【#yyds干货盘点#Spring专题「实战系列」Spring Security原理以及实战认证分析开发指南】世事洞明皆学问，人情练达即文章。这篇文章主要讲述#yyds干货盘点#Spring专题「实战系列」Spring Security原理以及实战认证分析开发指南相关的知识，希望能为你提供帮助。
前提介绍
本篇文章给大家带来的内容是关于Spring Security原理的介绍，对实际业务开发会有一定的参考价值，希望对你有所帮助。所谓知彼知己方能百战百胜，用Spring Security来满足我们的需求最好了解其原理，这样才能随意拓展，本篇文章主要记录 Spring Security 的基本运行流程。
过滤器的原理机制
Spring Security基本都是通过过滤器来完成配置的身份认证、权限认证以及登出。
Spring Security在Servlet的过滤链（filter chain）中注册了一个过滤器 FilterChainProxy，它会把请求代理到Spring Security自己维护的多个过滤链，每个过滤链会匹配一些URL，如果匹配则执行对应的过滤器，过滤链是有顺序的，一个请求只会执行第一条匹配的过滤链。
Spring Security 的配置本质上就是新增、删除、修改过滤器。
文章图片
默认情况下系统帮我们注入的这15个过滤器，分别对应配置不同的需求。
认证控制过滤器UsernamePasswordAuthenticationFilter
接下来我们重点是分析下 UsernamePasswordAuthenticationFilter 这个过滤器，他是用来使用用户名和密码登录认证的过滤器，但是很多情况下我们的登录不止是简单的用户名和密码，又可能是用到第三方授权登录，这个时候我们就需要使用自定义过滤器，当然这里不做详细说明，只是说下自定义过滤器怎么注入。
@Override
protected void configure(HttpSecurity http) throws Exception {
http.addFilterAfter(...);
...
}身份认证流程在开始身份认证流程之前我们需要了解下几个基本概念：
SecurityContextHolderSecurityContextHolder存储SecurityContext对象。SecurityContextHolder是一个存储代理，有三种存储模式分别是：
- MODE_THREADLOCAL：SecurityContext 存储在线程中。
- MODE_INHERITABLETHREADLOCAL：SecurityContext 存储在线程中，但子线程可以获取到父线程中的 SecurityContext。
- MODE_GLOBAL：SecurityContext 在所有线程中都相同。
SecurityContext context = SecurityContextHolder.getContext();
Authentication authentication = context.getAuthentication();
AuthenticationAuthentication即验证，表明当前用户是谁。什么是验证，比如，一组用户名和密码就是验证，当然错误的用户名和密码也是验证，只不过 Spring Security会校验失败。
Authentication接口
public interface Authentication extends Principal, Serializable {
Collection getAuthorities();
Object getCredentials();
Object getDetails();
Object getPrincipal();
boolean isAuthenticated();
void setAuthenticated(boolean isAuthenticated);
}- getAuthorities()：获取用户权限，一般情况下获取到的是用户的角色信息。
- getCredentials()：获取证明用户认证的信息，通常情况下获取到的是密码等信息，不过登录成功就会被移除。
- getDetails()：获取用户的额外信息，比如 IP 地址、经纬度等
- getPrincipal()：获取用户身份信息，在未认证的情况下获取到的是用户名，在已认证的情况下获取到的是 UserDetails (暂时理解为，当前应用用户对象的扩展)
- isAuthenticated()：获取当前 Authentication 是否已认证
- setAuthenticated：设置当前 Authentication 是否已认证
- AuthenticationManager：主要就是为了完成身份认证流程。
- ProviderManager：AuthenticationManager 接口的具体实现类
- ProviderManager 里面有个记录AuthenticationProvider对象的集合属性 providers
- AuthenticationProvider接口类里有两个方法
public interface AuthenticationProvider {
//实现具体的身份认证逻辑，认证失败抛出对应的异常
Authentication authenticate(Authentication authentication)
throws AuthenticationException;
//该认证类是否支持该 Authentication 的认证
boolean supports(Class authentication);
}接下来就是遍历 ProviderManager 里面的 providers 集合，找到和合适的 AuthenticationProvider 完成身份认证。
UserDetailsService UserDetails在 UserDetailsService 接口中只有一个简单的方法
public interface UserDetailsService {
//根据用户名查到对应的 UserDetails 对象
UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;
}执行认证流程慢慢分析在运行到 UsernamePasswordAuthenticationFilter过滤器的时候。
首先是进入其父类AbstractAuthenticationProcessingFilter的doFilter()方法中
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)throws IOException, ServletException {
...
