一、遇到的现象：
报错：IDEA Unable to import maven project: See logs for details
（ 直接现象： IDEA无法将下载的源码转成maven project，以致于项目缺少相应的包，最终导致项目无法运行！）
二、错误日志：
2020-01-07 13:40:08,540 [1074533] ERROR - #org.jetbrains.idea.maven - IntelliJ IDEA 2019.1.3 Build #IU-191.7479.19 2020-01-07 13:40:08,540 [1074533] ERROR - #org.jetbrains.idea.maven - JDK: 1.8.0_202-release; VM: OpenJDK 64-Bit Server VM; Vendor: JetBrains s.r.o 2020-01-07 13:40:08,540 [1074533] ERROR - #org.jetbrains.idea.maven - OS: Windows 10 2020-01-07 13:40:08,542 [1074535] ERROR - #org.jetbrains.idea.maven - Last Action: Maven.DownloadAllSources 2020-01-07 13:40:08,742 [1074735] INFO - .diagnostic.PerformanceWatcher - Pushing properties took 110ms; general responsiveness: ok; EDT responsiveness: ok 2020-01-07 13:40:08,819 [1074812] INFO - .diagnostic.PerformanceWatcher - Indexable file iteration took 67ms; general responsiveness: ok; EDT responsiveness: ok 2020-01-07 13:40:25,605 [1091598] WARN - ConfigurableExtensionPointUtil - ignore deprecated groupId: language for id: preferences.language.Kotlin.scripting 2020-01-07 13:40:26,080 [1092073] INFO - j.ide.plugins.RepositoryHelper - using cached plugin list (updated at 2020/1/7 12:25) 2020-01-07 13:41:11,038 [1137031] INFO - rationStore.ComponentStoreImpl - Saving Project 'C:UsersRaodiDesktopyinyueLandCirculationSystem' LandCirculationSystemlibraryTable took 17 ms 2020-01-07 13:41:11,070 [1137063] INFO - mponents.impl.stores.StoreUtil - saveProjectsAndApp took 93 ms 2020-01-07 13:41:12,160 [1138153] INFO - pl.ProjectRootManagerComponent - project roots have changed 2020-01-07 13:41:12,259 [1138252] INFO - indexing.UnindexedFilesUpdater - Unindexed files update canceled 2020-01-07 13:41:12,261 [1138254] INFO - pl.ProjectRootManagerComponent - project roots have changed 2020-01-07 13:41:12,313 [1138306] ERROR - #org.jetbrains.idea.maven - Cannot reconnect. java.lang.RuntimeException: Cannot reconnect. at org.jetbrains.idea.maven.server.RemoteObjectWrapper.perform(RemoteObjectWrapper.java:82) at org.jetbrains.idea.maven.server.MavenServerManager.applyProfiles(MavenServerManager.java:404) at org.jetbrains.idea.maven.project.MavenProjectReader.applyProfiles(MavenProjectReader.java:399) at org.jetbrains.idea.maven.project.MavenProjectReader.doReadProjectModel(MavenProjectReader.java:108) at org.jetbrains.idea.maven.project.MavenProjectReader.readProject(MavenProjectReader.java:67) at org.jetbrains.idea.maven.project.MavenProject.read(MavenProject.java:665) at org.jetbrains.idea.maven.project.MavenProjectsTree.doUpdate(MavenProjectsTree.java:555) at org.jetbrains.idea.maven.project.MavenProjectsTree.doAdd(MavenProjectsTree.java:500) at org.jetbrains.idea.maven.project.MavenProjectsTree.update(MavenProjectsTree.java:461) at org.jetbrains.idea.maven.project.MavenProjectsTree.update(MavenProjectsTree.java:443) at org.jetbrains.idea.maven.project.MavenProjectsProcessorReadingTask.perform(MavenProjectsProcessorReadingTask.java:65) at org.jetbrains.idea.maven.project.MavenProjectsProcessor.doProcessPendingTasks(MavenProjectsProcessor.java:135) at org.jetbrains.idea.maven.project.MavenProjectsProcessor.access$000(MavenProjectsProcessor.java:32) at org.jetbrains.idea.maven.project.MavenProjectsProcessor$2.run(MavenProjectsProcessor.java:109) at org.jetbrains.idea.maven.utils.MavenUtil.lambda$runInBackground$5(MavenUtil.java:458) at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:311) at java.util.concurrent.Executors$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$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748) Caused by: java.rmi.RemoteException: Cannot start maven service; nested exception is: com.intellij.execution.ExecutionException at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:169) at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:74) at org.jetbrains.idea.maven.server.RemoteObjectWrapper.getOrCreateWrappee(RemoteObjectWrapper.java:41) at org.jetbrains.idea.maven.server.MavenServerManager.lambda$applyProfiles$3(MavenServerManager.java:404) at org.jetbrains.idea.maven.server.RemoteObjectWrapper.perform(RemoteObjectWrapper.java:76) ... 20 more Caused by: com.intellij.execution.ExecutionException at com.intellij.execution.rmi.RemoteProcessSupport.acquire(RemoteProcessSupport.java:144) at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:166) ... 24 more Caused by: java.lang.AssertionError at org.jetbrains.idea.maven.server.MavenServerManager$MavenServerCMDState.createJavaParameters(MavenServerManager.java:731) at org.jetbrains.idea.maven.server.MavenServerManager$MavenServerCMDState.startProcess(MavenServerManager.java:793) at org.jetbrains.idea.maven.server.MavenServerManager$MavenServerCMDState.execute(MavenServerManager.java:786) at com.intellij.execution.rmi.RemoteProcessSupport.startProcess(RemoteProcessSupport.java:197) at com.intellij.execution.rmi.RemoteProcessSupport.acquire(RemoteProcessSupport.java:124) ... 25 more
