這篇文章帶給大家的內容是關於Spring Security原理的介紹（附程式碼），有一定的參考價值，有需要的朋友可以參考一下，希望對你有幫助。
知彼知己方能百戰百勝，用 Spring Security 來滿足我們的需求最好了解其原理，這樣才能隨意拓展，本篇文章主要記錄 Spring Security 的基本運作流程。
過濾器
Spring Security 基本上都是透過過濾器來完成配置的身份認證、權限認證以及登出。
Spring Security 在Servlet 的過濾鏈（filter chain）中註冊了一個過濾器 FilterChainProxy，它會把請求代理到Spring Security 自己維護的多個過濾鏈，每個過濾鏈會匹配一些URL，如果匹配則執行對應的過濾器。過濾鍊是有順序的，一個請求只會執行第一個符合的過濾鏈。 Spring Security 的配置本質上就是新增、刪除、修改過濾器。
預設情況下系統幫我們注入的這 15 個過濾器，分別對應配置不同的需求。接下來我們重點是分析下 UsernamePasswordAuthenticationFilter 這個過濾器，他是用來使用使用者名稱和密碼登入認證的過濾器，但是很多情況下我們的登入不只簡單的使用者名稱和密碼，又可能是用到第三方授權登入，這個時候我們就需要使用自訂過濾器，當然這裡不做詳細說明，只是說下自訂過濾器怎麼注入。
@Override
protected void configure(HttpSecurity http) throws Exception {
http.addFilterAfter(...);
...
}在開始身分認證流程之前我們需要先了解下幾個基本概念
SecurityContext context = SecurityContextHolder.getContext(); Authentication authentication = context.getAuthentication();
public interface Authentication extends Principal, Serializable {
//获取用户权限，一般情况下获取到的是用户的角色信息
Collection extends GrantedAuthority> getAuthorities();
//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
Object getCredentials();
//获取用户的额外信息，比如 IP 地址、经纬度等
Object getDetails();
//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)
Object getPrincipal();
//获取当前 Authentication 是否已认证
boolean isAuthenticated();
//设置当前 Authentication 是否已认证
void setAuthenticated(boolean isAuthenticated);
}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);
}public interface UserDetailsService {
//根据用户名查到对应的 UserDetails 对象
UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;
}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, 由下面 5.3 详解
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) {
//认证失败调用...由下面 5.1 详解
unsuccessfulAuthentication(request, response, failed);
return;
}
catch (AuthenticationException failed) {
//认证失败调用...由下面 5.1 详解
unsuccessfulAuthentication(request, response, failed);
return;
}
// Authentication success
if (continueChainBeforeSuccessfulAuthentication) {
chain.doFilter(request, response);
}
//认证成功调用...由下面 5.2 详解
successfulAuthentication(request, response, chain, authResult);
}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);
}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);
}
}
}
}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);
}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);
}
}public class ProviderManager implements AuthenticationManager, MessageSourceAware,
InitializingBean {
...
private List<authenticationprovider> 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;
}
}</authenticationprovider>DaoAuthenticationProvider
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
// 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();
}
//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);
}
}本篇文章到这里就已经全部结束了，更多其他精彩内容可以关注PHP中文网的Java教程视频栏目！
以上是Spring Security原理的介紹（附程式碼）的詳細內容。更多資訊請關注PHP中文網其他相關文章！
