spring-Security(二)：校验流程
spring-Security登录流程图如下，请仔细看
AbstractAuthenticationProcessingFilter 抽象类
/**
* 调用 #requiresAuthentication(HttpServletRequest, HttpServletResponse) 决定是否需要进行验证操作。
* 如果需要验证，则会调用 #attemptAuthentication(HttpServletRequest, HttpServletResponse) 方法。
* 有三种结果：
* 1、返回一个 Authentication 对象。
* 配置的 SessionAuthenticationStrategy` 将被调用，
* 然后 然后调用 #successfulAuthentication(HttpServletRequest，HttpServletResponse，FilterChain，Authentication) 方法。
* 2、验证时发生 AuthenticationException。
* #unsuccessfulAuthentication(HttpServletRequest, HttpServletResponse, AuthenticationException) 方法将被调用。
* 3、返回Null，表示身份验证不完整。假设子类做了一些必要的工作（如重定向）来继续处理验证，方法将立即返回。
* 假设后一个请求将被这种方法接收，其中返回的Authentication对象不为空。
*/
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
if (!requiresAuthentication(request, response)) {
chain.doFilter(request, response);
return;
}
if (logger.isDebugEnabled()) {
logger.debug("Request is to process authentication");
}
Authentication authResult;
try {
authResult = attemptAuthentication(request, response);
if (authResult == null) {
// return immediately as subclass has indicated that it hasn't completed
// authentication
return;
}
sessionStrategy.onAuthentication(authResult, request, response);
}
catch (InternalAuthenticationServiceException failed) {
logger.error(
"An internal error occurred while trying to authenticate the user.",
failed);
unsuccessfulAuthentication(request, response, failed);
return;
}
catch (AuthenticationException failed) {
// Authentication failed
unsuccessfulAuthentication(request, response, failed);
return;
}
// Authentication success
if (continueChainBeforeSuccessfulAuthentication) {
chain.doFilter(request, response);
}
successfulAuthentication(request, response, chain, authResult);
}
UsernamePasswordAuthenticationFilter（AbstractAuthenticationProcessingFilter的子类）
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();
UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(
username, password);
// Allow subclasses to set the "details" property
setDetails(request, authRequest);
return this.getAuthenticationManager().authenticate(authRequest);
}
#attemptAuthentication () 方法将 request 中的 username 和 password 生成 UsernamePasswordAuthenticationToken 对象，用于 AuthenticationManager 的验证（即 this.getAuthenticationManager().authenticate(authRequest) ）。
默认情况下注入 Spring 容器的 AuthenticationManager 是 ProviderManager。
ProviderManager（AuthenticationManager的实现类）
/**
* 尝试验证 Authentication 对象
* AuthenticationProvider 列表将被连续尝试，直到 AuthenticationProvider 表示它能够认证传递的过来的Authentication 对象。然后将使用该 AuthenticationProvider 尝试身份验证。
* 如果有多个 AuthenticationProvider 支持验证传递过来的Authentication 对象，那么由第一个来确定结果，覆盖早期支持AuthenticationProviders 所引发的任何可能的AuthenticationException。 成功验证后，将不会尝试后续的AuthenticationProvider。
* 如果最后所有的 AuthenticationProviders 都没有成功验证 Authentication 对象，将抛出 AuthenticationException。
*/
public Authentication authenticate(Authentication authentication)
throws AuthenticationException {
Class toTest = authentication.getClass();
AuthenticationException lastException = null;
Authentication result = null;
boolean debug = logger.isDebugEnabled();
for (AuthenticationProvider provider : getProviders()) {
if (!provider.supports(toTest)) {
continue;
}
if (debug) {
logger.debug("Authentication attempt using "
+ provider.getClass().getName());
}
try {
result = provider.authenticate(authentication);
if (result != null) {
copyDetails(authentication, result);
break;
}
}
catch (AccountStatusException e) {
prepareException(e, authentication);
// SEC-546: Avoid polling additional providers if auth failure is due to
// invalid account status
throw e;
}
catch (InternalAuthenticationServiceException e) {
prepareException(e, authentication);
throw e;
}
catch (AuthenticationException e) {
lastException = e;
}
}
if (result == null && parent != null) {
// Allow the parent to try.
