前言：
我先简单说下这个项目的架构，前端是vue框架，后台是普通的ssm(SpringSpringMVCMybatis)框架,项目是用Tomcat启动的，nginx用来间接解决前端和后端跨域的问题，然后用redis做缓存来减少直接访问数据库的压力。标题中出现的问题，是我在Linux环境下部署项目时出现的，我分别安装好了redis-3.2.11、nginx-1.14.0、apache-tomcat-8.5.30，（这些软件和项目安装在同一个服务器下）然后在用tomcat启动项目时报错啦，这篇文章讲解下解决这个问题的方法。
正文：
一、异常场景复现
1.最开始/etc下的hosts文件的内容，只有这两行
2.redis可以正常启动，检验办法如下
搜索redis关键字
使用redis-cli客户端检测连接是否正常
3.我用tomcat的指令启动项目，
./startup.sh4.然后就出现了下面的异常信息
java.net.UnknownHostException: ctc_dxtrh_app04: ctc_dxtrh_app04: Name or service not known
at java.net.InetAddress.getLocalHost(InetAddress.java:1506)
at redis.clients.jedis.HostAndPort.getLocalHostQuietly(HostAndPort.java:105)
at redis.clients.jedis.HostAndPort.<clinit>(HostAndPort.java:12)
at redis.clients.jedis.JedisFactory.<init>(JedisFactory.java:37)
at redis.clients.jedis.JedisPool.<init>(JedisPool.java:185)
at redis.clients.jedis.JedisPool.<init>(JedisPool.java:169)
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.createRedisPool(JedisConnectionFactory.java:275)
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.createPool(JedisConnectionFactory.java:250)
at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.afterPropertiesSet(JedisConnectionFactory.java:237)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1688)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1626)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1533)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1280)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1268)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1268)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4776)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5240)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:754)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:730)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:629)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1838)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.UnknownHostException: ctc_dxtrh_app04: Name or service not known
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:929)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1324)
at java.net.InetAddress.getLocalHost(InetAddress.java:1501)
... 71 more二、解决方案
1.我先翻译下这个异常的意思
java.net.UnknownHostException: ctc_dxtrh_app04: ctc_dxtrh_app04: Name or service not
大概的意思就是， ctc_dxtrh_app04: ctc_dxtrh_app04这个东西的名字或服务找不到
这里，我告诉你这个ctc_dxtrh_app04就是你Linux的主机名
2.主机名可以通过>hostname指令查看
3.那沿着这条线我就知道需要去修改主机名的映射就可以啦（主机名找不到为什需要修改host文件，可以查看下host文件的作用：https://www.jb51.net/article/133910.htm）
4.编辑hosts文件，修改成如下图
vi /etc/hosts
修改规律就是：
127.0.0.1 主机名(新增加的部分) localhost...........................
: : 1 localhost.................
127.0.0.1 主机名（新增加的部分）
5.修改完成后，再重新启动tomcat，就可以正常启动啦
总结：
开发中会遇到各种各样的问题，这时候冷静下来一步一步的去分析，然后猜测问题出现的原因，再去操作验证，保持一个不急躁的心态很重要。我是阿达，一名喜欢分享知识的程序员，时不时的也会荒腔走板的聊一聊电影、电视剧、音乐、漫画，这里已经有42位小伙伴在等你们啦，感兴趣的就赶紧来点击关注我把，哪里有不明白或有不同观点的地方欢迎留言。