先说下开发环境：
jdk1.7.0_45
最近开始使用maven构建项目（因为它实在太好用了），不过maven每次构建项目都要依赖中央仓库，这很不合理，所以使用了Nexus搭建了本地仓库，不过本地仓库搭建完成以后运行第一个命令mvn help:system就报了错，利用mvn -e help:system查看报错信息看了半天也没有头绪，下面就是这个报错信息：
[ERROR] Failed to execute goal
org.apache.maven.plugins:maven-help-plugin:2.2:system (default-cli) on
project standalone-pom: Execution default-cli of goal
org.apache.maven.plugins:maven-help-plugin:2.2:system failed: Plugin
org.apache.maven.plugins:maven-help-plugin:2.2 or one of its
dependencies could not be resolved: Failed to collect dependencies at
org.apache.maven.plugins:maven-help-plugin:jar:2.2 ->
org.apache.maven.plugin-tools:maven-plugin-tools-api:jar:2.4.3: Failed
to read artifact descriptor for
org.apache.maven.plugin-tools:maven-plugin-tools-api:jar:2.4.3:
Failure to find org.apache.maven:maven-parent:pom:8 in
http://127.0.0.1:8081/nexus/content/groups/public was cached in the
local repository, resolution will not be reattempted until the update
interval of roger-nexus has elapsed or updates are forced -> [Help
1]org.apache.maven.lifecycle.LifecycleExecutionException: Failed to
execute goal org.apache.maven.plugins:maven-help-plugin:2.2:system
(default-cli) on project standalone-pom: Execution default-cli of goal
org.apache.maven.plugins:maven-help-plugin:2.2:system failed: Plugin
org.apache.maven.plugins:maven-help-plugin:2.2 or one of its
dependencies could not be resolved: Failed to collect dependencies at
org.apache.maven.plugins:maven-help-plugin:jar:2.2 ->
org.apache.maven.plugin-tools:maven-plugin-tools-api:jar:2.4.3
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:224)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:317)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:152)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:555)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:214)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:158)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution
default-cli of goal
org.apache.maven.plugins:maven-help-plugin:2.2:system failed:
Pluginorg.apache.maven.plugins:maven-help-plugin:2.2 or one of its
dependencies couldnot be resolved: Failed to collect dependencies at
org.apache.maven.plugins:maven-help-plugin:jar:2.2 ->
org.apache.maven.plugin-tools:maven-plugin-tools-api:jar:2.4.3
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:87)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
... 19 more Caused by: org.apache.maven.plugin.PluginResolutionException: Plugin
org.apache.maven.plugins:maven-help-plugin:2.2 or one of its
dependencies could not be resolved: Failed to collect dependencies at
org.apache.maven.plugins:maven-help-plugin:jar:2.2 ->
org.apache.maven.plugin-tools:maven-plugin-tools-api:jar:2.4.3
at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolve(DefaultPluginDependenciesResolver.java:204)
at org.apache.maven.plugin.internal.DefaultMavenPluginManager.createPluginRealm(DefaultMavenPluginManager.java:357)
at org.apache.maven.plugin.internal.DefaultMavenPluginManager.setupPluginRealm(DefaultMavenPluginManager.java:325)
at org.apache.maven.plugin.DefaultBuildPluginManager.getPluginRealm(DefaultBuildPluginManager.java:180)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:83)
... 20 more Caused by: org.eclipse.aether.collection.DependencyCollectionException: Failed to
collect dependencies at
org.apache.maven.plugins:maven-help-plugin:jar:2.2
->org.apache.maven.plugin-tools:maven-plugin-tools-api:jar:2.4.3
at org.eclipse.aether.internal.impl.DefaultDependencyCollector.collectDependencies(DefaultDependencyCollector.java:292)
at org.eclipse.aether.internal.impl.DefaultRepositorySystem.collectDependencies(DefaultRepositorySystem.java:317)
at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolve(DefaultPluginDependenciesResolver.java:192)
... 24 more Caused by: org.eclipse.aether.resolution.ArtifactDescriptorException: Failed
toread artifact descriptor for
org.apache.maven.plugin-tools:maven-plugin-tools-ap i:jar:2.4.3
at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:370)
