如何使 Netty 示例有效答案

【问题标题】：How to make the Netty example works如何使 Netty 示例有效
【发布时间】：2016-02-04 06:53:29
【问题描述】：

我试图下载Netty Source Code 并运行包含的示例。

我安装的jdk版本是1.8.0_65。

我尝试使用 maven(mvn eclipse:eclipse) 将示例（在示例文件夹 ...\netty-4.1\example 中）转换为 eclipse 项目。

但是得到下面所说的构建错误。

[INFO]
[INFO] >>> maven-eclipse-plugin:2.10:eclipse (default-cli) > generate-resources @ netty-example >>>
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.558 s
[INFO] Finished at: 2016-02-04T13:40:13+08:00
[INFO] Final Memory: 11M/28M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal on project netty-example: Could not resolve dependencies for project io.netty:netty-example:jar:4.1.0.CR2-SNAPSHOT: Failure to fi
nd io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 in https://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be r
eattempted until the update interval of central has elapsed or updates are forced -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal on project netty-example: Could not resolve dependencies for project io.netty:net
ty-example:jar:4.1.0.CR2-SNAPSHOT: Failure to find io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 in https://repo.maven.apache.org/maven2 was cached i
n the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced
        at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.getDependencies(LifecycleDependencyResolver.java:221)
        at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.resolveProjectDependencies(LifecycleDependencyResolver.java:127)
        at org.apache.maven.lifecycle.internal.MojoExecutor.ensureDependenciesAreResolved(MojoExecutor.java:245)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:199)
        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.MojoExecutor.executeForkedExecutions(MojoExecutor.java:352)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:197)
        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:116)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
        at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        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.project.DependencyResolutionException: Could not resolve dependencies for project io.netty:netty-example:jar:4.1.0.CR2-SNAPSHOT: Fai
lure to find io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 in https://repo.maven.apache.org/maven2 was cached in the local repository, resolution wil
l not be reattempted until the update interval of central has elapsed or updates are forced
        at org.apache.maven.project.DefaultProjectDependenciesResolver.resolve(DefaultProjectDependenciesResolver.java:211)
        at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.getDependencies(LifecycleDependencyResolver.java:195)
        ... 27 more
Caused by: org.eclipse.aether.resolution.DependencyResolutionException: Failure to find io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 in https://repo
.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are
forced
        at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveDependencies(DefaultRepositorySystem.java:384)
        at org.apache.maven.project.DefaultProjectDependenciesResolver.resolve(DefaultProjectDependenciesResolver.java:205)
        ... 28 more
Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Failure to find io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 in https://repo.m
aven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are fo
rced
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:444)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:246)
        at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveDependencies(DefaultRepositorySystem.java:367)
        ... 29 more
Caused by: org.eclipse.aether.transfer.ArtifactNotFoundException: Failure to find io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 in https://repo.maven
.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced

        at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.newException(DefaultUpdateCheckManager.java:231)
        at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.checkArtifact(DefaultUpdateCheckManager.java:206)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.gatherDownloads(DefaultArtifactResolver.java:585)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:503)
        at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:421)
        ... 31 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/DependencyResolutionException

我按照消息中提到的线索进行操作。我找到了链接到http://netty.io/wiki/forked-tomcat-native.html#wiki-h3-6 的this solution。

我认为这可能不是我的目的。（我只想运行示例）。

所以我想知道要下载任何 Netty 开发库以开始 Netty 应用程序开发。或者任何 Pom.xml 共享链接都可以很容易地包含在示例项目中？谢谢。

【问题讨论】：

您尝试过Force maven update 中的说明吗？它有助于解决was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced 问题。
是的。我已经尝试过mvn clean install -U。错误仍然存在。
我对它试图下载“io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11”的事实感到困惑。你的设置有什么奇怪的东西，比如 32 位 maven 或类似的东西吗？？
我认为不是，因为 maven 确实适用于我计算机中的其他项目。所以maven设置没问题。对吗？
哦。找到了。 mvn -version 返回OS name: "windows 7", version: "6.1", arch: "x86", family: "dos"。这是否意味着我的计算机中的 32 位 maven？谢谢

标签： java eclipse maven netty

【解决方案1】：

这个答案是根据 Netty 项目上的bug report 做出的。

要构建 Netty 项目，您应该使用 64 位操作系统和 64 位 JVM。这是因为 Netty 项目使用的依赖项中有 1 个只支持 64 位。

根据mvn -version 的输出，您在32 位JVM 上运行。您应该可以从official java website 下载 64 位 JVM。

升级到 64 位 JVM 还具有以下优势：

您可以运行超过 2 GB 内存的程序
使用 long 和 double 的计算会更快，因为 java 可以使用本机处理器

有关差异，请参阅：Benefits of 64bit java platform

你不需要自己编译示例，你也可以在 maven Central 上找到它们，按版本排序：http://central.maven.org/maven2/io/netty/netty-example/

【讨论】：

【解决方案2】：

看日志，好像没找到tcnative jar

找不到 io.netty:netty-tcnative:jar:windows-x86_32:1.1.33.Fork11 在 https://repo.maven.apache.org/maven2 被缓存在本地存储库，

您可以尝试使用 maven 从命令行下载这个 tcnative jar，如下所示：

mvn org.apache.maven.plugins:maven-dependency-plugin:get -DrepoUrl=http://central.maven.org/maven2/  -DgroupId=io.netty -DartifactId=netty-tcnative -Dversion=1.1.33.Fork11

【讨论】：

它不起作用。我这边可以访问网址http://central.maven.org/maven2/。顺便说一句，为什么我在您提到的网址中找不到“netty-tcnative”或tcnative？谢谢。
@Joe.wang 我的错。我发布了-Dversion: 而不是-Dversion=。你现在可以试试。我已经更新了命令。您还可以在http://central.maven.org/maven2/io/netty/netty-tcnative/ 找到 tcnative poms 和 jars
真的有效！我也想知道提供的错误网址repo.maven.apache.org/maven2 在哪里？在我的 Maven 设置或 Netty 源项目中？谢谢。
我不能说这是错误的 URL。但它是在你的 maven 安装的超级 POM 中配置的。它可以在 maven/lib 文件夹下的maven-model-builder-3.3.9.jar 中的org/apache/maven/model/pom-4.0.0.xml 文件中找到
:) 知道了。所以我想我最好在我的 pom.xml 中添加更多的存储库 url。对吗？