SpringSecurity 初始化流程源码
SpringSecurity 初始化流程源码
本篇主要讲解 SpringSecurity初始化流程的源码部分，包括核心的 springSecurityFilterChain 是如何创建的，以及在介绍哪里可以扩展个性化的配置，SpringSecurity源码其实是蛮难得 各种Builder Configure 看得真的头疼！
1.简单介绍
SpringSecurity 的核心功能主要包括：
认证 （你是谁）
授权 （你能干什么）
攻击防护 （防止伪造身份）
其核心就是一组过滤器链，项目启动后将会自动配置,本篇也会涉及过滤器链是如何自动初始化的。
SecurityContextPersistenceFilter 是最前面的一个filter
请求到它时候会去检查 根据sessionId找到session 判断session 中是否存在 SecurityContext 在 则将 SecurityContext 存入当前的线程中去
响应的时候，看当前线程是否有SecurityContext ，如果有 放入到session中去 这样不同的请求都能拿到相同的 用户认证信息。
UsernamePasswordAuthenticationFilter 该过滤器是处理表单登录的，通过表单登录提交的认证都会经过它处理
SocialAuthenticationFilter 比如这个就是社交登录使用的Filter
详细可以看我另外一篇 SpringSocial 实现第三方QQ登录SpringSocial 实现第三方QQ登录
绿色的过滤器都是可配置的，其他颜色的都不行！
2.SecurityAutoConfiguration
如果是SpringBoot项目只要你依赖了SpringSecurity相关依赖依然会有自动配置类
SecurityAutoConfiguration 生效 它会导入 WebSecurityEnableConfiguration
@EnableWebSecurity将会是我们本篇的主要切入点
3.@EnableWebSecurity注解介绍
该注解 它是初始化Spring Security的入口 .
打开@EnableWebSecurity注解
@Retention(value = java.lang.annotation.RetentionPolicy.RUNTIME)
@Target(value = { java.lang.annotation.ElementType.TYPE })
@Documented
@Import({ WebSecurityConfiguration.class,
SpringWebMvcImportSelector.class,
OAuth2ImportSelector.class })
@EnableGlobalAuthentication
@Configuration
public @interface EnableWebSecurity {
/**
* Controls debugging support for Spring Security. Default is false.
* @return if true, enables debug support with Spring Security
*/
boolean debug() default false;
}
该注解类通过@Configuration和@Import配合使用引入了一个配置类（WebSecurityConfiguration）和两个ImportSelector（SpringWebMvcImportSelector，OAuth2ImportSelector），我们重点关注下WebSecurityConfiguration，它是Spring Security的核心
4.springSecurityFilterChain初始化流程及源码
打开WebSecurityConfiguration 它是一个配置类，主要看 springSecurityFilterChain()方法,它就是初始化
springSecurityFilterChain的核心方法
/**
* Creates the Spring Security Filter Chain
* @return the {@link Filter} that represents the security filter chain
* @throws Exception
*/
@Bean(name = AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)
public Filter springSecurityFilterChain() throws Exception {
boolean hasConfigurers = webSecurityConfigurers != null
&& !webSecurityConfigurers.isEmpty();
if (!hasConfigurers) {
WebSecurityConfigurerAdapter adapter = objectObjectPostProcessor
.postProcess(new WebSecurityConfigurerAdapter() {
});
webSecurity.apply(adapter);
}
return webSecurity.build();
}
@Bean注解name属性值AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME就是XML中定义的springSecurityFilterChain
从源码中知道过滤器通过最后的 webSecurity.build()创建，webSecurity的类型为：WebSecurity，它在 setFilterChainProxySecurityConfigurer方法中优先被创建了：
@Autowired(required = false)
public void setFilterChainProxySecurityConfigurer(
ObjectPostProcessor<Object> objectPostProcessor,
@Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}") List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers)
throws Exception {
webSecurity = objectPostProcessor
.postProcess(new WebSecurity(objectPostProcessor));
if (debugEnabled != null) {
webSecurity.debug(debugEnabled);
}
webSecurityConfigurers.sort(AnnotationAwareOrderComparator.INSTANCE);
Integer previousOrder = null;
Object previousConfig = null;
for (SecurityConfigurer<Filter, WebSecurity> config : webSecurityConfigurers) {
Integer order = AnnotationAwareOrderComparator.lookupOrder(config);
