首先说明一下，来来回回折腾两天，把遇到的问题进行总结。

一、下载

1、首先到github上下载，这个是分支地址，找到自己想要的版本：https://github.com/apache/incubator-dubbo/releases

我这里版本为incubator-dubbo-dubbo-2.5.4

二、安装Dubbo

解压文件之后先进到根目录先安装dubbo依赖，如果没有安装dubbo到时候安装dubbo-admin的时候就会报错，进到目录使用mvn package

等待出现success提示信息，则说明依赖安装成功，此时可以到你本地的mvn仓库上能看到dubbo-2.5.4-SNAPSHOT.jar。
目录是在你自己的本地mvn仓库上E:\Program Files\ApacheMaven3.5\MavenRepository\com\alibaba\dubbo\2.5.4-SNAPSHOT参考自己的目录。

三、安装Dubbo-admin

首先进到dubbo-admin模块目录下。
然后百度出一条命令开心的打包mvn package -Dmaven.test.skip=true。

此时非常开心，终于打包成功。
接下就把打包好的dubbo-admin-2.5.4-SNAPSHOT.war复制到tomcat的webapps目录下，当然名字太长我这里直接改成dubbo-admin.war。
此时可以启动tomcat。在tomcat的bin目录下找到startup.bat，双击运行启动，注意windows下是找到startup.bat，linux下是startup.sh。
启动完成后到浏览器输入localhost:8080/dubbo-admin。

然后百度找dubbo-admin启动404的相关文章，结果还是没有什么用。然后看到tomcat的启动日志文件，结果如下。

16-Oct-2018 10:02:44.155 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\dubbo-admin.war]
16-Oct-2018 10:02:54.888 信息 [localhost-startStop-1] org.apache.jasper.servlet.TldScanner.scanJars 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.
INFO: configuring "log4j" using file:/E:/InstallPackage/KFPackage/apache-tomcat-8.5.31/webapps/dubbo-admin/WEB-INF/log4j.xml
 - with property localAddress = 192.168.100.100
 - with property localHost = DESKTOP-1DFSV5L
 - with property loggingCharset = UTF-8
 - with property loggingLevel = INFO
 - with property loggingRoot = C:\Users\Kyrie\logs

 INFO context.ContextLoader - Root WebApplicationContext: initialization started
 INFO support.XmlWebApplicationContext - Refreshing Root WebApplicationContext: startup date [Tue Oct 16 10:02:55 CST 2018]; root of context hierarchy
 INFO xml.XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/applicationContext.xml]
ERROR context.ContextLoader - Context initialization failed
org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/applicationContext.xml]
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:344)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304)
        at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:181)
        at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:217)
        at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
        at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125)
        at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94)
        at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129)
        at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:614)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:515)
        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:4792)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5256)
        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.deployWAR(HostConfig.java:985)
        at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1857)
        at java.util.concurrent.Executors$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.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/applicationContext.xml]
        at org.springframework.web.context.support.ServletContextResource.getInputStream(ServletContextResource.java:141)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:330)
        ... 25 more
16-Oct-2018 10:02:55.573 严重 [localhost-startStop-1] org.apache.catalina.core.StandardContext.startInternal One or more listeners failed to start. Full details will be found in the appropriate container log file
16-Oct-2018 10:02:55.584 严重 [localhost-startStop-1] org.apache.catalina.core.StandardContext.startInternal Context [/dubbo-admin] startup failed due to previous errors
 INFO support.XmlWebApplicationContext - Closing Root WebApplicationContext: startup date [Tue Oct 16 10:02:55 CST 2018]; root of context hierarchy
 WARN support.XmlWebApplicationContext - Exception thrown from LifecycleProcessor on context close
java.lang.IllegalStateException: LifecycleProcessor not initialized - call 'refresh' before invoking lifecycle methods via the context: Root WebApplicationContext: startup date [Tue Oct 16 10:02:55 CST 2018]; root of context hierarchy
        at org.springframework.context.support.AbstractApplicationContext.getLifecycleProcessor(AbstractApplicationContext.java:427)
        at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:999)
        at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:958)
        at org.springframework.web.context.ContextLoader.closeWebApplicationContext(ContextLoader.java:583)
        at org.springframework.web.context.ContextLoaderListener.contextDestroyed(ContextLoaderListener.java:116)
        at org.apache.catalina.core.StandardContext.listenerStop(StandardContext.java:4839)
        at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5478)
        at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:226)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
        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.deployWAR(HostConfig.java:985)
        at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1857)
        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)
16-Oct-2018 10:02:55.656 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\dubbo-admin.war] has finished in [11,500] ms
16-Oct-2018 10:02:55.661 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\docs]
16-Oct-2018 10:02:55.745 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\docs] has finished in [83] ms
16-Oct-2018 10:02:55.752 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\examples]
16-Oct-2018 10:02:57.497 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\examples] has finished in [1,745] ms
16-Oct-2018 10:02:57.498 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\host-manager]
16-Oct-2018 10:02:57.579 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\host-manager] has finished in [81] ms
16-Oct-2018 10:02:57.580 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\manager]
16-Oct-2018 10:02:57.645 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\manager] has finished in [65] ms
16-Oct-2018 10:02:57.646 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\ROOT]
16-Oct-2018 10:02:57.692 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [E:\InstallPackage\KFPackage\apache-tomcat-8.5.31\webapps\ROOT] has finished in [47] ms
16-Oct-2018 10:02:57.701 信息 [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-nio-8080"]
16-Oct-2018 10:02:57.720 信息 [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["ajp-nio-8009"]
16-Oct-2018 10:02:57.729 信息 [main] org.apache.catalina.startup.Catalina.start Server startup in 13683 ms