//首先配对是不是配置的身份认证的URI,是则执行下面的认证,不是则跳过
if (!requiresAuthentication(request, response)) {
chain.doFilter(request, response);
return;
}
...
Authentication authResult;
try {
//关键方法, 实现认证逻辑并返回 Authentication, 由其子类 UsernamePasswordAuthenticationFilter 实现
authResult = attemptAuthentication(request, response);
if (authResult == null) {
// return immediately as subclass has indicated that it hasnt completed
// authentication
return;
}
sessionStrategy.onAuthentication(authResult, request, response);
}
catch (InternalAuthenticationServiceException failed) {
//认证失败调用
unsuccessfulAuthentication(request, response, failed);
return;
}catch (AuthenticationException failed) {
//认证失败调用
unsuccessfulAuthentication(request, response, failed);
return;
}
// Authentication success
if (continueChainBeforeSuccessfulAuthentication) {
chain.doFilter(request, response);
}
//认证成功调
successfulAuthentication(request, response, chain, authResult);
}认证失败处理逻辑
protected void unsuccessfulAuthentication(HttpServletRequest request,HttpServletResponse response, AuthenticationException failed)throws IOException, ServletException {
SecurityContextHolder.clearContext();
...
rememberMeServices.loginFail(request, response);
//该 handler 处理失败界面跳转和响应逻辑
failureHandler.onAuthenticationFailure(request, response, failed);
}默认配置的失败处理 handler是 SimpleUrlAuthenticationFailureHandler，可自定义。
public class SimpleUrlAuthenticationFailureHandler implements
AuthenticationFailureHandler {
...
public void onAuthenticationFailure(HttpServletRequest request,
HttpServletResponse response, AuthenticationException exception)throws IOException, ServletException {
//没有配置失败跳转的URL则直接响应错误
if (defaultFailureUrl == null) {
logger.debug("No failure URL set, sending 401 Unauthorized error");
response.sendError(HttpStatus.UNAUTHORIZED.value(),
HttpStatus.UNAUTHORIZED.getReasonPhrase());
}else {
//否则
//缓存异常
saveException(request, exception);
//根据配置的异常页面是重定向还是转发进行不同方式跳转
if (forwardToDestination) {
logger.debug("Forwarding to " + defaultFailureUrl);
request.getRequestDispatcher(defaultFailureUrl)
.forward(request, response);
}else {
logger.debug("Redirecting to " + defaultFailureUrl);
redirectStrategy.sendRedirect(request, response, defaultFailureUrl);
}
}
}
//缓存异常,转发则保存在request里面,重定向则保存在session里面
protected final void saveException(HttpServletRequest request,
AuthenticationException exception) {
if (forwardToDestination) {
request.setAttribute(WebAttributes.AUTHENTICATION_EXCEPTION, exception);
}else {
HttpSession session = request.getSession(false);
if (session != null || allowSessionCreation) {
request.getSession().setAttribute(WebAttributes.AUTHENTICATION_EXCEPTION,exception);
}
}
}
}这里做下小拓展：用系统的错误处理handler，指定认证失败跳转的URL，在MVC里面对应的URL方法里面可以通过key从request或session里面拿到错误信息，反馈给前端。
认证成功处理逻辑
protected void successfulAuthentication(HttpServletRequest request,
HttpServletResponse response, FilterChain chain, Authentication authResult)
throws IOException, ServletException {
...
