如何正确地将总结当前活动会话的类注入自定义OncePerRequestFilter？
当我尝试将以下HttpSessionCollector注入我的自定义过滤器时，结果是底部的堆栈跟踪中显示的NullPointerException：
public class HttpSessionCollector implements HttpSessionListener, ServletContextListener {
private static final Set<HttpSession> sessions = ConcurrentHashMap.newKeySet();
public void sessionCreated(HttpSessionEvent event) {
sessions.add(event.getSession());
}
public void sessionDestroyed(HttpSessionEvent event) {
sessions.remove(event.getSession());
}
public static Set<HttpSession> getSessions() {
return sessions;
}
public void contextCreated(ServletContextEvent event) {
event.getServletContext().setAttribute("HttpSessionCollector.instance", this);
}
public static HttpSessionCollector getCurrentInstance(ServletContext context) {
return (HttpSessionCollector) context.getAttribute("HttpSessionCollector.instance");
}
@Override
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
// TODO Auto-generated method stub
}
}
DiagnoseSessionsFilter无法注入HttpSessionCollector的代码是：
@Component
public class DiagnoseSessionFilter extends OncePerRequestFilter implements ServletContextAware {
@Override
protected void doFilterInternal(HttpServletRequest req, HttpServletResponse res, FilterChain fc)
throws ServletException, IOException {
System.out.println("...........///////////// START OF DiagnoseSessionFilter.doFilterInternal() ///////////...........");
HttpSessionCollector collector = HttpSessionCollector.getCurrentInstance(getServletContext());
Set<HttpSession> sessions = collector.getSessions();
System.out.println("sessions.size() is: " + sessions.size());
for(HttpSession sess : sessions){
System.out.println("sess is: " + sess);
System.out.println("sess.getId() is: " + sess.getId());
}
SecurityContext context = SecurityContextHolder.getContext();
System.out.println("...........///////////// END OF DiagnoseSessionFilter.doFilterInternal() ///////////...........");
fc.doFilter(req, res);
}
}
使用主应用程序类的以下代码摘录中的DiagnoseSessionsFilter将WebSecurityConfigurerAdapter注入Spring Security Filter Chain。但是，此过滤器注入级别可能与OP无关，因为DiagnoseSessionsFilter确实在过滤器链中的正确位置运行。问题在于HttpSessionCollector注入了DiagnoseSessionsFilter。
@SpringBootApplication
@Controller
@SessionAttributes("attrName")
@EnableResourceServer
public class NameOfApplication extends WebMvcConfigurerAdapter {
public static void main(String[] args) {
SpringApplication.run(NameOfApplication.class, args);
}
//lots of other stuff
@Bean
public static DiagnoseSessionFilter diagnoseSessionFilter(){
return new DiagnoseSessionFilter();
}
@Configuration
@Order(-20)
protected static class LoginConfig extends WebSecurityConfigurerAdapter {
@Autowired
private AuthenticationManager authenticationManager;
@Override
protected void configure(HttpSecurity http) throws Exception {
// @formatter:off
http
.addFilterBefore(diagnoseSessionFilter(), SecurityContextPersistenceFilter.class)
.formLogin().loginPage("/login").permitAll()
.and().authorizeRequests().antMatchers("/url/pattern").permitAll()
.and().authorizeRequests().antMatchers("/another/url/pattern").permitAll()
.and().authorizeRequests().anyRequest().authenticated();
// @formatter:on
}
@Override
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
auth.parentAuthenticationManager(authenticationManager);
}
}
//other stuff
}
错误的堆栈跟踪是：
...........///////////// START OF DiagnoseSessionFilter.doFilterInternal() ///////////...........
2016-06-05 14:53:24.572 ERROR 5941 --- [nio-9999-exec-1] o.a.c.c.C.[.[.[.[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [/uaa] threw exception
java.lang.NullPointerException: null
at examine.HttpSessionCollector.getCurrentInstance(HttpSessionCollector.java:34) ~[classes/:na]
at demo.DiagnoseSessionFilter.doFilterInternal(DiagnoseSessionFilter.java:30) ~[classes/:na]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53) ~[spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213) ~[spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176) ~[spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) ~[tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) [tomcat-embed-core-8.0.32.jar:8.0.32]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) [tomcat-embed-core-8.0.32.jar:8.0.32]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_45]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_45]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.32.jar:8.0.32]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_45]
注意：此OP中的方法是从@BalusC's answer to this other question.
修改的