在循环（maven-embedder）中执行 MavenCli 时出错？

Question

当我在循环中执行maven命令时有什么问题？目标是更新包列表的 pom.xml 版本。第一次迭代，maven 执行正确（更新 pom.xml），但之后的所有项目都会出错。

for (String bundlePath: bundlesToUpdate)
{
    MavenCli cli = new MavenCli();
String[] arguments = {
    "-Dtycho.mode=maven", 
        "org.eclipse.tycho:tycho-versions-plugin:set-version", 
    "-DgenerateBackupPoms=false", 
    "-DnewVersion=" + version};
    int result = cli.doMain(arguments, bundlePath, System.out, System.err);
}

与代码相同的错误：

`MavenCli cli = new MavenCli();
for (String bundlePath: bundlesToUpdate) 
{
    String[] arguments = {
    "-Dtycho.mode=maven", 
    "org.eclipse.tycho:tycho-versions-plugin:set-version", 
    "-DgenerateBackupPoms=false", 
    "-DnewVersion=" + version};
int result = cli.doMain(arguments, bundlePath, System.out, System.err);
}`

第一次，没关系：

[main] INFO org.eclipse.tycho.versions.manipulation.PomManipulator -   pom.xml//project/version: 2.2.6-SNAPSHOT => 2.2.7-SNAPSHOT
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - ------------------------------------------------------------------------
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - Reactor Summary:
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - 
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - XXXX project   ....................... SUCCESS [  0.216 s]
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - com.sungard.valdi.bus.fixbroker.client.bnp ........ SKIPPED
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - XXX project Feature ...................... SKIPPED
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - ------------------------------------------------------------------------
[main] INFO org.apache.maven.cli.event.ExecutionEventLogger - BUILD SUCCESS

之后的错误是：

[main] ERROR org.apache.maven.cli.MavenCli - Error executing Maven.
[main] ERROR org.apache.maven.cli.MavenCli - java.util.NoSuchElementException
  role: org.apache.maven.eventspy.internal.EventSpyDispatcher
roleHint: 
[main] ERROR org.apache.maven.cli.MavenCli - Caused by: null
[main] ERROR org.apache.maven.cli.MavenCli - Error executing Maven.
[main] ERROR org.apache.maven.cli.MavenCli - java.util.NoSuchElementException
      role: org.apache.maven.eventspy.internal.EventSpyDispatcher
roleHint: 

Answer 1

我找到的解决方案是使用 Maven Invoker，它适用于相同的功能：

    public class MavenInvoker {

    public static void main(String[] args) throws IOException, NoHeadException, GitAPIException 
{
    MavenInvoker toto = new MavenInvoker();

    toto.updateVersionMavenInvoker("2.2.8-SNAPSHOT", "TECHNICAL\\WEB" );
}

private InvocationRequest request = new DefaultInvocationRequest();
private DefaultInvoker invoker = new DefaultInvoker();

public InvocationResult updateVersionMavenInvoker(String newVersion, String folderPath)
{
    InvocationResult result = null;
    request.setPomFile( new File(folderPath+"\\pom.xml" ) );

    String version =  "-DnewVersion="+newVersion;
    request.setGoals( Arrays.asList("-Dtycho.mode=maven", 
            "org.eclipse.tycho:tycho-versions-plugin:set-version", 
            "-DgenerateBackupPoms=false", 
            version) );
    try {
        result = invoker.execute( request );
    } catch (MavenInvocationException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return result;
}

}

Answer 2

这适用于我在自定义 maven 插件中（使用 Maven 3.5.0）：

ClassRealm classRealm = (ClassRealm) Thread.currentThread().getContextClassLoader();
MavenCli cli = new MavenCli(classRealm.getWorld());
cli.doMain( ... );

plexus Launcher sets the context class loader 到它的ClassRealm，它可以访问“全局”ClassWorld。

不确定该解决方案的稳定性如何，但目前看起来不错。

使用过的进口：

import org.codehaus.plexus.classworlds.ClassWorld;
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.apache.maven.cli.MavenCli;

Answer 3

更详细的解释请参见邮件主题：https://dev.eclipse.org/mhonarc/lists/sisu-users/msg00063.html

似乎正确的方法是在构造时给MainCli 一个ClassWorld 实例，以便它可以通过多次调用保持正确的状态。

例子：

final ClassWorld classWorld = new ClassWorld("plexus.core", getClass().getClassLoader());
MavenCli cli = new MavenCli(classWorld);
String[] arguments = {
    "-Dtycho.mode=maven", 
        "org.eclipse.tycho:tycho-versions-plugin:set-version", 
    "-DgenerateBackupPoms=false", 
    "-DnewVersion=" + version};
int result = cli.doMain(arguments, bundlePath, System.out, System.err);