今天用maven建立web 工程，分別用Tomcat6，Tomcat7啟動，都報錯org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool。最後換成Tomcat8，啟動專案就好了，這應該是tomcat 的一個缺陷。解決問題就是換成高版本的Tomcat8，即可。

Tomcat7 報錯資訊如下：
四月 22, 2017 10:08:23 下午 org.apache.catalina.core.AprLifecycleListener init
資訊: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jdk1.8.0_121\bin;C:\D\MyEclipse\tomcat7\apache-tomcat-7.0.8\bin
四月 22, 2017 10:08:24 下午 org.apache.coyote.AbstractProtocolHandler init
資訊: Initializing ProtocolHandler [“http-bio-8080”]
四月 22, 2017 10:08:24 下午 org.apache.coyote.AbstractProtocolHandler init
資訊: Initializing ProtocolHandler [“ajp-bio-8009”]
四月 22, 2017 10:08:24 下午 org.apache.catalina.startup.Catalina load
資訊: Initialization processed in 3567 ms
四月 22, 2017 10:08:24 下午 org.apache.catalina.core.StandardService startInternal
資訊: Starting service Catalina
四月 22, 2017 10:08:24 下午 org.apache.catalina.core.StandardEngine startInternal
資訊: Starting Servlet Engine: Apache Tomcat/7.0.8
四月 22, 2017 10:08:24 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory docs
四月 22, 2017 10:08:26 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory examples
四月 22, 2017 10:08:28 下午 org.apache.catalina.core.ApplicationContext log
資訊: ContextListener: contextInitialized()
四月 22, 2017 10:08:28 下午 org.apache.catalina.core.ApplicationContext log
資訊: SessionListener: contextInitialized()
四月 22, 2017 10:08:28 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory HelloMaven
四月 22, 2017 10:08:28 下午 org.apache.catalina.loader.WebappClassLoader validateJarFile
資訊: validateJarFile(C:\D\MyEclipse\tomcat7\apache-tomcat-7.0.8\webapps\HelloMaven\WEB-INF\lib\javaee-api-7.0.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
四月 22, 2017 10:08:28 下午 org.apache.catalina.loader.WebappClassLoader validateJarFile
資訊: validateJarFile(C:\D\MyEclipse\tomcat7\apache-tomcat-7.0.8\webapps\HelloMaven\WEB-INF\lib\servlet-api-2.5.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
四月 22, 2017 10:08:29 下午 org.apache.catalina.startup.HostConfig deployDirectory
嚴重: Error deploying web application directory HelloMaven
org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 15
at org.apache.tomcat.util.bcel.classfile.Constant.readConstant(Constant.java:131)
at org.apache.tomcat.util.bcel.classfile.ConstantPool.(ConstantPool.java:60)
at org.apache.tomcat.util.bcel.classfile.ClassParser.readConstantPool(ClassParser.java:209)
at org.apache.tomcat.util.bcel.classfile.ClassParser.parse(ClassParser.java:119)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:1908)
at org.apache.catalina.startup.ContextConfig.processAnnotationsJar(ContextConfig.java:1797)
at org.apache.catalina.startup.ContextConfig.processAnnotationsUrl(ContextConfig.java:1756)
at org.apache.catalina.startup.ContextConfig.processAnnotations(ContextConfig.java:1742)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1245)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:874)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:317)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:89)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4974)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:812)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:787)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:607)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1044)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:967)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:472)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1302)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:89)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:343)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:323)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1043)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1035)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:724)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.startup.Catalina.start(Catalina.java:620)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:304)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
四月 22, 2017 10:08:29 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory host-manager
四月 22, 2017 10:08:29 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory manager
四月 22, 2017 10:08:30 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory ROOT
四月 22, 2017 10:08:30 下午 org.apache.coyote.AbstractProtocolHandler start
資訊: Starting ProtocolHandler [“http-bio-8080”]
四月 22, 2017 10:08:30 下午 org.apache.coyote.AbstractProtocolHandler start
資訊: Starting ProtocolHandler [“ajp-bio-8009”]
四月 22, 2017 10:08:30 下午 org.apache.catalina.startup.Catalina start
資訊: Server startup in 5748 ms

