Spring Security常用过滤器实例解析

Spring Security常用过滤器实例解析

Spring Security常见的15个拦截器

1 . org.springframework.security.web.context.SecurityContextPersistenceFilter

首当其冲的一个过滤器，作用之重要，自不必多言。

SecurityContextPersistenceFilter主要是使用SecurityContextRepository在session中保存或更新一个

SecurityContext，并将SecurityContext给以后的过滤器使用，来为后续filter建立所需的上下文。

SecurityContext中存储了当前用户的认证以及权限信息。

2 . org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter

此过滤器用于集成SecurityContext到Spring异步执行机制中的WebAsyncManager

3 . org.springframework.security.web.header.HeaderWriterFilter

向请求的Header中添加相应的信息,可在http标签内部使用security:headers来控制

4 . org.springframework.security.web.csrf.CsrfFilter

csrf又称跨域请求伪造，SpringSecurity会对所有post请求验证是否包含系统生成的csrf的token信息，

如果不包含，则报错。起到防止csrf攻击的效果。

5. org.springframework.security.web.authentication.logout.LogoutFilter

匹配 URL为/logout的请求，实现用户退出,清除认证信息。

6 . org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter

认证操作全靠这个过滤器，默认匹配URL为/login且必须为POST请求。

7 . org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter

如果没有在配置文件中指定认证页面，则由该过滤器生成一个默认认证页面。

8 . org.springframework.security.web.authentication.ui.DefaultLogoutPageGeneratingFilter

由此过滤器可以生产一个默认的退出登录页面

9 . org.springframework.security.web.authentication.BasicAuthenticationFilter

此过滤器会自动解析HTTP请求中头部名字为Authentication，且以Basic开头的头信息。

10 . org.springframework.security.web.savedrequest.RequestCacheAwareFilter

通过HttpSessionRequestCache内部维护了一个RequestCache，用于缓存HttpServletRequest

11 . org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter

针对ServletRequest进行了一次包装，使得request具有更加丰富的API

12 . org.springframework.security.web.authentication.AnonymousAuthenticationFilter

当SecurityContextHolder中认证信息为空,则会创建一个匿名用户存入到SecurityContextHolder中。

spring security为了兼容未登录的访问，也走了一套认证流程，只不过是一个匿名的身份。

13 . org.springframework.security.web.session.SessionManagementFilter

SecurityContextRepository限制同一用户开启多个会话的数量

14 . org.springframework.security.web.access.ExceptionTranslationFilter

异常转换过滤器位于整个springSecurityFilterChain的后方，用来转换整个链路中出现的异常

15 . org.springframework.security.web.access.intercept.FilterSecurityInterceptor

获取所配置资源访问的授权信息，根据SecurityContextHolder中存储的用户信息来决定其是否有权限。

那么，是不是spring security一共就这么多过滤器呢？答案是否定的！随着spring-security.xml配置的添加，还

会mfcqIuuQ出现新的过滤器。

那么，是不是spring security每次都会加载这些过滤器呢？答案也是否定的！随着spring-security.xml配置的修

改，有些过滤器可能会被去掉。

spring security 过滤器链加载原理

public class DelegatingFilterProxy extends GenericFilterBean {

@Nullable

private String contextAttribute;

@Nullable

private WebApplicationContext webApplicationContext;

@Nullable

private String targetBeanName;

private boolean targetFilterLifecycle;

@Nullable

private volatile Filter delegate;//注：这个过滤器才是真正加载的过滤器

private final Object delegateMonitor;

//注：doFilter才是过滤器的入口，直接从这看！

public void doFilter(ServletRequest request, ServletResponse response, FilterChain

filterChain) throws ServletException, IOException {

Filter delegateToUse = this.delegate;

if (delegateToUse == null) {

synchronized(this.delegateMonitor) {

delegateToUse = this.delegate;

if (delegateToUse == null) {

WebApplicationContext wac = this.findWebApplicationContext();

if (wac == null) {

throw new IllegalStateException("No WebApplicationContext found: no

ContextLoaderListener or DispatcherServlet registered?");

}

//第一步：doFilter中最重要的一步，初始化上面私有过滤器属性delegate

delegateToUse = this.initDelegate(wac);

}

this.delegate = delegateToUse;

}

}

//第三步：执行FilterChainProxy过滤器

this.invokeDelegate(delegateToUsmfcqIuuQe, request, response, filterChain);

}

//第二步：直接看最终加载的过滤器到底是谁

protected Filter initDelegate(WebApplicationContext wac) throws ServletException {

//debug得知targetBeanName为：springSecurityFilterChain

String targetBeanName = this.getTargetBeanName();

Assert.state(targetBeanName != null, "No target bean name set");