//这里要注意很重要，将认证完成返回的Authentication保存到线程对应的 `SecurityContext` 中
SecurityContextHolder.getContext().setAuthentication(authResult);
rememberMeServices.loginSuccess(request, response, authResult);
// Fire event
if (this.eventPublisher != null) {
eventPublisher.publishEvent(new InteractiveAuthenticationSuccessEvent(authResult, this.getClass()));
}
//该 handler 就是为了完成页面跳转
successHandler.onAuthenticationSuccess(request, response, authResult);
}这里默认配置的成功处理 handler 是 SavedRequestAwareAuthenticationSuccessHandler，里面的代码就不做具体展开了，反正是跳转到指定的认证成功之后的界面，可自定义。
身份认证详情
public class UsernamePasswordAuthenticationFilter extends
AbstractAuthenticationProcessingFilter {
...
public static final String SPRING_SECURITY_FORM_USERNAME_KEY = "username";
public static final String SPRING_SECURITY_FORM_PASSWORD_KEY = "password";
private String usernameParameter = SPRING_SECURITY_FORM_USERNAME_KEY;
private String passwordParameter = SPRING_SECURITY_FORM_PASSWORD_KEY;
private boolean postOnly = true;
...//开始身份认证逻辑
public Authentication attemptAuthentication(HttpServletRequest request,
HttpServletResponse response) throws AuthenticationException {
if (postOnly &
&
!request.getMethod().equals("POST")) {
throw new AuthenticationServiceException(
"Authentication method not supported: " + request.getMethod());
}
String username = obtainUsername(request);
String password = obtainPassword(request);
if (username == null) {
username = "";
}
if (password == null) {
password = "";
}
username = username.trim();
//先用前端提交过来的 username 和 password 封装一个简易的 AuthenticationToken
UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(
username, password);
// Allow subclasses to set the "details" property
setDetails(request, authRequest);
//具体的认证逻辑还是交给 AuthenticationManager 对象的 authenticate(..) 方法完成,接着往下看
return this.getAuthenticationManager().authenticate(authRequest);
}
}由源码断点跟踪得知，最终解析是由 AuthenticationManager 接口实现类 ProviderManager 来完成
public class ProviderManager implements AuthenticationManager, MessageSourceAware,InitializingBean {
...
private List providers = Collections.emptyList();
...
public Authentication authenticate(Authentication authentication)
throws AuthenticationException {
....
//遍历所有的 AuthenticationProvider, 找到合适的完成身份验证
for (AuthenticationProvider provider : getProviders()) {
if (!provider.supports(toTest)) {
continue;
}
...
try {
//进行具体的身份验证逻辑, 这里使用到的是 DaoAuthenticationProvider, 具体逻辑记着往下看
result = provider.authenticate(authentication);
if (result != null) {
copyDetails(authentication, result);
break;
}
}catch
...
}
...
throw lastException;
}
}DaoAuthenticationProviderDaoAuthenticationProvider继承自 AbstractUserDetailsAuthenticationProvider实现AuthenticationProvider接口
public abstract class AbstractUserDetailsAuthenticationProvider implements
AuthenticationProvider, InitializingBean, MessageSourceAware {
...
private UserDetailsChecker preAuthenticationChecks = new DefaultPreAuthenticationChecks();
private UserDetailsChecker postAuthenticationChecks = new DefaultPostAuthenticationChecks();
...
public Authentication authenticate(Authentication authentication)
throws AuthenticationException {
...
// 获得提交过来的用户名
String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED" : authentication.getName();
//根据用户名从缓存中查找 UserDetails
boolean cacheWasUsed = true;
UserDetails user = this.userCache.getUserFromCache(username);
if (user == null) {
cacheWasUsed = false;
try {
//缓存中没有则通过 retrieveUser(..) 方法查找 (看下面 DaoAuthenticationProvider 的实现)
user = retrieveUser(username,
(UsernamePasswordAuthenticationToken) authentication);
}catch
...