try {
result = parent.authenticate(authentication);
}
catch (ProviderNotFoundException e) {
// ignore as we will throw below if no other exception occurred prior to
// calling parent and the parent
// may throw ProviderNotFound even though a provider in the child already
// handled the request
}
catch (AuthenticationException e) {
lastException = e;
}
}
if (result != null) {
if (eraseCredentialsAfterAuthentication
&& (result instanceof CredentialsContainer)) {
// Authentication is complete. Remove credentials and other secret data
// from authentication
((CredentialsContainer) result).eraseCredentials();
}
eventPublisher.publishAuthenticationSuccess(result);
return result;
}
// Parent was null, or didn't authenticate (or throw an exception).
if (lastException == null) {
lastException = new ProviderNotFoundException(messages.getMessage(
"ProviderManager.providerNotFound",
new Object[] { toTest.getName() },
"No AuthenticationProvider found for {0}"));
}
prepareException(lastException, authentication);
throw lastException;
}从代码中不难看出，由 provider 来验证 authentication， 核心点方法是：
Authentication result = provider.authenticate(authentication);AbstractUserDetailsAuthenticationProvider 是AuthenticationProvider的实现，看看它的 #authenticate(authentication) 方法：
// 验证 authentication
public Authentication authenticate(Authentication authentication)
throws AuthenticationException {
Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication,
messages.getMessage(
"AbstractUserDetailsAuthenticationProvider.onlySupports",
"Only UsernamePasswordAuthenticationToken is supported"));
// Determine username
String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED"
: authentication.getName();
boolean cacheWasUsed = true;
UserDetails user = this.userCache.getUserFromCache(username);
if (user == null) {
cacheWasUsed = false;
try {
user = retrieveUser(username,
(UsernamePasswordAuthenticationToken) authentication);
}
catch (UsernameNotFoundException notFound) {
logger.debug("User '" + username + "' not found");
if (hideUserNotFoundExceptions) {
throw new BadCredentialsException(messages.getMessage(
"AbstractUserDetailsAuthenticationProvider.badCredentials",
"Bad credentials"));
}
else {
throw notFound;
}
}
Assert.notNull(user,
"retrieveUser returned null - a violation of the interface contract");
}
try {
preAuthenticationChecks.check(user);
additionalAuthenticationChecks(user,
(UsernamePasswordAuthenticationToken) authentication);
}
catch (AuthenticationException exception) {
if (cacheWasUsed) {
// There was a problem, so try again after checking
// we're 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();
}
return createSuccessAuthentication(principalToReturn, authentication, user);
}
AbstractUserDetailsAuthenticationProvider 内置了缓存机制，从缓存中获取不到的 UserDetails 信息的话，就调用如下方法获取用户信息，然后和 用户传来的信息进行对比来判断是否验证成功。
// 获取用户信息
UserDetails user = retrieveUser(username,
(UsernamePasswordAuthenticationToken) authentication);#retrieveUser() 方法在 DaoAuthenticationProvider 中实现，DaoAuthenticationProvider
是 AbstractUserDetailsAuthenticationProvider的子类。具体实现如下：
protected final UserDetails retrieveUser(String username,
UsernamePasswordAuthenticationToken authentication)
throws AuthenticationException {
UserDetails loadedUser;
try {
loadedUser = this.getUserDetailsService().loadUserByUsername(username);
}
catch (UsernameNotFoundException notFound) {
if (authentication.getCredentials() != null) {
String presentedPassword = authentication.getCredentials().toString();
passwordEncoder.isPasswordValid(userNotFoundEncodedPassword,
presentedPassword, null);
}
throw notFound;
}
catch (Exception repositoryProblem) {
throw new InternalAuthenticationServiceException(
repositoryProblem.getMessage(), repositoryProblem);
}
if (loadedUser == null) {
throw new InternalAuthenticationServiceException(
"UserDetailsService returned null, which is an interface contract violation");
}
return loadedUser;
}
到了此处，就很清晰啦。
该文章基本来自这个大神,大家可以去看看
链接：https://www.jianshu.com/p/d425f8031f83