    /**
     * 保存一个给定名字和值的token
     * 
     * @param request
     * @param tokenName
     * @param token
     */
    private static void setCacheToken(HttpServletRequest request, String tokenName, String token)
    {
        try
        {
            String tokenName0 = buildTokenCacheAttributeName(tokenName);
            redisCacheClient.listLpush(tokenName0, token);
            request.setAttribute(TOKEN_NAME_FIELD, tokenName);
            request.setAttribute(tokenName, token);
        }
        catch(IllegalStateException e)
        {
            String msg = "Error creating HttpSession due response is commited to client. You can use the CreateSessionInterceptor or create the HttpSession from your action before the result is rendered to the client: " + e.getMessage();
            LOG.error(msg, e);
            throw new IllegalArgumentException(msg);
        }
    }    
    /**
     * 构建一个基于token名字的带有命名空间为前缀的token名字
     * 
     * @param tokenName
     * @return the name space prefixed session token name
     */
    public static String buildTokenCacheAttributeName(String tokenName)
    {
        return TOKEN_NAMESPACE + "." + tokenName;
    }
    
    /**
     * 从请求域中获取给定token名字的token值
     * 
     * @param tokenName
     * @return the token String or null, if the token could not be found
     */
    public static String getToken(HttpServletRequest request, String tokenName)
    {
        if(tokenName == null)
        {
            return null;
        }
        Map params = request.getParameterMap();
        String[] tokens = (String[]) (String[]) params.get(tokenName);
        String token;
        if((tokens == null) || (tokens.length < 1))
        {
            LOG.warn("Could not find token mapped to token name " + tokenName);
            return null;
        }
        
        token = tokens[0];
        return token;
    }    
    /**
     * 从请求参数中获取token名字
     * 
     * @return the token name found in the params, or null if it could not be found
     */
    public static String getTokenName(HttpServletRequest request)
    {
        Map params = request.getParameterMap();      
        if(!params.containsKey(TOKEN_NAME_FIELD))
        {
            LOG.warn("Could not find token name in params.");
            return null;
        }        
        String[] tokenNames = (String[]) params.get(TOKEN_NAME_FIELD);
        String tokenName;        
        if((tokenNames == null) || (tokenNames.length < 1))
        {
            LOG.warn("Got a null or empty token name.");
            return null;
        }      
        tokenName = tokenNames[0];   
        return tokenName;
    }    
    /**
     * 验证当前请求参数中的token是否合法，如果合法的token出现就会删除它，它不会再次成功合法的token
     * 
     * @return 验证结果
     */
    public static boolean validToken(HttpServletRequest request)
    {
        String tokenName = getTokenName(request);        
        if(tokenName == null)
        {
            LOG.debug("no token name found -> Invalid token ");
            return false;
        }        
        String token = getToken(request, tokenName);        
        if(token == null)
        {
            if(LOG.isDebugEnabled())
            {
                LOG.debug("no token found for token name " + tokenName + " -> Invalid token ");
            }
            return false;
        }        
        String tokenCacheName = buildTokenCacheAttributeName(tokenName);
        String cacheToken = redisCacheClient.listLpop(tokenCacheName);        
        if(!token.equals(cacheToken))
        {
            LOG.warn("xxx.internal.invalid.token Form token " + token + " does not match the session token " + cacheToken + ".");
            return false;
        }        
        // remove the token so it won't be used again        
        return true;
    }   
    public static String generateGUID()
    {
        return new BigInteger(165, RANDOM).toString(36).toUpperCase();
    }
    
}

spring-mvc.xml

<!-- token拦截器-->
    <bean id="tokenInterceptor" class="com.xxx.www.common.interceptor.TokenInterceptor"></bean>    
    <bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">    
        <property name="interceptors">    
            <list>    
                <ref bean="tokenInterceptor"/>    
            </list>
        </property>    
    </bean>

input.jsp 在form中加如下内容：

 <input type="hidden" name="<%=request.getAttribute("xxx.token.name") %>" value="<%=token %>"/>
<input type="hidden" name="xxx.token.name" value="<%=request.getAttribute("xxx.token.name") %>"/>

当前这里也可以用类似于struts2的自定义标签来做。