结果发现dubbo-admin并没有启动。出现一个异常，这个异常明显说没有找到一个叫applicationContext.xml的文件，然后完全蒙蔽，别人打包的没问题我打包的居然报错。

ERROR context.ContextLoader - Context initialization failed
org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from ServletContext resource [/WEB-INF/applicationContext.xml]; nested exception is java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/applicationContext.xml]

各种百度查找。终于找到一个解决的办法。原来是spring版本太高要换成3.2.9.RELEASE，然后找到incubator-dubbo-dubbo-2.5.4下的pom.xml找到spring的版本改成3.2.9.RELEASE。
附上参考链接：https://my.oschina.net/iioschina/blog/1615086

修改完成之后保存从新打包一份，此时看到dubbo-admin目录下多了一个target文件，可以直接手动删除掉，或者执行命令mvn clean package -Dmaven.test.skip=true重新打包一份。
此时可以查看一下spring版本是否成功修改，进到lib目录下查看E:\setup\incubator-dubbo-dubbo-2.5.4\dubbo-admin\target\dubbo-admin-2.5.4-SNAPSHOT\WEB-INF\lib，根据自己目录。

然后又开心的把war包拿丢到webapps下启动tomcat。
看到tomcat启动信息停止一直不动如图

仔细看了一下信息原来是在需要连接zookeeper，然后先关掉tomcat，进到dubbo-admin下的WEB-INF目录下找到dubbo.properties修改zookeeper连接地址。由于我本地没有安装zookeeper，我连接的是阿里云上的zookeeper。

dubbo.registry.address=zookeeper://120.79.135.254:2181
dubbo.admin.root.password=root
dubbo.admin.guest.password=guest

注意：如果是连接阿里云上的zookeeper需要添加安全组规则。开放2181端口才可以，否则会报连接超时错误。这里就不截图了，我这里已经添加好安全级规则。添加安全组规则就不在说明，在本地是没有这个情况的。
此时在次启动tomcat，查看启动日志就没有发现错误，此时访问终于成功了。

默认用户名密码都是root，登录看到非常完美的dubbo-admin首页

四、总结

1、遇到报错需要仔细查看启动日志这些，找对关键字，看是哪个异常报错。
2、本地连接阿里云的服务需要添加对应端口的安全组规则。