11. 使用tomcat中碰到的一些问题

问题一：Tomcat的startup.bat启动后出现乱码

找到Tomcat文件下的conf目录，修改logging.properties文件中
java.util.logging.ConsoleHandler.encoding对应的值为GBK

重启Tomcat，你看到的启动页面是这样的话，说明乱码问题已经解决

问题二：一闪而退之端口占用

启动Tomcat出现一闪而退的现象，其实还是可以看到Tomcat终端输出的日志，
这时你需要迅速截图捕获异常，太南了。

最正确的方法是查看日志，找到Tomcat目录下的logs目录中catalina当天的日志，
我这里找到的是C:\develop\Tomcat\apache-tomcat-8.5.47\logs\catalina.2019-10-17.log，
在日志中可以看到类似这样的输出，Address already in use: bind说明是端口占用了

在Tomcat目录找到conf目录中的server.xml配置文件，在Connector标签中修改Tomcat启动端口

问题三：非端口问题的一闪而退

启动Tomcat直接一闪而退，在logs目录的日志里面找不到错误信息，
这个时候很大可能是因为Tomcat与JDK版本不对应导致的，有可能你的Tomcat是Tomcat9版，而你的JDK是1.7版本的，
Tomcat与JDK版本对应关系可以参考这篇文章Tomcat与JDK版本对应关系，Tomcat各版本特性

问题四：服务器的乱码和跨域问题

问题五: 在tomcat\webapps\下创建文件夹为什么tomcat重启就会丢失

1.修改/tomcat/conf/web.xml文件

        default
        org.apache.catalina.servlets.DefaultServlet
        
            debug
            0
        
        
            listings
            true
        
        1

2.修改/tomcat/conf/server.xml文件

3.总结

重新redeploy的时候，tomcat会同步你本地的文件 ，因为本地没有相应的文件夹导致文件丢失。
这只是在开发过程中会遇到的问题实际应用中tomcat会startup.bat/shutdown.bat。
我们这样做，其实就是给工程配置虚拟路径，这样tomcat在启动的时候直接找到工程了,
上传的图片就不会仅仅只在/tomcat/webapps/目录，而直接到了你的工程里,
不管你怎样重启项目，或者清理缓存，上传的文件依然存在!

问题六：Tomcat启动报java.io.EOFException错误

信息如下

2019-11-25 10:24:05 org.apache.catalina.startup.HostConfig deployDirectory
信息: Deploying web application directory ROOT
2019-11-25 10:24:05 org.apache.catalina.session.StandardManager doLoad
严重: IOException while loading persisted sessions: java.io.EOFException
java.io.EOFException
	at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2280)
	at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2749)
	at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:779)
	at java.io.ObjectInputStream.(ObjectInputStream.java:279)
	at org.apache.catalina.util.CustomObjectInputStream.(CustomObjectInputStream.java:58)
	at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:246)
	at org.apache.catalina.session.StandardManager.load(StandardManager.java:204)
	at org.apache.catalina.session.StandardManager.startInternal(StandardManager.java:465)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5025)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	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:570)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1010)
	at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:933)
	at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:468)
	at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1267)
	at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:308)
	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:328)
	at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:308)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1043)
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:738)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1035)
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:289)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:442)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:674)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:596)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:303)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:431)
2019-11-25 10:24:05 org.apache.catalina.session.StandardManager startInternal
严重: Exception loading sessions from persistent storage
java.io.EOFException
	at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2280)
	at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2749)
	at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:779)
	at java.io.ObjectInputStream.(ObjectInputStream.java:279)
	at org.apache.catalina.util.CustomObjectInputStream.(CustomObjectInputStream.java:58)
	at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:246)
	at org.apache.catalina.session.StandardManager.load(StandardManager.java:204)
	at org.apache.catalina.session.StandardManager.startInternal(StandardManager.java:465)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5025)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	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:570)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1010)
	at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:933)
	at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:468)
	at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1267)
	at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:308)
	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:328)
	at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:308)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1043)
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:738)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1035)
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:289)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:442)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:674)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:140)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:596)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:303)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:431)
2019-11-25 10:24:05 org.apache.catalina.startup.HostConfig deployDirectory

错误的原因是:EOFException表示输入过程中意外地到达文件尾或流尾的信号,导致从session中获取数据失败。
这是由于tomcat上次非正常关闭时有一些活动session被持久化（表现为一些临时文件），
在重启时，tomcat尝试去恢复这些session的持久化数据但又读取失败造成的。此异常不影响系统的使用。

可以看到,我正在使用的项目中多了一个sessions.ser文件,把此文件删除即可tomcat即可正常的使用.
如果你的项目中不知道是哪个项目引起的.就把Catalina目录下的所有文件删除,即可.

问题七：解决跨域问题

protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		resp.setHeader("Access-Control-Allow-Credentials", "true");
		resp.setHeader("Access-Control-Allow-Origin", req.getHeader("origin"));
		resp.setHeader("Access-Control-Allow-Methods", "*");
		resp.setHeader("Access-Control-Allow-Headers", "x-requested-with,content-type");
		resp.setContentType("application/json");
		resp.setCharacterEncoding("utf-8");
		super.doOptions(req, resp);
	}