三、解决方法
1、重新下载maven （此步建议不做，从第2步骤开始）
在idea中，依次点击“File” -> "Setting .." -> "Plugins" ,在Marketplace中搜索插件，“Maven Integration”和“Maven Integration Extension” ，并安装
2、配置阿里云镜像库和本地库
找到内嵌intellij idea的maven包，首先在系统中找到idea的本地程序的安装目录，建议在idea的快捷方式上一路选择 “打开文件位置”
再返回上一级目录，继续进入“pluginsmavenlib”路径，如下图，这时会看到intellij idea内嵌的maven
修改“maven3conf”目录下的settings.xml文件，修改的内容如下：
<localRepository>C:UsersRaodiAppDataLocalJetBrainsToolboxappsIDEA-Uch-0191.7479.19pluginsmavenlibmaven3lib</localRepository>
<mirror> <id>alimaven</id> <name>aliyun maven</name> <url>http://maven.aliyun.com/nexus/content/groups/public/</url> <mirrorOf>central</mirrorOf> </mirror>
记得<localRepository></localRepository>的地址内容，建议配置成下图的文件夹，因为有许多的地方会引用该文件夹
完整的文件内容：
<?xml version="1.0" encoding="UTF-8"?> <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <!-- | This is the configuration file for Maven. It can be specified at two levels: | | 1. User Level. This settings.xml file provides configuration for a single user, | and is normally provided in ${user.home}/.m2/settings.xml. | | NOTE: This location can be overridden with the CLI option: | | -s /path/to/user/settings.xml | | 2. Global Level. This settings.xml file provides configuration for all Maven | users on a machine (assuming they're all using the same Maven | installation). It's normally provided in | ${maven.conf}/settings.xml. | | NOTE: This location can be overridden with the CLI option: | | -gs /path/to/global/settings.xml | | The sections in this sample file are intended to give you a running start at | getting the most out of your Maven installation. Where appropriate, the default | values (values used when the setting is not specified) are provided. | |--> <settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd"> <!-- localRepository | The path to the local repository maven will use to store artifacts. | | Default: ${user.home}/.m2/repository <localRepository>/path/to/local/repo</localRepository> --> <localRepository>C:UsersRaodiAppDataLocalJetBrainsToolboxappsIDEA-Uch-0191.7479.19pluginsmavenlibmaven3lib</localRepository> <!-- interactiveMode | This will determine whether maven prompts you when it needs input. If set to false, | maven will use a sensible default value, perhaps based on some other setting, for | the parameter in question. | | Default: true <interactiveMode>true</interactiveMode> --> <!-- offline | Determines whether maven should attempt to connect to the network when executing a build. | This will have an effect on artifact downloads, artifact deployment, and others. | | Default: false <offline>false</offline> --> <!-- pluginGroups | This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e. | when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers | "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list. |--> <pluginGroups> <!-- pluginGroup | Specifies a further group identifier to use for plugin lookup. <pluginGroup>com.your.plugins</pluginGroup> --> </pluginGroups> <!-- proxies | This is a list of proxies which can be used on this machine to connect to the network. | Unless otherwise specified (by system property or command-line switch), the first proxy | specification in this list marked as active will be used. |--> <proxies> <!-- proxy | Specification for one proxy, to be used in connecting to the network. | <proxy> <id>optional</id> <active>true</active> <protocol>http</protocol> <username>proxyuser</username> <password>proxypass</password> <host>proxy.host.net</host> <port>80</port> <nonProxyHosts>local.net|some.host.com</nonProxyHosts> </proxy> --> </proxies> <!-- servers | This is a list of authentication profiles, keyed by the server-id used within the system. | Authentication profiles can be used whenever maven must make a connection to a remote server. |--> <servers> <!-- server | Specifies the authentication information to use when connecting to a particular server, identified by | a unique name within the system (referred to by the 'id' attribute below). | | NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are | used together. | <server> <id>deploymentRepo</id> <username>repouser</username> <password>repopwd</password> </server> --> <!-- Another sample, using keys to authenticate. <server> <id>siteServer</id> <privateKey>/path/to/private/key</privateKey> <passphrase>optional; leave empty if not used.</passphrase> </server> --> </servers> <!