欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识！
您现在的位置是： 首页

Comparison method violates its general contract

程序员文章站 2024-02-23 08:05:46
...

一.项目需求

项目中资源管理模块需要展示服务器资源列表:即以树结构形式按一定规则排序展示指定服务器所有目录以及文件

二.项目背景

容器采用tomcat,jdk8,服务一直运行正常

后来进行服务漏洞补丁升级,tomcat更换为undertow

升级后出现异常,所有服务器的部分资源无法显示

三.具体错误

如下所示:

{
	"msg": "java.lang.IllegalArgumentException: Comparison method violates its general contract!
	at java.util.TimSort.mergeHi(TimSort.java:899)
	at java.util.TimSort.mergeAt(TimSort.java:516)
	at java.util.TimSort.mergeForceCollapse(TimSort.java:457)
	at java.util.TimSort.sort(TimSort.java:254)
	at java.util.Arrays.sort(Arrays.java:1438)
	at net.*.TemplateAction.showChildFileAndFolder(TemplateAction.java:231)
	at net.*.TemplateAction$$FastClassBySpringCGLIB$$2c0e26aa.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.apache.shiro.spring.security.interceptor.AopAllianceAnnotationsAuthorizingMethodInterceptor$1.proceed(AopAllianceAnnotationsAuthorizingMethodInterceptor.java:82)
	at org.apache.shiro.authz.aop.AuthorizingMethodInterceptor.invoke(AuthorizingMethodInterceptor.java:39)
	at org.apache.shiro.spring.security.interceptor.AopAllianceAnnotationsAuthorizingMethodInterceptor.invoke(AopAllianceAnnotationsAuthorizingMethodInterceptor.java:115)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689)
	at net.*.TemplateAction$$EnhancerBySpringCGLIB$$37632c32.showChildFileAndFolder(<generated>)
	at sun.reflect.GeneratedMethodAccessor513.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:503)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:590)
	at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
	at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61)
	at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
	at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
	at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
	at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
	at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
	at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
	at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:123)
	at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
	at org.springframework.session.web.http.SessionRepositoryFilter.doFilterInternal(SessionRepositoryFilter.java:141)
	at org.springframework.session.web.http.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:82)
	at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
	at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
	at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
	at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
	at io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
	at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
	at io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
	at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:132)
	at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
	at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
	at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
	at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
	at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
	at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
	at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
	at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
	at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
	at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:269)
	at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:78)
	at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:133)
	at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:130)
	at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
	at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
	at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:249)
	at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:78)
	at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:99)
	at io.undertow.server.Connectors.executeRootHandler(Connectors.java:376)
	at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)",
	"result": false,
	"exc": "java.lang.IllegalArgumentException",
	"code": 500,
	"cls": "java.util.TimSort.mergeHi(TimSort.java:899)",
	"url": "path/showChildFileAndFolder"
}

抛出错误:Comparison method violates its general contract!

四.查看源码

    at java.util.TimSort.mergeHi(TimSort.java:899)
	at java.util.TimSort.mergeAt(TimSort.java:516)
	at java.util.TimSort.mergeForceCollapse(TimSort.java:457)
	at java.util.TimSort.sort(TimSort.java:254)
	at java.util.Arrays.sort(Arrays.java:1438)

追查下去发现

     /** 
     * @throws IllegalArgumentException (optional) if the comparator is
     *         found to violate the {@link Comparator} contract
     */
    public static <T> void sort(T[] a, Comparator<? super T> c) {
        if (c == null) {
            sort(a);
        } else {
            if (LegacyMergeSort.userRequested)
                legacyMergeSort(a, c);
            else
                TimSort.sort(a, 0, a.length, c, null, 0, 0);
        }
    }

Collections.sort方法指定一个比较器,查看注释发现当比较器不合法时会抛出IllegalArgumentException异常,进入else代码段调用TimSort.sort方法()

五.查看业务代码

 Arrays.sort(files, new TemplateAction.CompareByLastModified());

此处贴出关键错误代码,省略业务逻辑和非关键校验

   //根据资源文件修改时间进行比较的内部类
   static class CompareByLastModified implements Comparator<File> {
      public int compare(File f1, File f2) {
         if (f1.isFile() && f2.isFile()){
            long diff = f1.lastModified() - f2.lastModified();
            if (diff > 0) {
               return 1;
            } else if (diff == 0) {
               return 0;
            } else {
               return -1;
            }
         }else {
            return 0;
         }
      }
   }

修改正确代码

    static class CompareByLastModified implements Comparator<File> {
      public int compare(File f1, File f2) {
         if(f1 == null && f2 == null){
            return 0;
         }
         if(f1 == null){
            return -1;
         }
         if(f2 == null){
            return 1;
         }
         if (f1.isFile() && f2.isFile()){
            long diff = f1.lastModified() - f2.lastModified();
            if (diff > 0) {
               return 1;
            } else if (diff == 0) {
               return 0;
            } else {
               return -1;
            }
         }else {
            return 0;
         }
      }
   }

六.总结

自定义比较器需要注意比较集合是否是可比较的对象

同时需要注意比较对象是否合法,compare(o1,o2)方法返回[-1,0,1],如果返回null则不合法会导致出错,需要判断比较对象object的合法性

相关标签： 解决方案 java 后端

上一篇： systemctl 编辑器更改为 vim

下一篇： Android开发之Retrofit小试牛刀

推荐阅读