}
try {
//比对前的检查,例如账户以一些状态信息(是否锁定, 过期...)
preAuthenticationChecks.check(user);
//子类实现比对规则 (看下面 DaoAuthenticationProvider 的实现)
additionalAuthenticationChecks(user,
(UsernamePasswordAuthenticationToken) authentication);
}catch (AuthenticationException exception) {
if (cacheWasUsed) {
// There was a problem, so try again after checking
// were using latest data (i.e. not from the cache)
cacheWasUsed = false;
user = retrieveUser(username,
(UsernamePasswordAuthenticationToken) authentication);
preAuthenticationChecks.check(user);
additionalAuthenticationChecks(user,
(UsernamePasswordAuthenticationToken) authentication);
}else {
throw exception;
}
}
postAuthenticationChecks.check(user);
if (!cacheWasUsed) {
this.userCache.putUserInCache(user);
}
Object principalToReturn = user;
if (forcePrincipalAsString) {
principalToReturn = user.getUsername();
}
//根据最终user的一些信息重新生成具体详细的 Authentication 对象并返回
return createSuccessAuthentication(principalToReturn, authentication, user);
}
//具体生成还是看子类实现
protected Authentication createSuccessAuthentication(Object principal,Authentication authentication, UserDetails user) {
// Ensure we return the original credentials the user supplied,
// so subsequent attempts are successful even with encoded passwords.
// Also ensure we return the original getDetails(), so that future
// authentication events after cache expiry contain the details
UsernamePasswordAuthenticationToken result = new UsernamePasswordAuthenticationToken(
principal, authentication.getCredentials(),
authoritiesMapper.mapAuthorities(user.getAuthorities()));
result.setDetails(authentication.getDetails());
return result;
}
}接下来我们来看下 DaoAuthenticationProvider 里面的三个重要的方法，比对方式、获取需要比对的 UserDetails 对象以及生产最终返回 Authentication 的方法。
public class DaoAuthenticationProvider extends AbstractUserDetailsAuthenticationProvider {
...
//密码比对
@SuppressWarnings("deprecation")
protected void additionalAuthenticationChecks(UserDetails userDetails,UsernamePasswordAuthenticationToken authentication)
throws AuthenticationException {
if (authentication.getCredentials() == null) {
logger.debug("Authentication failed: no credentials provided");
throw new BadCredentialsException(messages.getMessage(
"AbstractUserDetailsAuthenticationProvider.badCredentials",
"Bad credentials"));
}
String presentedPassword = authentication.getCredentials().toString();
//通过 PasswordEncoder 进行密码比对, 注: 可自定义
if (!passwordEncoder.matches(presentedPassword, userDetails.getPassword())) {
logger.debug("Authentication failed: password does not match stored value");
throw new BadCredentialsException(messages.getMessage(
"AbstractUserDetailsAuthenticationProvider.badCredentials",
"Bad credentials"));
}
}
//通过 UserDetailsService 获取 UserDetails
protected final UserDetails retrieveUser(String username,
UsernamePasswordAuthenticationToken authentication)
throws AuthenticationException {
prepareTimingAttackProtection();
try {
//通过 UserDetailsService 获取 UserDetails
UserDetails loadedUser = this.getUserDetailsService().loadUserByUsername(username);
if (loadedUser == null) {
throw new InternalAuthenticationServiceException(
"UserDetailsService returned null, which is an interface contract violation");
}
return loadedUser;
}
catch (UsernameNotFoundException ex) {
mitigateAgainstTimingAttack(authentication);
throw ex;
}
catch (InternalAuthenticationServiceException ex) {
throw ex;
}
catch (Exception ex) {
throw new InternalAuthenticationServiceException(ex.getMessage(), ex);
}
}
//生成身份认证通过后最终返回的 Authentication, 记录认证的身份信息
@Override
protected Authentication createSuccessAuthentication(Object principal,Authentication authentication, UserDetails user) {
boolean upgradeEncoding = this.userDetailsPasswordService != null &
&
this.passwordEncoder.upgradeEncoding(user.getPassword());
if (upgradeEncoding) {
String presentedPassword = authentication.getCredentials().toString();
String newPassword = this.passwordEncoder.encode(presentedPassword);
user = this.userDetailsPasswordService.updatePassword(user, newPassword);
}
return super.createSuccessAuthentication(principal, authentication, user);
}
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