if (previousOrder != null && previousOrder.equals(order)) {
throw new IllegalStateException(
"@Order on WebSecurityConfigurers must be unique. Order of "
+ order + " was already used on " + previousConfig + ", so it cannot be used on "
+ config + " too.");
}
previousOrder = order;
previousConfig = config;
}
for (SecurityConfigurer<Filter, WebSecurity> webSecurityConfigurer : webSecurityConfigurers) {
webSecurity.apply(webSecurityConfigurer);
}
this.webSecurityConfigurers = webSecurityConfigurers;
}
从代码中可以看到，它是直接被new出来的：
webSecurity = objectPostProcessor
.postProcess(new WebSecurity(objectPostProcessor));
setFilterChainProxySecurityConfigurer 该方法的webSecurityConfigurers 参数是通过@Value注入的
@Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}")
AutowiredWebSecurityConfigurersIgnoreParents的 getWebSecurityConfigurers()
如下，就是获取所有的 WebSecurityConfigurer的类型的配置类
而通常 我们通过继承 WebSecurityConfigurerAdapter 来自定义WebSecurityConfigurer
public List<SecurityConfigurer<Filter, WebSecurity>> getWebSecurityConfigurers() {
List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers = new ArrayList<>();
Map<String, WebSecurityConfigurer> beansOfType = beanFactory
.getBeansOfType(WebSecurityConfigurer.class);
for (Entry<String, WebSecurityConfigurer> entry : beansOfType.entrySet()) {
webSecurityConfigurers.add(entry.getValue());
}
return webSecurityConfigurers;
}
再回到setFilterChainProxySecurityConfigurer方法 下面有一段这样的代码 ，对于上面获取的所有的WebSecurityConfigurer类型 循环执行 webSecurity的apply方法
for (SecurityConfigurer<Filter, WebSecurity> webSecurityConfigurer : webSecurityConfigurers) {
webSecurity.apply(webSecurityConfigurer);
}
webSecurity集成AbstractConfiguredSecurityBuilder 它提供apply方法 再其内部调用add方法
public <C extends SecurityConfigurer<O, B>> C apply(C configurer) throws Exception {
add(configurer);
return configurer;
}
add(configurer)，主要就是将其传入的WebSecurityConfigurer存入到 LinkedHashMap configures中，
主要代码 this.configurers.put(clazz, configs);
private <C extends SecurityConfigurer<O, B>> void add(C configurer) {
Assert.notNull(configurer, "configurer cannot be null");
Class<? extends SecurityConfigurer<O, B>> clazz = (Class<? extends SecurityConfigurer<O, B>>) configurer
.getClass();
synchronized (configurers) {
if (buildState.isConfigured()) {
throw new IllegalStateException("Cannot apply " + configurer
+ " to already built object");
}
List<SecurityConfigurer<O, B>> configs = allowConfigurersOfSameType ? this.configurers
.get(clazz) : null;
if (configs == null) {
configs = new ArrayList<>(1);
}
configs.add(configurer);
this.configurers.put(clazz, configs);
if (buildState.isInitializing()) {
this.configurersAddedInInitializing.add(configurer);
}
}
}
当所有的 WebSecurityConfigurer 类型的配置 全部应用到 WebSecurity中去后 setFilterChainProxySecurityConfigurer方法也就结束了
回到创建过滤器链的方法 springSecurityFilterChain()
它会判断我们刚刚的webSecurityConfigurers是否存在，不存在就新建一个，然后执行 webSecurity.build() 重要！
@Bean(name = AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)
public Filter springSecurityFilterChain() throws Exception {
boolean hasConfigurers = webSecurityConfigurers != null
&& !webSecurityConfigurers.isEmpty();
if (!hasConfigurers) {
WebSecurityConfigurerAdapter adapter = objectObjectPostProcessor
.postProcess(new WebSecurityConfigurerAdapter() {
});