tomcat 8 啟動資訊如下

四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Server version: Apache Tomcat/8.0.43
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Server built: Mar 28 2017 14:42:59 UTC
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Server number: 8.0.43.0
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: OS Name: Windows 10
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: OS Version: 10.0
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Architecture: amd64
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Java Home: C:\Program Files\Java\jdk1.8.0_121\jre
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: JVM Version: 1.8.0_121-b13
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: JVM Vendor: Oracle Corporation
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: CATALINA_BASE: C:\D\tomcat\apache-tomcat-8.0.43
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: CATALINA_HOME: C:\D\tomcat\apache-tomcat-8.0.43
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Command line argument: -Dcatalina.home=C:\D\tomcat\apache-tomcat-8.0.43
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Command line argument: -Dcatalina.base=C:\D\tomcat\apache-tomcat-8.0.43
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Command line argument: -Djava.endorsed.dirs=C:\D\tomcat\apache-tomcat-8.0.43/common/endorsed
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Command line argument: -Djava.io.tmpdir=C:\D\tomcat\apache-tomcat-8.0.43\temp
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Command line argument: -Djava.library.path=C:\Program Files\Java\jdk1.8.0_121\bin;C:\D\tomcat\apache-tomcat-8.0.43\bin
四月 22, 2017 10:18:28 下午 org.apache.catalina.startup.VersionLoggerListener log
資訊: Command line argument: -Dsun.io.useCanonCaches=false
四月 22, 2017 10:18:28 下午 org.apache.catalina.core.AprLifecycleListener lifecycleEvent
資訊: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jdk1.8.0_121\bin;C:\D\tomcat\apache-tomcat-8.0.43\bin
四月 22, 2017 10:18:29 下午 org.apache.coyote.AbstractProtocol init
資訊: Initializing ProtocolHandler [“http-nio-8080”]
四月 22, 2017 10:18:30 下午 org.apache.tomcat.util.net.NioSelectorPool getSharedSelector
資訊: Using a shared selector for servlet write/read
四月 22, 2017 10:18:30 下午 org.apache.coyote.AbstractProtocol init
資訊: Initializing ProtocolHandler [“ajp-nio-8009”]
四月 22, 2017 10:18:30 下午 org.apache.tomcat.util.net.NioSelectorPool getSharedSelector
資訊: Using a shared selector for servlet write/read
四月 22, 2017 10:18:30 下午 org.apache.catalina.startup.Catalina load
資訊: Initialization processed in 4964 ms
四月 22, 2017 10:18:30 下午 org.apache.catalina.core.StandardService startInternal
資訊: Starting service Catalina
四月 22, 2017 10:18:30 下午 org.apache.catalina.core.StandardEngine startInternal
資訊: Starting Servlet Engine: Apache Tomcat/8.0.43
四月 22, 2017 10:18:30 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\docs
四月 22, 2017 10:18:32 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deployment of web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\docs has finished in 1,979 ms
四月 22, 2017 10:18:32 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\examples
四月 22, 2017 10:18:35 下午 org.apache.catalina.core.ApplicationContext log
資訊: ContextListener: contextInitialized()
四月 22, 2017 10:18:35 下午 org.apache.catalina.core.ApplicationContext log
資訊: SessionListener: contextInitialized()
四月 22, 2017 10:18:35 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deployment of web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\examples has finished in 2,446 ms
四月 22, 2017 10:18:35 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\HelloMaven
四月 22, 2017 10:18:38 下午 org.apache.jasper.servlet.TldScanner scanJars
資訊: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
四月 22, 2017 10:18:38 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deployment of web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\HelloMaven has finished in 3,452 ms
四月 22, 2017 10:18:38 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\host-manager
四月 22, 2017 10:18:38 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deployment of web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\host-manager has finished in 148 ms
四月 22, 2017 10:18:38 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\manager
四月 22, 2017 10:18:39 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deployment of web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\manager has finished in 183 ms
四月 22, 2017 10:18:39 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deploying web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\ROOT
四月 22, 2017 10:18:39 下午 org.apache.catalina.startup.HostConfig deployDirectory
資訊: Deployment of web application directory C:\D\tomcat\apache-tomcat-8.0.43\webapps\ROOT has finished in 242 ms
四月 22, 2017 10:18:39 下午 org.apache.coyote.AbstractProtocol start
資訊: Starting ProtocolHandler [“http-nio-8080”]
四月 22, 2017 10:18:39 下午 org.apache.coyote.AbstractProtocol start
資訊: Starting ProtocolHandler [“ajp-nio-8009”]
四月 22, 2017 10:18:39 下午 org.apache.catalina.startup.Catalina start
資訊: Server startup in 8863 ms