at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:217)
at org.eclipse.aether.internal.impl.DefaultDependencyCollector.process(DefaultDependencyCollector.java:461)
at org.eclipse.aether.internal.impl.DefaultDependencyCollector.collectDependencies(DefaultDependencyCollector.java:261)
... 26 more Caused by: org.apache.maven.model.resolution.UnresolvableModelException: Failure
to find org.apache.maven:maven-parent:pom:8 in
http://127.0.0.1:8081/nexus/content/groups/public was cached in the
local repository, resolution will not be reattempted until the update
interval of roger-nexus has elapsed or updates are for ced
at org.apache.maven.repository.internal.DefaultModelResolver.resolveModel(DefaultModelResolver.java:126)
at org.apache.maven.model.building.DefaultModelBuilder.readParentExternally(DefaultModelBuilder.java:817)
at org.apache.maven.model.building.DefaultModelBuilder.readParent(DefaultModelBuilder.java:669)
at org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:307)
at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:361)
... 29 more Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Failure to
find org.apache.maven:maven-parent:pom:8 in
http://127.0.0.1:8081/nexus/content/groups/public was cached in the
local repository, resolution will not be reattempted until the update
interval of roger-nexus has elapsed or updates are forced
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:459)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:262)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:239)
at org.apache.maven.repository.internal.DefaultModelResolver.resolveModel(DefaultModelResolver.java:122)
... 33 more Caused by: org.eclipse.aether.transfer.ArtifactNotFoundException: Failure to find
org.apache.maven:maven-parent:pom:8 in
http://127.0.0.1:8081/nexus/content/groups/public was cached in the
local repository, resolution will not be reattempted until the update
interval of roger-nexus has elapsed or updates are forced
at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.newException(DefaultUpdateCheckManager.java:232)
at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.checkArtifact(DefaultUpdateCheckManager.java:206)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.gatherDownloads(DefaultArtifactResolver.java:599)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:518)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:436)
... 36 more [ERROR] [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information
about the errors and possible solutions, please read the following
articles: [ERROR] [Help 1]
http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException
我搜索了一部分报错信息，参考了Stack Overflow上的一些问题，猜测有可能是有些网站被墙所以无法下载一些.pom文件，不过当我将我的setting.xml中关于nexus的配置注释掉以后mvn help:system完全可以正常运行，所以应该是setting.xml的设置有问题：
<?xml version="1.0" encoding="UTF-8"?>
<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>D:/DeveloperKit/maven_repos</localRepository>
<pluginGroups>
</pluginGroups>
<proxies>
</proxies>
<servers>
<server>
<id>roger-nexus</id>
<username>admin</username>
<password>admin123</password>
</server>
</servers>
<mirrors>
<mirror>
<id>roger-nexus</id>
<mirrorOf>*</mirrorOf>
<name>Mirror of roger</name>
<url>http://127.0.0.1:8081/nexus/content/groups/public</url>
</mirror>
</mirrors>
<profiles>
<profile>
<id>jdk-1.7</id>
<activation>
<jdk>1.7</jdk>
</activation>
<repositories>
<repository>
<id>jdk17</id>
<name>Repository for JDK 1.7 builds</name>
<url>http://127.0.0.1:8081/nexus/content/groups/public/</url>
<layout>default</layout>
<snapshotPolicy>always</snapshotPolicy>
</repository>
</repositories>
</profile>
</profiles>
<activeProfiles>
<activeProfile>jdk-1.7</activeProfile>
</activeProfiles>
</settings>
一样的清空，Failed to execute goal on project zheng-cms-common: Could not resolve dependencies for project com.zheng:zheng-cms-common:jar:1.0.0: Could not find artifact com.zheng:zheng-common:jar:1.0.0 in nexus (http://maven.i2p.com:8081/nexus/content/groups/public) -> [Help 1]