//debug得知delegate对象为：FilterChainProxy

Filter delegate = (Filter)wac.getBean(targetBeanName, Filter.class);

if (this.isTargetFilterLifecycle()) {

delegate.init(this.getFilterConfig());

}

return delegate;

}

protected void invokeDelegate(Filter delegate, ServletRequest request, ServletResponse

response, FilterChain filterChain) throws ServletException, IOException {

delegate.doFilter(request, response, filterChain);

}

}

第二步debug结果如下：

由此可知， DelegatingFilterProxy通过springSecurityFilterChain这个名称，得到了一个FilterChainProxy过滤器，

最终在第三步执行了这个过滤器。

FilterChainProxy

public class FilterChainProxy extends GenericFilterBean {

private static final Log logger = LogFactory.getLog(FilterChainProxy.class);

private static final String FILTER_APPLIED =

FilterChainProxy.class.getName().concat(".APPLIED");

private List filterChains;

private FilterChainProxy.FilterChainValidator filterChainValidator;

private HttpFirewall firewall;

//咿！？可以通过一个叫SecurityFilterChain的对象实例化出一个FilterChainProxy对象

//这FilterChainProxy又是何方神圣？会不会是真正的过滤器链对象呢？先留着这个疑问！

public FilterChainProxy(SecurityFilterChain chain) {

this(Arrays.asList(chain));

}

//又是SecurityFilterChain这家伙！嫌疑更大了！

public FilterChainProxy(List filterChains) {

this.filterChainValidator = new FilterChainProxy.NullFilterChainValidator();

this.firewall = new StrictHttpFirewall();

this.filterChains = filterChains;

}

//注：直接从doFilter看

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

boolean clearContext = request.getAttribute(FILTER_APPLIED) == null;

if (clearContext) {

try {

request.setAttribute(FILTER_APPLIED, Boolean.TRUE);

this.doFilterInternal(request, response, chain);

} finally {

SecurityContextHolder.clearContext();

request.removeAttribute(FILTER_APPLIED);

}

} else {

//第一步：具体操作调用下面的doFilterInternal方法了

this.doFilterInternal(request, response, chain);

}

}

private void doFilterInternal(ServletRequest request, ServletResponse response, FilterChain

chain) throws IOException, ServletException {

FirewalledRequest fwRequest =

this.firewall.getFirewalledRequest((HttpServletRequest)request);

HttpServletResponse fwResponse =

this.firewall.getFirewalledResponse((HttpServletResponse)response);

//第二步：封装要执行的过滤器链，那么多过滤器就在这里被封装进去了！

List filters = this.getFilters((HttpServletRequest)fwRequest);

if (filters != null && filters.size() != 0) {

FilterChainProxy.VirtualFilterChain vfc = new

FilterChainProxy.VirtualFilterChain(fwRequest, chain, filters);

//第四步：加载过滤器链

vfc.doFilter(fwRequest, fwResponse);

} else {

if (logger.isDebugEnabled()) {

logger.debug(UrlUtils.buildRequestUrl(fwRequest) + (filters == null ? " has no

matching filters" : " has an empty filter list"));

}

fwRequest.reset();

chain.doFilter(fwRequest, fwResponse);

}

}

private List getFilters(HttpServletRequest request) {

Iterator var2 = this.filterChains.iterator();

//第三步：封装过滤器链到SecurityFilterChain中！

SecurityFilterChain chain;

do {

if (!var2.hasNext()) {

return null;

}

chain = (SecurityFilterChain)var2.next();

} while(!chain.matches(request));

return chain.getFilters();

}

}

SecurityFilterChain

最后看SecurityFilterChain，这是个接口，实现类也只有一个，这才是web.xml中配置的过滤器链对象！

public interface SecurityFilterChain {

boolean matches(HttpServletRequest request);

List getFilters();

}

public final class DefaultSecurityFilterChain implements SecurityFilterChain {

private static final Log logger = LogFactory.getLog(DefaultSecurityFilterChain.class);

private final RequestMatcher requestMatcher;

private final List filters;

public DefaultSecurityFilterChain(RequestMatcher requestMatcher, Filter... filters) {

this(requestMatcher, Arrays.asList(filters));

}

public DefaultSecurityFilterChain(RequestMatcher requestMatcher, List filters) {

logger.info("Creating filter chain: " + requestMatcher + ", " + filters);

this.requestMatcher = requestMatcher;

this.filters = new ArrayList<>(filters);

}

public RequestMatcher getRequestMatcher() {

return requestMatcher;

}

public List getFilters() {

return filters;

}

public boolean matches(HttpServletRequest request) {

return requestMatcher.matches(request);

}

@Override

public String toString() {

return "[ " + requestMatcher + ", " + filters + "]";

}

}

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