maven基础教程

maven指南

@(OTHERS)[maven]

1、maven下载出错

有时候maven编译或者打包时下载包的阶段出错，一般都是网络问题，相信自己，你没写错。如：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.18.1:test (default-test) on project myusml: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.18.1:test failed: Plugin org.apache.maven.plugins:maven-surefire-plugin:2.18.1 or one of its dependencies could not be resolved: Failed to collect dependencies at org.apache.maven.plugins:maven-surefire-plugin:jar:2.18.1 -> org.apache.maven.surefire:maven-surefire-common:jar:2.18.1: Failed to read artifact descriptor for org.apache.maven.surefire:maven-surefire-common:jar:2.18.1: Could not transfer artifact org.apache.maven.surefire:maven-surefire-common:pom:2.18.1 from/to central (https://repo.maven.apache.org/maven2): Remote host closed connection during handshake: SSL peer shut down incorrectly -> [Help 1]

国内访问某些外国网站的网络很不稳定，因此需要添加国内的中央库：

1、修改$M2_HOME/conf/setting.xml中添加国内的源
（1）配置 mirror

...
        
            osc
            central
            http://maven.oschina.net/content/groups/public/
        
        
            osc_thirdparty
            thirdparty
            http://maven.oschina.net/content/repositories/thirdparty/
        
...

（2）配置 profile

...
        
            osc
            
                true
            
            
                
                    osc
                    http://maven.oschina.net/content/groups/public/
                
                
                    osc_thirdparty
                    http://maven.oschina.net/content/repositories/thirdparty/
                
            
            
                
                    osc
                    http://maven.oschina.net/content/groups/public/
                
            
        
...

详见http://maven.oschina.net/help.html

2、出现以下错误：
Description Resource Path Location Type Could not calculate build plan: Failure to transfer org.apache.maven.plugins:maven-compiler-plugin:pom:2.0.2

执行：
find ~/.m2 -name “*.lastUpdated” -exec grep -q “Could not transfer” {} \; -print -exec rm {} \;
原因是之前有一些下载失败了。
详见http://stackoverflow.com/questions/5074063/maven-error-failure-to-transfer

3、配置eclipse使用本地安装的maven，而不是自带的版本。同时在User setting里面，也要指定setting.xml是使用哪个配置文件，从而指定国内的库。
否则国内有时候连不上maven中央库，导致出现以下异常：

Description Resource    Path    Location    Type
Failed to read artifact descriptor for org.apache.storm:storm-core:jar:0.10.0

org.eclipse.aether.resolution.ArtifactDescriptorException: Failed to read artifact descriptor for org.apache.storm:storm-core:jar:0.10.0
    at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:302)
    at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:218)
    at org.eclipse.aether.internal.impl.DefaultDependencyCollector.resolveCachedArtifactDescriptor(DefaultDependencyCollector.java:535)
    at org.eclipse.aether.internal.impl.DefaultDependencyCollector.getArtifactDescriptorResult(DefaultDependencyCollector.java:519)
    at org.eclipse.aether.internal.impl.DefaultDependencyCollector.processDependency(DefaultDependencyCollector.java:409)
    at org.eclipse.aether.internal.impl.DefaultDependencyCollector.processDependency(DefaultDependencyCollector.java:363)
    at org.eclipse.aether.internal.impl.DefaultDependencyCollector.process(DefaultDependencyCollector.java:351)
    at org.eclipse.aether.internal.impl.DefaultDependencyCollector.collectDependencies(DefaultDependencyCollector.java:254)
    at org.eclipse.aether.internal.impl.DefaultRepositorySystem.collectDependencies(DefaultRepositorySystem.java:316)
    at org.apache.maven.project.DefaultProjectDependenciesResolver.resolve(DefaultProjectDependenciesResolver.java:172)
    at org.apache.maven.project.DefaultProjectBuilder.resolveDependencies(DefaultProjectBuilder.java:215)
    at org.apache.maven.project.DefaultProjectBuilder.build(DefaultProjectBuilder.java:188)
    at org.apache.maven.project.DefaultProjectBuilder.build(DefaultProjectBuilder.java:119)
    at org.eclipse.m2e.core.internal.embedder.MavenImpl.readMavenProject(MavenImpl.java:636)
    at org.eclipse.m2e.core.internal.project.registry.DefaultMavenDependencyResolver.resolveProjectDependencies(DefaultMavenDependencyResolver.java:63)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.refreshPhase2(ProjectRegistryManager.java:529)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager$3.call(ProjectRegistryManager.java:491)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager$3.call(ProjectRegistryManager.java:1)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:151)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.refresh(ProjectRegistryManager.java:495)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.refresh(ProjectRegistryManager.java:350)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.refresh(ProjectRegistryManager.java:297)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager.updateProjectConfiguration0(ProjectConfigurationManager.java:398)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager$2.call(ProjectConfigurationManager.java:345)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager$2.call(ProjectConfigurationManager.java:1)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:151)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:99)
    at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:1351)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager.updateProjectConfiguration(ProjectConfigurationManager.java:342)
    at org.eclipse.m2e.core.ui.internal.UpdateMavenProjectJob.runInWorkspace(UpdateMavenProjectJob.java:77)
    at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)
Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Failure to transfer org.apache.storm:storm-core:pom:0.10.0 from 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. Original error: Could not transfer artifact org.apache.storm:storm-core:pom:0.10.0 from/to central (https://repo.maven.apache.org/maven2): Remote host closed connection during handshake
    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.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:223)
    at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:287)
    ... 33 more
Caused by: org.eclipse.aether.transfer.ArtifactTransferException: Failure to transfer org.apache.storm:storm-core:pom:0.10.0 from 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. Original error: Could not transfer artifact org.apache.storm:storm-core:pom:0.10.0 from/to central (https://repo.maven.apache.org/maven2): Remote host closed connection during handshake
    at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.newException(DefaultUpdateCheckManager.java:238)
    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)
    ... 36 more
    pom.xml /stormfilter    line 1  Maven Dependency Problem

