版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/andy_zhang2007/article/details/84937412
概述
缺省情况下，如果安全配置开启了Remember Me机制，用户在登录界面上会看到Remember Me选择框，如果用户选择了该选择框，会导致生成一个名为remember-me,属性httpOnly为true的cookie，其值是一个RememberMe token。
RememberMe token是一个Base64编码的字符串，解码后格式为{用户名}:{Token过期时间戳}:{Token签名摘要},比如:admin:1545787408479:d0b0e7a53960e94b521bee3f02ba0bf5
而该过滤器在每次请求到达时会检测SecurityContext属性Authentication是否已经设置。如果没有设置，会进入该过滤器的职责逻辑。它尝试获取名为remember-me的cookie,获取到的话会认为这是一次Remember Me登录尝试，从中分析出用户名,Token过期时间戳，签名摘要，针对用户库验证这些信息，认证通过的话，就会往SecurityContext里面设置Authentication为一个针对请求中所指定用户的RememberMeAuthenticationToken。
认证成功的话，也会向应用上下文发布事件InteractiveAuthenticationSuccessEvent。
默认情况下不管认证成功还是失败，请求都会被继续执行。
不过也可以指定一个
AuthenticationSuccessHandler给当前过滤器，这样当Remember Me登录认证成功时，处理委托给该AuthenticationSuccessHandler,而不再继续原请求的处理。利用这种机制，可以为Remember Me登录认证成功指定特定的跳转地址。
Remember Me登录认证成功并不代表用户一定可以访问到目标页面，因为如果Remember Me登陆认证成功对应用户访问权限级别为isRememberMe，而目标页面有可能需要更高的访问权限级别fullyAuthenticated。
如果你想观察该过滤器的行为，可以这么做：
- 在配置中开启
Remember Me机制，则此过滤器会被使用;- 启动应用，打开浏览器,提供正确的用户名密码，选择
Remember Me选项,然后提交完成一次成功的登录;- 关闭整个浏览器;
- 重新打开刚刚关闭的浏览器;
- 直接访问某个受登录保护的页面，你会看到该过滤器的职责逻辑被执行。
源代码解析
package org.springframework.security.web.authentication.rememberme;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.event.InteractiveAuthenticationSuccessEvent;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.authentication.AuthenticationSuccessHandler;
import org.springframework.security.web.authentication.RememberMeServices;
import org.springframework.util.Assert;
import org.springframework.web.filter.GenericFilterBean;
public class RememberMeAuthenticationFilter extends GenericFilterBean implements
ApplicationEventPublisherAware {
// ~ Instance fields
// =======================================================================================
private ApplicationEventPublisher eventPublisher;
private AuthenticationSuccessHandler successHandler;
private AuthenticationManager authenticationManager;
private RememberMeServices rememberMeServices;
public RememberMeAuthenticationFilter(AuthenticationManager authenticationManager,
RememberMeServices rememberMeServices) {
Assert.notNull(authenticationManager, "authenticationManager cannot be null");
Assert.notNull(rememberMeServices, "rememberMeServices cannot be null");
this.authenticationManager = authenticationManager;
this.rememberMeServices = rememberMeServices;
}
// ~ Methods
// =====================================================================================
@Override
public void afterPropertiesSet() {
Assert.notNull(authenticationManager, "authenticationManager must be specified");
Assert.notNull(rememberMeServices, "rememberMeServices must be specified");
}
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
if (SecurityContextHolder.getContext().getAuthentication() == null) {
// 如果SecurityContext中authentication为空则尝试 remember me 自动认证,
// 缺省情况下这里rememberMeServices会是一个TokenBasedRememberMeServices,
// 其自动 remember me 认证过程如下:
// 1. 获取 cookie remember-me 的值 , 一个base64 编码串;
// 2. 从上面cookie之中解析出信息:用户名，token 过期时间，token 签名
// 3. 检查用户是否存在，token是否过期，token 签名是否一致,
// 上面三个步骤都通过的情况下再检查一下账号是否锁定，过期，禁用，密码过期等现象,
// 如果上面这些验证都通过，则认为认证成功，会构造一个
// RememberMeAuthenticationToken并返回
// 上面的认证失败会有rememberMeAuth==null
Authentication rememberMeAuth = rememberMeServices.autoLogin(request,
response);
if (rememberMeAuth != null) {
// Attempt authenticaton via AuthenticationManager
try {
// 如果上面的 Remember Me 认证成功，则需要使用 authenticationManager
// 认证该rememberMeAuth
rememberMeAuth = authenticationManager.authenticate(rememberMeAuth);