webSecurity.apply(adapter);
}
return webSecurity.build();
}
最终内部会有下面这段代码， 主要关注 init() configure() 和 performBuild() 这三个方法
@Override
protected final O doBuild() throws Exception {
synchronized (configurers) {
buildState = BuildState.INITIALIZING;
beforeInit();
init();
buildState = BuildState.CONFIGURING;
beforeConfigure();
configure();
buildState = BuildState.BUILDING;
O result = performBuild();
buildState = BuildState.BUILT;
return result;
}
}
init() 内部循环遍历 所有的 WebSecurityConfigurer ,它会执行到 WebSecurityConfigurerAdapter的
private void init() throws Exception {
Collection<SecurityConfigurer<O, B>> configurers = getConfigurers();
for (SecurityConfigurer<O, B> configurer : configurers) {
configurer.init((B) this);
}
for (SecurityConfigurer<O, B> configurer : configurersAddedInInitializing) {
configurer.init((B) this);
}
}
configurer.init((B) this)
它只要完成两件重要的事情：
初始化HttpSecurity对象(注意它和WebSecurity不一样 )；
设置HttpSecurity对象添加至WebSecurity的securityFilterChainBuilders列表中；
public void init(final WebSecurity web) throws Exception {
final HttpSecurity http = getHttp();
web.addSecurityFilterChainBuilder(http).postBuildAction(() -> {
FilterSecurityInterceptor securityInterceptor = http
.getSharedObject(FilterSecurityInterceptor.class);
web.securityInterceptor(securityInterceptor);
});
}
初始化HttpSecurity对象在getHttp()方法中实现：
protected final HttpSecurity getHttp() throws Exception {
if (http != null) {
return http;
}
DefaultAuthenticationEventPublisher eventPublisher = objectPostProcessor
.postProcess(new DefaultAuthenticationEventPublisher());
localConfigureAuthenticationBldr.authenticationEventPublisher(eventPublisher);
AuthenticationManager authenticationManager = authenticationManager();
authenticationBuilder.parentAuthenticationManager(authenticationManager);
authenticationBuilder.authenticationEventPublisher(eventPublisher);
Map<Class<?>, Object> sharedObjects = createSharedObjects();
http = new HttpSecurity(objectPostProcessor, authenticationBuilder,
sharedObjects);
if (!disableDefaults) {
// @formatter:off
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();
// @formatter:on
ClassLoader classLoader = this.context.getClassLoader();
List<AbstractHttpConfigurer> defaultHttpConfigurers =
SpringFactoriesLoader.loadFactories(AbstractHttpConfigurer.class, classLoader);
for (AbstractHttpConfigurer configurer : defaultHttpConfigurers) {
http.apply(configurer);
}
}
configure(http);
return http;
}
从代码中可以了解，HttpSecurity是直接被new出来的，在创建HttpSecurity之前，首先初始化了AuthenticationManagerBuilder对象，这里有段代码很重要就是： AuthenticationManager authenticationManager = authenticationManager();，它创建AuthenticationManager实例，打开authenticationManager()方法：
默认实现是在 WebSecurityConfigurerAdapter 中
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
this.disableLocalConfigureAuthenticationBldr = true;
}
1、个性化配置入口之configure(AuthenticationManagerBuilder auth)
我们可以通过继承WebSecurityConfigurerAdapter并重写该方法来个性化配置AuthenticationManagerBuilder。
如下是自己继承WebSecurityConfigurerAdapter 重写 configure(AuthenticationManagerBuilder auth)，实现个性化的第一个配置入口
/**
* @author johnny
* @create 2020-01-18 下午6:40
**/
@Configuration
@Slf4j
public class MyWebSecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
super.configure(auth);
log.info("【测试 定制化入口 configure(AuthenticationManagerBuilder auth) 的执行 】");