如果还不行，先到命令行执行mvn clean package，看原因是什么，很有可能是连接中央库失败。

2、打包超级包：shade与provided

默认情况下，maven package只会将用户的代码打包，它会认为运行机器的classpath中存在它所需要的依赖包。但有时候需要将项目的所有依赖包都打包到发布的jar包中，此时可以通过以下的plugin实现：

    
        
            org.apache.maven.plugins
            maven-shade-plugin
            2.3
            
                
                    package
                    
                        shade
                    
                
            
            
                
                    
                        *:*
                        
                            META-INF/*.SF
                            META-INF/*.DSA
                            META-INF/*.RSA
                        
                    
                
            
        
    

如果有一部分依赖包不想打包进jar包中，可以指定其为provided。比如运行一个spark程序时，classpath中必然会加载spark的包，此时就可以将spark指定为provided。

    
        org.apache.spark
        spark-core_2.10
        1.5.1
        provided
    

使用这个plugin有可能出现以下错误：

2016-08-11 10:08:54,902 ERROR org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost: Failed to load coprocessor com.lujinhong.hbase.solr.indexer.SolrIndexerObserver
java.lang.SecurityException: Invalid signature file digest for Manifest main attributes
    at sun.security.util.SignatureFileVerifier.processImpl(SignatureFileVerifier.java:286)
    at sun.security.util.SignatureFileVerifier.process(SignatureFileVerifier.java:239)
    at java.util.jar.JarVerifier.processEntry(JarVerifier.java:317)
    at java.util.jar.JarVerifier.update(JarVerifier.java:228)
    at java.util.jar.JarFile.initializeVerifier(JarFile.java:348)
    at java.util.jar.JarFile.getInputStream(JarFile.java:415)
    at sun.misc.URLClassPath$JarLoader$2.getInputStream(URLClassPath.java:775)
    at sun.misc.Resource.cachedInputStream(Resource.java:77)
    at sun.misc.Resource.getByteBuffer(Resource.java:160)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:436)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at org.apache.hadoop.hbase.util.CoprocessorClassLoader.loadClass(CoprocessorClassLoader.java:292)
    at org.apache.hadoop.hbase.coprocessor.CoprocessorHost.load(CoprocessorHost.java:183)
    at org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost.loadTableCoprocessors(RegionCoprocessorHost.java:326)
    at org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost.(RegionCoprocessorHost.java:225)
    at org.apache.hadoop.hbase.regionserver.HRegion.(HRegion.java:773)
    at org.apache.hadoop.hbase.regionserver.HRegion.(HRegion.java:681)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    at org.apache.hadoop.hbase.regionserver.HRegion.newHRegion(HRegion.java:5677)
    at org.apache.hadoop.hbase.regionserver.HRegion.openHRegion(HRegion.java:5987)
    at org.apache.hadoop.hbase.regionserver.HRegion.openHRegion(HRegion.java:5959)
    at org.apache.hadoop.hbase.regionserver.HRegion.openHRegion(HRegion.java:5915)
    at org.apache.hadoop.hbase.regionserver.HRegion.openHRegion(HRegion.java:5866)
    at org.apache.hadoop.hbase.regionserver.handler.OpenRegionHandler.openRegion(OpenRegionHandler.java:356)
    at org.apache.hadoop.hbase.regionserver.handler.OpenRegionHandler.process(OpenRegionHandler.java:126)
    at org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:128)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

解决方法见：
http://stackoverflow.com/questions/999489/invalid-signature-file-when-attempting-to-run-a-jar

即在plugin中添加以下内容【上面例子中已经包括了】：

    
        
            *:*
            
                META-INF/*.SF
                META-INF/*.DSA
                META-INF/*.RSA
            
        
    