-- mirrors | This is a list of mirrors to be used in downloading artifacts from remote repositories. | | It works like this: a POM may declare a repository to use in resolving certain artifacts. | However, this repository may have problems with heavy traffic at times, so people have mirrored | it to several places. | | That repository definition will have a unique id, so we can create a mirror reference for that | repository, to be used as an alternate download site. The mirror site will be the preferred | server for that repository. |--> <mirrors> <!-- mirror | Specifies a repository mirror site to use instead of a given repository. The repository that | this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used | for inheritance and direct lookup purposes, and must be unique across the set of mirrors. | <mirror> <id>mirrorId</id> <mirrorOf>repositoryId</mirrorOf> <name>Human Readable Name for this Mirror.</name> <url>http://my.repository.com/repo/path</url> </mirror> --> <!--<mirror> <id>aliyun</id> <name>aliyun Maven</name> <mirrorOf>*</mirrorOf> <url>http://maven.aliyun.com/nexus/content/groups/public/</url> </mirror> --> <mirror> <id>alimaven</id> <name>aliyun maven</name> <url>http://maven.aliyun.com/nexus/content/groups/public/</url> <mirrorOf>central</mirrorOf> </mirror> </mirrors> <!-- profiles | This is a list of profiles which can be activated in a variety of ways, and which can modify | the build process. Profiles provided in the settings.xml are intended to provide local machine- | specific paths and repository locations which allow the build to work in the local environment. | | For example, if you have an integration testing plugin - like cactus - that needs to know where | your Tomcat instance is installed, you can provide a variable here such that the variable is | dereferenced during the build process to configure the cactus plugin. | | As noted above, profiles can be activated in a variety of ways. One way - the activeProfiles | section of this document (settings.xml) - will be discussed later. Another way essentially | relies on the detection of a system property, either matching a particular value for the property, | or merely testing its existence. Profiles can also be activated by JDK version prefix, where a | value of '1.4' might activate a profile when the build is executed on a JDK version of '1.4.2_07'. | Finally, the list of active profiles can be specified directly from the command line. | | NOTE: For profiles defined in the settings.xml, you are restricted to specifying only artifact | repositories, plugin repositories, and free-form properties to be used as configuration | variables for plugins in the POM. | |--> <profiles> <!-- profile | Specifies a set of introductions to the build process, to be activated using one or more of the | mechanisms described above. For inheritance purposes, and to activate profiles via <activatedProfiles/> | or the command line, profiles have to have an ID that is unique. | | An encouraged best practice for profile identification is to use a consistent naming convention | for profiles, such as 'env-dev', 'env-test', 'env-production', 'user-jdcasey', 'user-brett', etc. | This will make it more intuitive to understand what the set of introduced profiles is attempting | to accomplish, particularly when you only have a list of profile id's for debug. | | This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo. <profile> <id>jdk-1.4</id> <activation> <jdk>1.4</jdk> </activation> <repositories> <repository> <id>jdk14</id> <name>Repository for JDK 1.4 builds</name> <url>http://www.myhost.com/maven/jdk14</url> <layout>default</layout> <snapshotPolicy>always</snapshotPolicy> </repository> </repositories> </profile> --> <!-- | Here is another profile, activated by the system property 'target-env' with a value of 'dev', | which provides a specific path to the Tomcat instance. To use this, your plugin configuration | might hypothetically look like: | | ... | <plugin> | <groupId>org.myco.myplugins</groupId> | <artifactId>myplugin</artifactId> | | <configuration> | <tomcatLocation>${tomcatPath}</tomcatLocation> | </configuration> | </plugin> | ... | | NOTE: If you just wanted to inject this configuration whenever someone set 'target-env' to | anything, you could just leave off the <value/> inside the activation-property. | <profile> <id>env-dev</id> <activation> <property> <name>target-env</name> <value>dev</value> </property> </activation> <properties> <tomcatPath>/path/to/tomcat/instance</tomcatPath> </properties> </profile> --> </profiles> <!-- activeProfiles | List of profiles that are active for all builds. | <activeProfiles> <activeProfile>alwaysActiveProfile</activeProfile> <activeProfile>anotherAlwaysActiveProfile</activeProfile> </activeProfiles> --> </settings>
3、设置为intellij idea项目默认maven
依次点击“File” -> "Other Settings" -> "Settings for New Projects.." ,在打开的面板中搜索“maven”
选择“maven”后 ，将“Maven home directory:” 的内容设置为intellij idea安装目录中深藏的maven 的家目录即可，最后重新启动intellij idea即可，如下图：