}
}
构建完HttpSecurity实例后，默认情况下会添加默认的拦截其配置：
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();
我挑一个默认的方法展开看一下比如 会话管理的sessionManagement(),内部就是去创建SessionManagementConfigurer并应用它
public SessionManagementConfigurer<HttpSecurity> sessionManagement() throws Exception {
return getOrApply(new SessionManagementConfigurer<>());
}
getOrApply 最有一句代码 return apply(configurer);
private <C extends SecurityConfigurerAdapter<DefaultSecurityFilterChain, HttpSecurity>> C getOrApply(
C configurer) throws Exception {
C existingConfig = (C) getConfigurer(configurer.getClass());
if (existingConfig != null) {
return existingConfig;
}
return apply(configurer);
}
apply(configurer) 注意这里的 configurer传入的是SessionManagementConfigurer
public <C extends SecurityConfigurerAdapter<O, B>> C apply(C configurer)
throws Exception {
configurer.addObjectPostProcessor(objectPostProcessor);
configurer.setBuilder((B) this);
add(configurer);
return configurer;
}
最终又调用了 add(configurer); 这不过这里是给 HttpSecurity的 configurers 配置初始的，上面是配置的WebSecurity的configurers, 不要混淆，最终这些configurers会被一个个创建成 对应的过滤器Filter的 详细在后面有说明
private <C extends SecurityConfigurer<O, B>> void add(C configurer) {
Assert.notNull(configurer, "configurer cannot be null");
Class<? extends SecurityConfigurer<O, B>> clazz = (Class<? extends SecurityConfigurer<O, B>>) configurer
.getClass();
synchronized (configurers) {
if (buildState.isConfigured()) {
throw new IllegalStateException("Cannot apply " + configurer
+ " to already built object");
}
List<SecurityConfigurer<O, B>> configs = allowConfigurersOfSameType ? this.configurers
.get(clazz) : null;
if (configs == null) {
configs = new ArrayList<>(1);
}
configs.add(configurer);
this.configurers.put(clazz, configs);
if (buildState.isInitializing()) {
this.configurersAddedInInitializing.add(configurer);
}
}
}
如下图：为HttpSecurity添加了很多默认的配置
回到 getHttp()方法
最后调用configure(http);，这又是一个可个性化的配置入口，它的默认实现是：WebSecurityConfigurerAdapter提供的
默认的配置是拦截所有的请求需要认证之后才能访问，如果没有认证，会自动生成一个认证表单要求输入用户名和密码。
protected void configure(HttpSecurity http) throws Exception {
logger.debug("Using default configure(HttpSecurity). If subclassed this will potentially override subclass configure(HttpSecurity).");
http
.authorizeRequests()
.anyRequest().authenticated()
.and()
.formLogin().and()
.httpBasic();
}
2、个性化配置入口之configure(HttpSecurity http)
我们可以通过继承WebSecurityConfigurerAdapter并重写该方法来个性化配置HttpSecurity。
OK，目前为止HttpSecurity已经被初始化，接下去需要设置HttpSecurity对象添加至WebSecurity的securityFilterChainBuilders列表中：
public void init(final WebSecurity web) throws Exception {
final HttpSecurity http = getHttp();
web.addSecurityFilterChainBuilder(http).postBuildAction(() -> {
FilterSecurityInterceptor securityInterceptor = http
.getSharedObject(FilterSecurityInterceptor.class);
web.securityInterceptor(securityInterceptor);
});
}
当所有的WebSecurityConfigurer的init方法被调用之后，webSecurity.init()工作就结束了
接下去调用了webSecurity.configure()，该方法同样是在AbstractConfiguredSecurityBuilder中实现的：
private void configure() throws Exception {
Collection<SecurityConfigurer<O, B>> configurers = getConfigurers();
for (SecurityConfigurer<O, B> configurer : configurers) {
configurer.configure((B) this);
}
}
它的主要工作是迭代调用所有WebSecurityConfigurer的configurer方法，参数是WebSeucrity本身，这又是另外一个重要的个性化入口：
