今天來和小伙伴們聊一聊 Spring Security 中的異常處理機(jī)制雄卷。
在 Spring Security 的過濾器鏈中，ExceptionTranslationFilter 過濾器專門用來處理異常蛤售，在 ExceptionTranslationFilter 中丁鹉，我們可以看到，異常被分為了兩大類：認(rèn)證異常和授權(quán)異常悴能，兩種異常分別由不同的回調(diào)函數(shù)來處理揣钦，今天松哥就來和大家分享一下這里的條條框框。
1.異常分類
Spring Security 中的異衬穑可以分為兩大類冯凹，一種是認(rèn)證異常，一種是授權(quán)異常炒嘲。
認(rèn)證異常就是 AuthenticationException宇姚，它有眾多的實(shí)現(xiàn)類：
可以看到，這里的異常實(shí)現(xiàn)類還是蠻多的夫凸，都是都是認(rèn)證相關(guān)的異常浑劳，也就是登錄失敗的異常。這些異常寸痢，有的松哥在之前的文章中都和大家介紹過了，例如下面這段代碼(節(jié)選自：Spring Security 做前后端分離啼止，咱就別做頁(yè)面跳轉(zhuǎn)了！統(tǒng)統(tǒng) JSON 交互)：
resp.setContentType("application/json;charset=utf-8");
PrintWriter out = resp.getWriter();
RespBean respBean = RespBean.error(e.getMessage());
if (e instanceof LockedException) {
respBean.setMsg("賬戶被鎖定滓窍，請(qǐng)聯(lián)系管理員!");
} else if (e instanceof CredentialsExpiredException) {
respBean.setMsg("密碼過期，請(qǐng)聯(lián)系管理員!");
} else if (e instanceof AccountExpiredException) {
respBean.setMsg("賬戶過期巩那，請(qǐng)聯(lián)系管理員!");
} else if (e instanceof DisabledException) {
respBean.setMsg("賬戶被禁用吏夯，請(qǐng)聯(lián)系管理員!");
} else if (e instanceof BadCredentialsException) {
respBean.setMsg("用戶名或者密碼輸入錯(cuò)誤，請(qǐng)重新輸入!");
}
out.write(new ObjectMapper().writeValueAsString(respBean));
out.flush();
out.close();
另一類就是授權(quán)異常 AccessDeniedException裆赵，授權(quán)異常的實(shí)現(xiàn)類比較少，因?yàn)槭跈?quán)失敗的可能原因比較少跺嗽。
2.ExceptionTranslationFilter
ExceptionTranslationFilter 是 Spring Security 中專門負(fù)責(zé)處理異常的過濾器战授，默認(rèn)情況下，這個(gè)過濾器已經(jīng)被自動(dòng)加載到過濾器鏈中植兰。
有的小伙伴可能不清楚是怎么被加載的璃吧，我這里和大家稍微說一下。
當(dāng)我們使用 Spring Security 的時(shí)候畜挨，如果需要自定義實(shí)現(xiàn)邏輯，都是繼承自 WebSecurityConfigurerAdapter 進(jìn)行擴(kuò)展膝晾，WebSecurityConfigurerAdapter 中本身就進(jìn)行了一部分的初始化操作，我們來看下它里邊 HttpSecurity 的初始化過程：
protected final HttpSecurity getHttp() throws Exception {
if (http != null) {
return http;
}
AuthenticationEventPublisher eventPublisher = getAuthenticationEventPublisher();
localConfigureAuthenticationBldr.authenticationEventPublisher(eventPublisher);
AuthenticationManager authenticationManager = authenticationManager();
authenticationBuilder.parentAuthenticationManager(authenticationManager);
Map<Class<?>, Object> sharedObjects = createSharedObjects();
http = new HttpSecurity(objectPostProcessor, authenticationBuilder,
sharedObjects);
if (!disableDefaults) {
http
.csrf().and()
.addFilter(new WebAsyncManagerIntegrationFilter())
.exceptionHandling().and()
.headers().and()
.sessionManagement().and()
.securityContext().and()
.requestCache().and()
.anonymous().and()
.servletApi().and()
.apply(new DefaultLoginPageConfigurer<>()).and()
.logout();
ClassLoader classLoader = this.context.getClassLoader();
List<AbstractHttpConfigurer> defaultHttpConfigurers =
SpringFactoriesLoader.loadFactories(AbstractHttpConfigurer.class, classLoader);
for (AbstractHttpConfigurer configurer : defaultHttpConfigurers) {
http.apply(configurer);
}
}
configure(http);
return http;
}
可以看到，在 getHttp 方法的最后禀忆，調(diào)用了 configure(http);，我們?cè)谑褂?Spring Security 時(shí)离熏，自定義配置類繼承自 WebSecurityConfigurerAdapter 并重寫的 configure(HttpSecurity http) 方法就是在這里調(diào)用的戴涝，換句話說，當(dāng)我們?nèi)ヅ渲?HttpSecurity 時(shí)啥刻，其實(shí)它已經(jīng)完成了一波初始化了。
在默認(rèn)的 HttpSecurity 初始化的過程中娄涩，調(diào)用了 exceptionHandling 方法映跟，這個(gè)方法會(huì)將 ExceptionHandlingConfigurer 配置進(jìn)來扬虚，最終調(diào)用 ExceptionHandlingConfigurer#configure 方法將 ExceptionTranslationFilter 添加到 Spring Security 過濾器鏈中。
我們來看下 ExceptionHandlingConfigurer#configure 方法源碼：
@Override
public void configure(H http) {
AuthenticationEntryPoint entryPoint = getAuthenticationEntryPoint(http);