// Store to SecurityContextHolder
// 将认证成功的rememberMeAuth放到SecurityContextHolder中的SecurityContext
SecurityContextHolder.getContext().setAuthentication(rememberMeAuth);
// 成功时的其他操作:空方法，其实没有其他在这里做
onSuccessfulAuthentication(request, response, rememberMeAuth);
if (logger.isDebugEnabled()) {
logger.debug("SecurityContextHolder populated with remember-me token: '"
+ SecurityContextHolder.getContext().getAuthentication()
+ "'");
}
// Fire event
if (this.eventPublisher != null) {
// 发布事件 InteractiveAuthenticationSuccessEvent 到应用上下文
eventPublisher
.publishEvent(new InteractiveAuthenticationSuccessEvent(
SecurityContextHolder.getContext()
.getAuthentication(), this.getClass()));
}
if (successHandler != null) {
// 如果指定了 successHandler ,则调用它，
// 缺省情况下这个 successHandler 为 null
successHandler.onAuthenticationSuccess(request, response,
rememberMeAuth);
// 如果指定了 successHandler，在它调用之后，不再继续 filter chain 的执行
return;
}
}
catch (AuthenticationException authenticationException) {
// Remember Me 认证失败的情况
if (logger.isDebugEnabled()) {
logger.debug(
"SecurityContextHolder not populated with remember-me token, as "
+ "AuthenticationManager rejected Authentication returned by RememberMeServices: '"
+ rememberMeAuth
+ "'; invalidating remember-me token",
authenticationException);
}
// rememberMeServices 的认证失败处理
rememberMeServices.loginFail(request, response);
// 空方法，这里什么都不做
onUnsuccessfulAuthentication(request, response,
authenticationException);
}
}
// 继续 filter chain 执行
chain.doFilter(request, response);
}
else {
if (logger.isDebugEnabled()) {
logger.debug("SecurityContextHolder not populated with remember-me token, as it already contained: '"
+ SecurityContextHolder.getContext().getAuthentication() + "'");
}
// 继续 filter chain 执行
chain.doFilter(request, response);
}
}
/**
* Called if a remember-me token is presented and successfully authenticated by the
* RememberMeServices autoLogin method and the
* AuthenticationManager.
*/
protected void onSuccessfulAuthentication(HttpServletRequest request,
HttpServletResponse response, Authentication authResult) {
}
/**
* Called if the AuthenticationManager rejects the authentication object
* returned from the RememberMeServices autoLogin method. This method
* will not be called when no remember-me token is present in the request and
* autoLogin reurns null.
*/
protected void onUnsuccessfulAuthentication(HttpServletRequest request,
HttpServletResponse response, AuthenticationException failed) {
}
public RememberMeServices getRememberMeServices() {
return rememberMeServices;
}
public void setApplicationEventPublisher(ApplicationEventPublisher eventPublisher) {
this.eventPublisher = eventPublisher;
}
/**
* Allows control over the destination a remembered user is sent to when they are
* successfully authenticated. By default, the filter will just allow the current
* request to proceed, but if an AuthenticationSuccessHandler is set, it will
* be invoked and the doFilter() method will return immediately, thus allowing
* the application to redirect the user to a specific URL, regardless of whatthe
* original request was for.
* 缺省情况下，Remember Me 登录认证成功时filter chain会继续执行。但是也允许指定一个
* AuthenticationSuccessHandler , 这样就可以控制 Remember Me 登录认证成功时的目标
* 跳转地址(当然会忽略原始的请求目标)。
* @param successHandler the strategy to invoke immediately before returning from
* doFilter().
*/
public void setAuthenticationSuccessHandler(
AuthenticationSuccessHandler successHandler) {
Assert.notNull(successHandler, "successHandler cannot be null");
this.successHandler = successHandler;
}
}