3、个性化配置入口之configure(WebSecurity web)
我们可以通过继承WebSecurityConfigurerAdapter并重写该方法来个性化配置WebSecurity。
至此，三个重要的个性化入口都已经被调用，即在实现WebSecurityConfigurerAdapter经常需要重写的：
1、configure(AuthenticationManagerBuilder auth);
2、configure(WebSecurity web);
3、configure(HttpSecurity http);
回到webSecurity构建过程，接下去重要的的调用：
O result = performBuild();
performBuild() 非常重要！！
@Override
protected Filter performBuild() throws Exception {
Assert.state(
!securityFilterChainBuilders.isEmpty(),
() -> "At least one SecurityBuilder<? extends SecurityFilterChain> needs to be specified. "
+ "Typically this done by adding a @Configuration that extends WebSecurityConfigurerAdapter. "
+ "More advanced users can invoke "
+ WebSecurity.class.getSimpleName()
+ ".addSecurityFilterChainBuilder directly");
int chainSize = ignoredRequests.size() + securityFilterChainBuilders.size();
List<SecurityFilterChain> securityFilterChains = new ArrayList<>(
chainSize);
for (RequestMatcher ignoredRequest : ignoredRequests) {
securityFilterChains.add(new DefaultSecurityFilterChain(ignoredRequest));
}
for (SecurityBuilder<? extends SecurityFilterChain> securityFilterChainBuilder : securityFilterChainBuilders) {
securityFilterChains.add(securityFilterChainBuilder.build());
}
FilterChainProxy filterChainProxy = new FilterChainProxy(securityFilterChains);
if (httpFirewall != null) {
filterChainProxy.setFirewall(httpFirewall);
}
filterChainProxy.afterPropertiesSet();
Filter result = filterChainProxy;
if (debugEnabled) {
logger.warn("\n\n"
+ "********************************************************************\n"
+ "********** Security debugging is enabled. *************\n"
+ "********** This may include sensitive information. *************\n"
+ "********** Do not use in a production system! *************\n"
+ "********************************************************************\n\n");
result = new DebugFilter(filterChainProxy);
}
postBuildAction.run();
return result;
}
首先计算出chainSize，也就是ignoredRequests.size() + securityFilterChainBuilders.size();，如果你不配置ignoredRequests，那就是securityFilterChainBuilders.size()，也就是HttpSecurity的个数，其本质上就是你一共配置几个WebSecurityConfigurerAdapter，因为每个WebSecurityConfigurerAdapter对应一个HttpSecurity，而所谓的ignoredRequests就是FilterChainProxy的请求，默认是没有的，如果你需要条跳过某些请求不需要认证或授权，可以如下配置：
@Override
public void configure(WebSecurity web) throws Exception {
web.ignoring().antMatchers("/statics/**");
}
在上面配置中，所有以/statics开头请求都将被FilterChainProxy忽略。
securityFilterChains.add(securityFilterChainBuilder.build()); 这一行就是初始化所有的过滤器，记得上面有段代码如下，将HttpSecurity设置到WebSecurity的 securityFilterChainBuilder中，上面就是调用HttpSecurity.build()方法，初始化所有的 HttpSecurity的过滤器链
public void init(final WebSecurity web) throws Exception {
final HttpSecurity http = getHttp();
web.addSecurityFilterChainBuilder(http).postBuildAction(() -> {
FilterSecurityInterceptor securityInterceptor = http
.getSharedObject(FilterSecurityInterceptor.class);
web.securityInterceptor(securityInterceptor);
});
}
依然来到 doBuild()方法，只不过这次是执行的 HttpSecurity的
@Override
protected final O doBuild() throws Exception {
synchronized (configurers) {
buildState = BuildState.INITIALIZING;
beforeInit();
init();
buildState = BuildState.CONFIGURING;
beforeConfigure();
configure();
buildState = BuildState.BUILDING;
O result = performBuild();
