java - Jenkins 插件无法访问节点上的文件

Question

通过我自己的插件，我需要知道 Jenkins 节点的工作区中是否存在文件。但是找不到该文件，而该文件确实存在于节点上(D:\workspace\JOB_NAME\test.txt)。

public class MyBuilder extends Builder implements Serializable {

    private static final long serialVersionUID = 1L;
    
    public boolean perform(AbstractBuild<?, ?> build, Launcher launcher, BuildListener listener) 
            throws InterruptedException, IOException {
            
        FilePath fp = new FilePath(build.getWorkspace(), "test.txt");

        String result = fp.act(new FileCallable<String>() {
            private static final long serialVersionUID = 1L;

            @Override
            public String invoke(File file, VirtualChannel channel) throws IOException, InterruptedException {
                if (file.getAbsoluteFile().exists()){
                    return file.getName() + " exists.";
                } else {
                    return file.getName() + " doesn't exist.";
                }
            }
        });

        System.out.println("result: " + result);

结果:

FATAL: remote file operation failed: D:\workspace\JOB_NAME\test.txt at hudson.remoting.Channel@182752b:Node
hudson.util.IOException2: remote file operation failed: D:\workspace\JOB_NAME\test.txt at hudson.remoting.Channel@182752b:Node
    at hudson.FilePath.act(FilePath.java:900)
    at hudson.FilePath.act(FilePath.java:877)
    at com.company.tlb.proj.MyBuilder.perform(Unknown Source)
    at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19)
    at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:804)
    at hudson.model.Build$BuildExecution.build(Build.java:199)
    at hudson.model.Build$BuildExecution.doRun(Build.java:160)
    at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:586)
    at hudson.model.Run.execute(Run.java:1575)
    at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
    at hudson.model.ResourceController.execute(ResourceController.java:88)
    at hudson.model.Executor.run(Executor.java:237)
Caused by: java.io.IOException: Unable to serialize hudson.FilePath$FileCallableWrapper@18b91cb
    at hudson.remoting.UserRequest.serialize(UserRequest.java:166)
    at hudson.remoting.UserRequest.<init>(UserRequest.java:62)
    at hudson.remoting.Channel.call(Channel.java:671)
    at hudson.FilePath.act(FilePath.java:893)
    ... 11 more
Caused by: java.io.NotSerializableException: java.io.PrintStream
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1164)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:330)
    at hudson.remoting.UserRequest._serialize(UserRequest.java:155)
    at hudson.remoting.UserRequest.serialize(UserRequest.java:164)
    ... 14 more

我做错了什么？

链接:

• Making your plugin behave in distributed Jenkins
• Jenkins API: FilePath.java

Answer 1

您正在将匿名内部类传递给 act(...)它有一个对其父类的隐式引用，MyBuilder .我的猜测是即使MyBuilder工具 Serializable ，由于对另一个不是 Serializable 的对象的引用，它实际上不能被序列化(例如堆栈跟踪指示的 java.io.PrintStream)。

创建 FileCallable<String> 的实例一个静态内部类，用于摆脱对其父类的隐式引用:

private static class MyFileCallable implements FileCallable<String> {
  private static final long serialVersionUID = 1L;
  @Override
  public String invoke(File file, VirtualChannel channel) throws IOException, InterruptedException {
    if (file.getAbsoluteFile().exists()){
      return file.getName() + " exists.";
    } else {
      return file.getName() + " doesn't exist.";
    }
  }
}

然后改用它:

String result = fp.act(new MyFileCallable());

更新: 这是 Java 的 Nested Classes 的链接教程概述了内部类的实例与其封闭的外部类实例之间的关系:

An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance.

这也在 JLS ( §8.1.3 Inner Classes and Enclosing Instances) 中用更多技术术语进行了解释。

考虑到这一点，这句话来自 Serializable doc解释你为什么遇到 NotSerializableException :

When traversing a graph, an object may be encountered that does not support the Serializable interface. In this case the NotSerializableException will be thrown and will identify the class of the non-serializable object.