    

3、依赖冲突：NoSuchMethodError, ClassNotFoundException

如果在运行中出现NoSuchMethodError或者ClassNotFoundException的异常，而你又确定classpath中存在这个包，那是因为你的classpath中存在2个不同版本的jar包了，比如常见的log4j，你在classpath中添加了log4j.jar，而spark的lib目录中也有log4j.jar，而且这2个jar包版本不一致的话，就会出现这种问题。

解决办法有2种：
（1）修改程序，让你的代码使用spark（比如）提供的jar包的版本。
（2）使用称为shading的方式修改你的应用。使用上面提到的maven-shade-plugin插件进行高级配置来支持这种打包方式。shading可以让你以另一种命名空间保留冲突的包，并自动重写应用的代码使得它们使用重命名后的版本。这种技术有些简单粗暴，不过对于解决运行时依赖冲突的问题非常有效。

另一个例子，storm使用了log4j2.x，而hbase使用了1.x，因此在storm项目中导入hbase需要将其exclude掉：

    
        org.apache.hbase
        hbase-client
        1.0.0
        
            
                org.slf4j
                slf4j-api
            
            
                org.slf4j
                slf4j-log4j12
            
            
                log4j
                log4j
            
        
    

只要log4j有类似NoClassDefindFound之类的冲突都这样解决。

4、添加CDH的依赖

在pom.xml中增加以下内容：

        
            cloudera
            https://repository.cloudera.com/artifactory/cloudera-repos/
        
    

然后指定CDH的版本：

    
        org.apache.hbase
        hbase-client
        1.0.0-cdh5.4.5
    

版本号可以从https://repository.cloudera.com/artifactory/cloudera-repos/查到。

5、忽略测试

-DskipTests，不执行测试用例，但编译测试用例类生成相应的class文件至target/test-classes下。

-Dmaven.test.skip=true，不执行测试用例，也不编译测试用例类。

6、调整jdk版本

在标签中增加以下内容

  
      1.8
      1.8
      1.8
  
  

如果不指定这些参数，则会使用$JAVA_HOME定义的jdk版本。所以也可以通过改变$JAVA_HOME来改变行为

或者在pom.xml中添加以下内容：

  
    
      org.apache.maven.plugins
      maven-compiler-plugin
      
        1.7
        1.7
      
    
  

7、SecurityException: Invalid signature file digest for Manifest main attribute

见第2点shade与超级包里面有一种更好的解决方案。
使用maven打包（尤其是uber包）时，可能出现以下错误：

Exception in thread "main" java.lang.SecurityException: Invalid signature file digest for Manifest main attributes
    at sun.security.util.SignatureFileVerifier.processImpl(SignatureFileVerifier.java:286)
    at sun.security.util.SignatureFileVerifier.process(SignatureFileVerifier.java:239)
    at java.util.jar.JarVerifier.processEntry(JarVerifier.java:317)
    at java.util.jar.JarVerifier.update(JarVerifier.java:228)
    at java.util.jar.JarFile.initializeVerifier(JarFile.java:348)
    at java.util.jar.JarFile.getInputStream(JarFile.java:415)
    at sun.misc.URLClassPath$JarLoader$2.getInputStream(URLClassPath.java:775)
    at sun.misc.Resource.cachedInputStream(Resource.java:77)
    at sun.misc.Resource.getByteBuffer(Resource.java:160)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:436)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

这是因为打包了一些元信息文件进包里面导致的，可以将其删除：

zip -d jarname.jar META-INF/*.RSA META-INF/*.DSA META-INF/*.SF

8、scala插件

如果maven项目中有scala代码，需要在pom.xml中添加以下内容：

    
    
         
            net.alchim31.maven
            scala-maven-plugin
            3.2.0
            
                
                    compile-scala
                    compile
                    
                        add-source
                        compile
                    
                
                
                    test-compile-scala
                    test-compile
                    
                        add-source
                        testCompile
                    
                
            
            
                2.11.8
            
        

9、自定义变量

定义时：

    UTF-8
    0.2

使用时：

com.lujinhong
lujinhong-commons
${project.version}

10、依赖本地项目

先将本地项目mvn install到本地，然后在项目中添加repo：

    
        in-project
        In Project Repo
        file:///Users/liaoliuqing/.m2/repository
    

最后就可以正常的使用dependency了，如：

       com.lujinhong
        lujinhong-commons-hadoop
        ${project.version}

11、关于version的说明：不要用变成充当version

尤其是依赖于父项目的子模块，不然会有各种问题：http://stackoverflow.com/questions/1981151/warning-on-using-project-parent-version-as-the-version-of-a-module-in-maven-3

[WARNING] ‘version’ contains an expression but should be a constant. @ com.lujinhong:lujinhong-commons:${project.version}, /Users/liaoliuqing/99_Project/lujinhong-commons/pom.xml, line 9, column 11