最简单的常春藤代码以编程方式从Maven中心检索依赖关系

Question

我发现常春藤API非常复杂。

什么是最简单的可能代码片段从Maven Central检索工件到使用Ivy 100％编程的特定本地目录（没有Ant，没有Xml文件，...）？

为了举例说明检索commons-logging：commons-logging：1.1：jar into/my/destination。

Answer 1

（和它的依赖）检索神器简单的方法是use ivy from the command-line

java -jar ivy.jar -dependency commons-logging commons-logging 1.1 -retrieve "/my/destination/[artifact](-[classifier]).[ext]" 

这将检索文件到目录“/我/目标”。

其他例子：

• using IVY dependencies manager programmatically
• Using Maven to download dependencies to a directory on the command line

Answer 2

我一直在使用的Ivy远程解决从Maven仓库的文物（和依赖性）。下面是一个下载一个工件（不依赖关系）的代码示例。

如果您需要依赖关系，则需要修改依赖关系描述符。

一些注意事项：

1. 常青藤使用一个缓存来存储以前提取的文物和自己的“常春藤翻译”（你会发现从Maven工件在高速缓存中得到的常春藤模块）

2. 一般概念是，你以编程方式创建一个常驻程序模块，它依赖于Maven存储库中存储的“伪模块”（即我认为解析器实现了一个映射）。

3. 一般而言，如果您想知道如何以编程方式使用Ivy，那么一个好的起点是主类org.apache.ivy.Main。

     public static void main(String[] args) throws Exception { 

     String groupId = "org.springframework"; 
     String artifactId = "spring-context-support"; 
     String version = "4.0.2.RELEASE"; 
     File out = new File("out"); 

     // create an ivy instance 
     IvySettings ivySettings = new IvySettings(); 
     ivySettings.setDefaultCache(new File("ivy/cache")); 

     // use the biblio resolver, if you consider resolving 
     // POM declared dependencies 
     IBiblioResolver br = new IBiblioResolver(); 
     br.setM2compatible(true); 
     br.setUsepoms(true); 
     br.setName("central"); 

     ivySettings.addResolver(br); 
     ivySettings.setDefaultResolver(br.getName()); 

     Ivy ivy = Ivy.newInstance(ivySettings); 

     // Step 1: you always need to resolve before you can retrieve 
     // 
     ResolveOptions ro = new ResolveOptions(); 
     // this seems to have no impact, if you resolve by module descriptor (in contrast to resolve by ModuleRevisionId) 
     ro.setTransitive(true); 
     // if set to false, nothing will be downloaded 
     ro.setDownload(true); 

     // 1st create an ivy module (this always(!) has a "default" configuration already) 
     DefaultModuleDescriptor md = DefaultModuleDescriptor.newDefaultInstance(
      // give it some related name (so it can be cached) 
      ModuleRevisionId.newInstance(
       groupId, 
       artifactId+"-envelope", 
       version 
      ) 
     ); 

     // 2. add dependencies for what we are really looking for 
     ModuleRevisionId ri = ModuleRevisionId.newInstance(
      groupId, 
      artifactId, 
      version 
     ); 
     // don't go transitive here, if you want the single artifact 
     DefaultDependencyDescriptor dd = new DefaultDependencyDescriptor(md, ri, false, false, false); 

     // map to master to just get the code jar. See generated ivy module xmls from maven repo 
     // on how configurations are mapped into ivy. Or check 
     // e.g. http://lightguard-jp.blogspot.de/2009/04/ivy-configurations-when-pulling-from.html 
     dd.addDependencyConfiguration("default", "master"); 
     md.addDependency(dd); 

     // now resolve 
     ResolveReport rr = ivy.resolve(md,ro); 
     if (rr.hasError()) { 
      throw new RuntimeException(rr.getAllProblemMessages().toString()); 
     } 

     // Step 2: retrieve 
     ModuleDescriptor m = rr.getModuleDescriptor(); 

     ivy.retrieve(
      m.getModuleRevisionId(), 
      out.getAbsolutePath()+"/[artifact](-[classifier]).[ext]", 
      new RetrieveOptions() 
       // this is from the envelop module 
       .setConfs(new String[]{"default"}) 
     ); 
    }