buildState = BuildState.BUILT;
return result;
}
}
重点查看 configure()该方法 会调用对应的 过滤器配置的configure()
如 再内部创建 SessionManagementFilter 最后添加到HttpSecurity中，也就是拿 HttpSecurity的configures 一个个创建出对应的过滤器
@Override
public void configure(H http) {
SecurityContextRepository securityContextRepository = http
.getSharedObject(SecurityContextRepository.class);
SessionManagementFilter sessionManagementFilter = new SessionManagementFilter(
securityContextRepository, getSessionAuthenticationStrategy(http));
if (this.sessionAuthenticationErrorUrl != null) {
sessionManagementFilter.setAuthenticationFailureHandler(
new SimpleUrlAuthenticationFailureHandler(
this.sessionAuthenticationErrorUrl));
}
InvalidSessionStrategy strategy = getInvalidSessionStrategy();
if (strategy != null) {
sessionManagementFilter.setInvalidSessionStrategy(strategy);
}
AuthenticationFailureHandler failureHandler = getSessionAuthenticationFailureHandler();
if (failureHandler != null) {
sessionManagementFilter.setAuthenticationFailureHandler(failureHandler);
}
AuthenticationTrustResolver trustResolver = http
.getSharedObject(AuthenticationTrustResolver.class);
if (trustResolver != null) {
sessionManagementFilter.setTrustResolver(trustResolver);
}
sessionManagementFilter = postProcess(sessionManagementFilter);
http.addFilter(sessionManagementFilter);
if (isConcurrentSessionControlEnabled()) {
ConcurrentSessionFilter concurrentSessionFilter = createConcurrencyFilter(http);
concurrentSessionFilter = postProcess(concurrentSessionFilter);
http.addFilter(concurrentSessionFilter);
}
}
当doBuild()中的 configure();执行完毕后 的会得到如下HttpSecurity可以看到它内部的filters已经全部创建完毕
回到doBuild()方法 该方中有 performBuild() 调用HttpSecurity的 performBuild()，默认实现如下，先对上面所有的过滤器进行排序，使用的是 FilterComparator() 进行排序的，这里不展开了，反正就是会排序成文章开始的那张图上面的顺序
@Override
protected DefaultSecurityFilterChain performBuild() {
filters.sort(comparator);
return new DefaultSecurityFilterChain(requestMatcher, filters);
}
最后返回的是SecurityFilterChain的默认实现DefaultSecurityFilterChain。
构建完所有SecurityFilterChain后，创建最为重要的FilterChainProxy实例，
FilterChainProxy filterChainProxy = new FilterChainProxy(securityFilterChains);
至此Spring Security 初始化完成，包括springSecurityFilterChain初始化，我们通过继承WebSecurityConfigurerAdapter来代达到个性化配置目的，文中提到了三个重要的个性化入口，并且WebSecurityConfigurerAdapter是可以配置多个的，其对应的接口就是会存在多个SecurityFilterChain实例，但是它们人仍然在同一个FilterChainProxy中，通过RequestMatcher来匹配并传入到对应的SecurityFilterChain中执行请求。
5.个性化入口配置（扩展WebSecurityConfigurerAdapter）
重要的个性化入口都是哪里调用的 已经在上面初始化 springSecurityFilterChain 源码中讲解了，这里知识总结一下
1、个性化配置入口之configure(AuthenticationManagerBuilder auth)
我们可以通过继承WebSecurityConfigurerAdapter并重写该方法来个性化配置AuthenticationManagerBuilder。
2、个性化配置入口之configure(HttpSecurity http)
我们可以通过继承WebSecurityConfigurerAdapter并重写该方法来个性化配置HttpSecurity。
3、个性化配置入口之configure(WebSecurity web)
我们可以通过继承WebSecurityConfigurerAdapter并重写该方法来个性化配置WebSecurity。
实现WebSecurityConfigurerAdapter经常需要重写的：
1、configure(AuthenticationManagerBuilder auth);
2、configure(WebSecurity web);
3、configure(HttpSecurity http);
6.总结
本篇主要讲解了
1.SpringBoot对于SpringSecurity的自动配置的支持类SecurityAutoConfiguration，
2.核心注解@EnableWebSecurity
3. SpringSecurity的核心过滤器链 springSecurityFilterChain 的初始化流程的源码
源码部分还是定下心来多看 加油！
个人博客地址： https://www.askajohnny.com 欢迎访问！
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