ExceptionTranslationFilter exceptionTranslationFilter = new ExceptionTranslationFilter(
entryPoint, getRequestCache(http));
AccessDeniedHandler deniedHandler = getAccessDeniedHandler(http);
exceptionTranslationFilter.setAccessDeniedHandler(deniedHandler);
exceptionTranslationFilter = postProcess(exceptionTranslationFilter);
http.addFilter(exceptionTranslationFilter);
}
可以看到球恤，這里構(gòu)造了兩個(gè)對(duì)象傳入到 ExceptionTranslationFilter 中：
- AuthenticationEntryPoint 這個(gè)用來處理認(rèn)證異常辜昵。
- AccessDeniedHandler 這個(gè)用來處理授權(quán)異常碎捺。
具體的處理邏輯則在 ExceptionTranslationFilter 中，我們來看一下：
public class ExceptionTranslationFilter extends GenericFilterBean {
public ExceptionTranslationFilter(AuthenticationEntryPoint authenticationEntryPoint,
RequestCache requestCache) {
this.authenticationEntryPoint = authenticationEntryPoint;
this.requestCache = requestCache;
}
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
try {
chain.doFilter(request, response);
}
catch (IOException ex) {
throw ex;
}
catch (Exception ex) {
Throwable[] causeChain = throwableAnalyzer.determineCauseChain(ex);
RuntimeException ase = (AuthenticationException) throwableAnalyzer
.getFirstThrowableOfType(AuthenticationException.class, causeChain);
if (ase == null) {
ase = (AccessDeniedException) throwableAnalyzer.getFirstThrowableOfType(
AccessDeniedException.class, causeChain);
}
if (ase != null) {
if (response.isCommitted()) {
throw new ServletException("Unable to handle the Spring Security Exception because the response is already committed.", ex);
}
handleSpringSecurityException(request, response, chain, ase);
}
else {
if (ex instanceof ServletException) {
throw (ServletException) ex;
}
else if (ex instanceof RuntimeException) {
throw (RuntimeException) ex;
}
throw new RuntimeException(ex);
}
}
}
private void handleSpringSecurityException(HttpServletRequest request,
HttpServletResponse response, FilterChain chain, RuntimeException exception)
throws IOException, ServletException {
if (exception instanceof AuthenticationException) {
sendStartAuthentication(request, response, chain,
(AuthenticationException) exception);
}
else if (exception instanceof AccessDeniedException) {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if (authenticationTrustResolver.isAnonymous(authentication) || authenticationTrustResolver.isRememberMe(authentication)) {
sendStartAuthentication(
request,
response,
chain,
new InsufficientAuthenticationException(
messages.getMessage(
"ExceptionTranslationFilter.insufficientAuthentication",
"Full authentication is required to access this resource")));
}
else {
accessDeniedHandler.handle(request, response,
(AccessDeniedException) exception);
}
}
}
protected void sendStartAuthentication(HttpServletRequest request,
HttpServletResponse response, FilterChain chain,
AuthenticationException reason) throws ServletException, IOException {
SecurityContextHolder.getContext().setAuthentication(null);
requestCache.saveRequest(request, response);
logger.debug("Calling Authentication entry point.");
authenticationEntryPoint.commence(request, response, reason);
}
}
ExceptionTranslationFilter 的源碼比較長(zhǎng)优构，我這里列出來核心的部分和大家分析：
- 過濾器最核心的當(dāng)然是 doFilter 方法，我們就從 doFilter 方法看起拧额。這里的 doFilter 方法中過濾器鏈繼續(xù)向下執(zhí)行彪腔，ExceptionTranslationFilter 處于 Spring Security 過濾器鏈的倒數(shù)第二個(gè)，最后一個(gè)是 FilterSecurityInterceptor德挣，F(xiàn)ilterSecurityInterceptor 專門處理授權(quán)問題，在處理授權(quán)問題時(shí)番挺，就會(huì)發(fā)現(xiàn)用戶未登錄屯掖、未授權(quán)等，進(jìn)而拋出異常贴铜，拋出的異常，最終會(huì)被 ExceptionTranslationFilter#doFilter 方法捕獲徘意。
