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)。
实现如下:
TokenInterceptor拦截器
public class TokenInterceptor implements HandlerInterceptor{
private static Map<String,String> viewUrls=new HashMap<String,String>();
private static Map<String,String> actionUrls=new HashMap<String,String>();
private static Map<String,String> redisCacheClient = new HashMap<String,String>();//模拟redis缓存
static
viewUrls.put("/springmvc/regPage.action", "get"); //注册页面 /springmvc为我的项目名:http://localhost:8080/springmvc/regAction.action
//如果你是直接通过localhost/regAction.action访问的话去掉/springmvc
actionUrls.put("/springmvc/regAction.action", "post");//注册提交
}
{
TokenHelper.setRedisCacheClient(redisCacheClient);
}
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object handler) throws Exception {
String requestURI=request.getRequestURI();
String method = request.getMethod();
//如果请求的是页面
if(viewUrls.keySet().contains(requestURI) &&(viewUrls.get(requestURI)==null || viewUrls.get(requestURI).equalsIgnoreCase(method))){
TokenHelper.setToken(request);
return true;
}else if(actionUrls.keySet().contains(requestURI) &&(actionUrls.get(requestURI)==null || actionUrls.get(requestURI).equalsIgnoreCase(method))){
//如果是注册提交
return handlerToke(request,response,handler);
}
return true;
}
private boolean handlerToke(HttpServletRequest request, HttpServletResponse response, Object handler) {
if(TokenHelper.validHandler(request)){
return handlerValidToken(request,response,handler);
}else{
return handlerInvalid(request,response,handler);
}
}
private boolean handlerInvalid(HttpServletRequest request,
HttpServletResponse response, Object handler) {
try {
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("请不要重复提交!");
} catch (IOException e) {
e.printStackTrace();
}finally{
try {
response.getWriter().close();
} catch (IOException e) {
e.printStackTrace();
}
}
return false;
}
private boolean handlerValidToken(HttpServletRequest request,
HttpServletResponse response, Object handler) {
return true;
}
@Override
public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1,
Object arg2, ModelAndView arg3) throws Exception {
}
@Override
public void afterCompletion(HttpServletRequest arg0,
HttpServletResponse arg1, Object arg2, Exception arg3)
throws Exception {
}
}
<pre name="code" class="java">TokenHelper.java
public class TokenHelper {
private static Map<String,String> redisCacheClient = new HashMap<String,String>();//模拟redis缓存
public static final String TOKEN_NAMESPACE = "com.tokens";
public static final String TOKEN_NAME_FIELD = "tokenName";
public static final String TOKEN__FIELD = "token";
private static final Random RANDOM = new Random();
public static void setToken(HttpServletRequest request) {
String token = generateGUID();
String tokenName = generateGUID();
String redisTokenName = TOKEN_NAMESPACE+"."+tokenName;
redisCacheClient.put(redisTokenName, token);
request.setAttribute(TOKEN_NAME_FIELD, tokenName);//tokenName和token都要放到表单隐藏域中,tokenName的作用是用来区分不同的表单(不局限与注册页面)
request.setAttribute(TOKEN__FIELD, token);
}
public static boolean validHandler(HttpServletRequest request) {
String tokenName = getTokenName(request);
String token = getToken(request,tokenName);
if(tokenName!=null&&tokenName!=""){
String redisToken = redisCacheClient.get(TOKEN_NAMESPACE+"."+tokenName);
if(redisToken!=null&&redisToken!="" && redisToken!="null"){
if(redisToken.endsWith(token)){
redisCacheClient.put(TOKEN_NAMESPACE+"."+tokenName, null);//从缓存中移除token
return true;
}
}
}
return false;
}
private static String getToken(HttpServletRequest request, String tokenName) {
if(tokenName==null){
return null;
}
// Map<String, String[]> parameterMap = request.getParameterMap();
// String[] tokens = (String[]) (String[]) parameterMap.get(tokenName);
String token = request.getParameter(tokenName);
if(token==null||token==""){
return null;
}
return token;
}
private static String getTokenName(HttpServletRequest request) {
Map<String, String[]> parameterMap = request.getParameterMap();
String[] names = parameterMap.get(TokenHelper.TOKEN_NAME_FIELD);
if(names==null || names.length<1){
return null;
}
return names[0];
}
public static String generateGUID()
{
return new BigInteger(165, RANDOM).toString(36).toUpperCase();
}
public static Map<String, String> getRedisCacheClient() {
return redisCacheClient;
}
public static void setRedisCacheClient(Map<String, String> redisCacheClient) {
TokenHelper.redisCacheClient = redisCacheClient;
}
}
控制器:TokenController.java
@Controller
public class TokenController {
@RequestMapping("/regPage.action")
public String regPage(){
return "reg";
}
@RequestMapping("/regAction.action")
public ModelAndView regAction(String name,Model model){
model.addAttribute("name", name);
ModelAndView m = new ModelAndView();
m.setViewName("/success");
return m;
}
}
注册页面:reg.jsp
<form action="/springmvc/regAction.action" method="post">
<input type="hidden" name="${tokenName}" value="${token}"/>
<input type="hidden" name="tokenName" value="${tokenName}"/>
<input type="text" name="name">
<input type="submit" value="提交">
</form>
success.jsp
success:${name}
springmvc.xml配置拦截器:
<mvc:interceptors>
<!-- 使用bean定义一个Interceptor,直接定义在mvc:interceptors根下面的Interceptor将拦截所有的请求 -->
<bean class="com.yjp.interceptor.TokenInterceptor"/>
</mvc:interceptors>
测试结果:访问:http://localhost:8080/springmvc/regPage.action 提交表单后 浏览器再后退 再次提交表单 提示请不要重复提交表单