JAXB 解组适用于 Java 1.8，但在 Java 1.7 中返回空值

Question

我需要我的服务器来解组 xml 文件。 我已经在我自己的运行 Java 1.8 的计算机上实现了这个类，它工作得很好。 但是，当我在运行 Java 1.7 的服务器上运行完全相同的代码时，会创建对象，但我得到“域”元素的空值。

我的代码在使用 JAXB 时可能不是理想的做法，但正如我在 java 1.8 上所说的那样，它完全符合我的需要。 有没有人知道这种行为的原因？ 任何帮助将不胜感激。

这是我试图解组的示例 xml 文件：

<planning:metadata xmlns:planning="http://planning.com">
  <domain id=numeric">
    <title xml:lang="en">The numeric formulation</title>
    <files_last_modified>2002-06-01T12:00:00</files_last_modified>
    <metadata_last_modified>2014-04-02T11:31:17.471631</metadata_last_modified>
    <published>2002-06-01T12:00:00</published>
    <link>http://ipc.icaps.org/</link>
    <requirements>
      <typing/>
      <fluents/>
    </requirements>
    <problems>
      <problem domain_file="domain.pddl" number="1" problem_file="p01.pddl"/>
      <problem domain_file="domain.pddl" number="2" problem_file="p02.pddl"/>
      <problem domain_file="domain.pddl" number="3" problem_file="p03.pddl"/>
      <problem domain_file="domain.pddl" number="4" problem_file="p04.pddl"/>
      <problem domain_file="domain.pddl" number="5" problem_file="p05.pddl"/>
      <problem domain_file="domain.pddl" number="6" problem_file="p06.pddl"/>
    </problems>
  </domain>
</planning:metadata>

这是java文件：

package server;

import javax.xml.bind.annotation.*;
import java.util.ArrayList;
import java.util.Date;

@XmlRootElement(name="metadata")
public class XmlDomain {

private XmlDomain.Domain domain;

public XmlDomain.Domain getDomain() {
    return domain;
}

@XmlElement
public void setDomain(XmlDomain.Domain domain) {
    this.domain = domain;
}

public static class Domain {
    private String id;
    private String title;
    private Date filesModifiedDate;
    private Date metaModifiedDate;
    private Date publishedDate;
    private String link;
    private Requirements requirements;
    private Problems problems;

    public String getId() {
        return id;
    }

    @XmlAttribute
    public void setId(String id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    @XmlElement
    public void setTitle(String title) {
        this.title = title;
    }

    public Date getFiles_last_modified() {
        return filesModifiedDate;
    }

    @XmlElement
    public void setFiles_last_modified(Date date) {
        filesModifiedDate = date;
    }

    public Date getMetadata_last_modified() {
        return metaModifiedDate;
    }

    @XmlElement
    public void setMetadata_last_modified(Date date) {
        metaModifiedDate = date;
    }

    public Date getPublished() {
        return publishedDate;
    }

    @XmlElement
    public void setPublished(Date date) {
        publishedDate = date;
    }

    public String getLink() {
        return link;
    }

    @XmlElement
    public void setLink(String link) {
        this.link = link;
    }

    public Requirements getRequirements() {
        return requirements;
    }

    @XmlElement
    public void setRequirements(Requirements requirements) {
        this.requirements = requirements;
    }

    public Problems getProblems() {
        return problems;
    }

    @XmlElement
    public void setProblems(Problems problems) {
        this.problems = problems;
    }

    public static class Requirements {

        // Strings representing domain requirements
        private String strips = null;
        private String typing = null;
        private String durative = null; // durative-actions
        private String fluents = null;
        private String timed = null; // time-initial-literal
        private String equality = null;
        private String inequalities = null; // duration_inequalities

        public String getStrips() {
            return strips;
        }

        @XmlElement(name = "strips")
        public void setStrips(String strips) {
            this.strips = strips;
        }

        public String getTyping() {
            return typing;
        }

        @XmlElement(name = "typing")
        public void setTyping(String typing) {
            this.typing = typing;
        }

        public String getDurative() {
            return durative;
        }

        @XmlElement(name = "durative-actions")
        public void setDurative(String durative) {
            this.durative = durative;
        }

        public String getFluents() {
            return fluents;
        }

        @XmlElement(name = "fluents")
        public void setFluents(String fluents) {
            this.fluents = fluents;
        }

        public String getTimed() {
            return timed;
        }

        @XmlElement(name = "timed-initial-literals")
        public void setTimed(String timed) {
            this.timed = timed;
        }

        public String getEquality() {
            return equality;
        }

        @XmlElement(name = "equality")
        public void setEquality(String equality) {
            this.equality = equality;
        }

        public String getInequalities() {
            return inequalities;
        }

        @XmlElement(name = "duration_inequalities")
        public void setInequalities(String inequalities) {
            this.inequalities = inequalities;
        }
    }

    public static class Problems {

        private ArrayList<Problem> problems;

        public ArrayList<Problem> getProblem() {
            return problems;
        }

        public void setProblem(ArrayList<Problem> problems) {
            this.problems = problems;
        }

        public static class Problem {

            private String domainFile;
            private int number;
            private String problemFile;

            public String getDomain_file() {
                return domainFile;
            }

            @XmlAttribute(name = "domain_file")
            public void setDomain_file(String domainFile) {
                this.domainFile = domainFile;
            }

            public int getNumber() {
                return number;
            }

            @XmlAttribute
            public void setNumber(int number) {
                this.number = number;
            }

            public String getProblem_file() {
                return problemFile;
            }

            @XmlAttribute(name = "problem_file")
            public void setProblem_file(String problemFile) {
                this.problemFile = problemFile;
            }

            public void addResult(Planner planner, double result) {
                resultMap.put(planner, result);
            }

            public double getResult(Planner planner) {
                return resultMap.get(planner);
            }

            public HashMap<Planner, Double> getResultMap() {
                return resultMap;
            }
        }
    }
}
}

和包文件：

@XmlSchema(
    namespace = "http://planning.com",
    elementFormDefault = XmlNsForm.QUALIFIED)

package server;

import javax.xml.bind.annotation.XmlNsForm;
import javax.xml.bind.annotation.XmlSchema;

Answer 1

根据您的 java 对象定义的架构，您的 XML 不正确。 架构中的所有内容都在http://planning.com命名空间下，但在 XML 中，该命名空间中定义的唯一元素是metadata 。 您需要：

• 将http://planning.com设置为默认命名空间。

  <metadata xmlns="http://planning.com"> <domain id=numeric"> ...

• 在所有元素上使用前缀

  <planning:metadata xmlns:planning="http://planning.com"> <planning:domain id=numeric"> ...

---

或者，如果可以假定 XML 是正确的但您的 Java 类不正确。 在这种情况下，只需从package-info.java删除@XmlSchema注释并使您的 Java 读取：

@XmlRootElement(name="metadata", namespace="http://planning.com")
public class XmlDomain {
    ...

---

正如评论者提到的那样，您在帖子中并没有真正提出问题，所以我不确定您是否询问为什么这在 1.8 而不是 1.7 中有效，并且知道 XML 不正确，或者只是不知道您有一些不好的 XML。

至于为什么这在 1.8 中有效对我来说仍然是个谜。 我会多加研究一下，并出于我自己的好奇心尝试找出原因。