- 當(dāng)捕獲到異常之后陷嘴，接下來通過調(diào)用
throwableAnalyzer.getFirstThrowableOfType方法來判斷是認(rèn)證異常還是授權(quán)異常，判斷出異常類型之后邑退，進(jìn)入到 handleSpringSecurityException 方法進(jìn)行處理；如果不是 Spring Security 中的異常類型地技，則走 ServletException 異常類型的處理邏輯。 - 進(jìn)入到 handleSpringSecurityException 方法之后飒硅，還是根據(jù)異常類型判斷作谚，如果是認(rèn)證相關(guān)的異常，就走 sendStartAuthentication 方法妹懒，最終被 authenticationEntryPoint.commence 方法處理；如果是授權(quán)相關(guān)的異常会前，就走 accessDeniedHandler.handle 方法進(jìn)行處理匾竿。
AuthenticationEntryPoint 的默認(rèn)實(shí)現(xiàn)類是 LoginUrlAuthenticationEntryPoint，因此默認(rèn)的認(rèn)證異常處理邏輯就是 LoginUrlAuthenticationEntryPoint#commence 方法岭妖，如下：
public void commence(HttpServletRequest request, HttpServletResponse response,
AuthenticationException authException) throws IOException, ServletException {
String redirectUrl = null;
if (useForward) {
if (forceHttps && "http".equals(request.getScheme())) {
redirectUrl = buildHttpsRedirectUrlForRequest(request);
}
if (redirectUrl == null) {
String loginForm = determineUrlToUseForThisRequest(request, response,
authException);
RequestDispatcher dispatcher = request.getRequestDispatcher(loginForm);
dispatcher.forward(request, response);
return;
}
}
else {
redirectUrl = buildRedirectUrlToLoginPage(request, response, authException);
}
redirectStrategy.sendRedirect(request, response, redirectUrl);
}
可以看到区转，就是重定向，重定向到登錄頁(yè)面（即當(dāng)我們未登錄就去訪問一個(gè)需要登錄才能訪問的資源時(shí)废离，會(huì)自動(dòng)重定向到登錄頁(yè)面）。
AccessDeniedHandler 的默認(rèn)實(shí)現(xiàn)類則是 AccessDeniedHandlerImpl悼尾，所以授權(quán)異常默認(rèn)是在 AccessDeniedHandlerImpl#handle 方法中處理的：
public void handle(HttpServletRequest request, HttpServletResponse response,
AccessDeniedException accessDeniedException) throws IOException,
ServletException {
if (!response.isCommitted()) {
if (errorPage != null) {
request.setAttribute(WebAttributes.ACCESS_DENIED_403,
accessDeniedException);
response.setStatus(HttpStatus.FORBIDDEN.value());
RequestDispatcher dispatcher = request.getRequestDispatcher(errorPage);
dispatcher.forward(request, response);
}
else {
response.sendError(HttpStatus.FORBIDDEN.value(),
HttpStatus.FORBIDDEN.getReasonPhrase());
}
}
}
可以看到肖方，這里就是服務(wù)端跳轉(zhuǎn)返回 403俯画。
3.自定義處理
前面和大家介紹了 Spring Security 中默認(rèn)的處理邏輯析桥，實(shí)際開發(fā)中，我們可以需要做一些調(diào)整埋虹，很簡(jiǎn)單娩怎，在 exceptionHandling 上進(jìn)行配置即可。
首先自定義認(rèn)證異常處理類和授權(quán)異常處理類：
@Component
public class MyAuthenticationEntryPoint implements AuthenticationEntryPoint {
@Override
public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException {
response.getWriter().write("login failed:" + authException.getMessage());
}
}
@Component
public class MyAccessDeniedHandler implements AccessDeniedHandler {
@Override
public void handle(HttpServletRequest request, HttpServletResponse response, AccessDeniedException accessDeniedException) throws IOException, ServletException {
response.setStatus(403);
response.getWriter().write("Forbidden:" + accessDeniedException.getMessage());
}
}
然后在 SecurityConfig 中進(jìn)行配置爬泥，如下：
@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http.authorizeRequests()
...
...
.and()
.exceptionHandling()
.authenticationEntryPoint(myAuthenticationEntryPoint)
.accessDeniedHandler(myAccessDeniedHandler)
.and()
...
...
}
}
配置完成后崩瓤，重啟項(xiàng)目，認(rèn)證異常和授權(quán)異常就會(huì)走我們自定義的邏輯了葬馋。
4.小結(jié)
好啦肾扰，今天主要和小伙伴們分享了 Spring Security 中的異常處理機(jī)制蛋逾，感興趣的小伙伴可以試一試哦～
文中代碼下載地址：https://github.com/lenve/spring-security-samples
公眾號(hào)【江南一點(diǎn)雨】后臺(tái)回復(fù) springsecurity，獲取Spring Security 系列 40+ 篇完整文章～
