java - 解码后返回 null 和空 List

Question

我使用了这个 XSD:https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/sample-xsd-file-customers-and-orders1

这个 XML:https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/sample-xml-file-customers-and-orders-linq-to-xml-2

我使用 Jaxb 从 XSD 生成了 Java 类，我创建了 unmarshall 方法，但每个值都返回 null。请帮忙!

这是我的主要类(class):

        try {

            SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
            Schema xsdSchema = sf.newSchema(new File(%Here is the PATH% \\CustomerAndOrders.xsd"));

            JAXBContext jc = JAXBContext.newInstance(Root.class);

            Unmarshaller unmarshaller = jc.createUnmarshaller();
            unmarshaller.setSchema(xsdSchema);
            unmarshaller.setEventHandler(new MyValidationEventHandler());
            File file = new File("%Here is the PATH% \\ XMLTestFile.xml");
            System.out.println(file.getName());

            Root root = (Root) unmarshaller.unmarshal(file);
            CustomerType orderT = new CustomerType();
            Customers cust = new Customers();

            for (CustomerType cT : cust.getCustomer()) {
                System.out.println(cT.getContactName());
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    static class MyValidationEventHandler implements ValidationEventHandler {

        public boolean handleEvent(ValidationEvent event) {
            System.out.println("\nEVENT");
            System.out.println("SEVERITY:  " + event.getSeverity());
            System.out.println("MESSAGE:  " + event.getMessage());
            System.out.println("LINKED EXCEPTION:  " + event.getLinkedException());
            System.out.println("LOCATOR");
            System.out.println("    LINE NUMBER:  " + event.getLocator().getLineNumber());
            System.out.println("    COLUMN NUMBER:  " + event.getLocator().getColumnNumber());
            System.out.println("    OFFSET:  " + event.getLocator().getOffset());
            System.out.println("    OBJECT:  " + event.getLocator().getObject());
            System.out.println("    NODE:  " + event.getLocator().getNode());
            System.out.println("    URL:  " + event.getLocator().getURL());
            return true;
        }

    }

使用 Jaxb 生成的类:

package XMLBeans;

import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;


@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "customers",
    "orders"
})
@XmlRootElement(name = "Root")
public class Root {

    @XmlElement(name = "Customers", required = true)
    protected Root.Customers customers;
    @XmlElement(name = "Orders", required = true)
    protected Root.Orders orders;

    /**
     * Gets the value of the customers property.
     * 
     * @return
     *     possible object is
     *     {@link Root.Customers }
     *     
     */
    public Root.Customers getCustomers() {
        return customers;
    }

    /**
     * Sets the value of the customers property.
     * 
     * @param value
     *     allowed object is
     *     {@link Root.Customers }
     *     
     */
    public void setCustomers(Root.Customers value) {
        this.customers = value;
    }

    /**
     * Gets the value of the orders property.
     * 
     * @return
     *     possible object is
     *     {@link Root.Orders }
     *     
     */
    public Root.Orders getOrders() {
        return orders;
    }

    /**
     * Sets the value of the orders property.
     * 
     * @param value
     *     allowed object is
     *     {@link Root.Orders }
     *     
     */
    public void setOrders(Root.Orders value) {
        this.orders = value;
    }


    /**
     * <p>Java class for anonymous complex type.
     * 
     * <p>The following schema fragment specifies the expected content contained within this class.
     * 
     * <pre>
     * &lt;complexType>
     *   &lt;complexContent>
     *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
     *       &lt;sequence>
     *         &lt;element name="Customer" type="{}CustomerType" maxOccurs="unbounded" minOccurs="0"/>
     *       &lt;/sequence>
     *     &lt;/restriction>
     *   &lt;/complexContent>
     * &lt;/complexType>
     * </pre>
     * 
     * 
     */
    @XmlAccessorType(XmlAccessType.FIELD)
    @XmlType(name = "", propOrder = {
        "customer"
    })
    public static class Customers {

        @XmlElement(name = "Customer")
        protected List<CustomerType> customer;

        public List<CustomerType> getCustomer() {
            if (customer == null) {
                customer = new ArrayList<CustomerType>();
            }
            return this.customer;
        }

    }


    /**
     * <p>Java class for anonymous complex type.
     * 
     * <p>The following schema fragment specifies the expected content contained within this class.
     * 
     * <pre>
     * &lt;complexType>
     *   &lt;complexContent>
     *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
     *       &lt;sequence>
     *         &lt;element name="Order" type="{}OrderType" maxOccurs="unbounded" minOccurs="0"/>
     *       &lt;/sequence>
     *     &lt;/restriction>
     *   &lt;/complexContent>
     * &lt;/complexType>
     * </pre>
     * 
     * 
     */
    @XmlAccessorType(XmlAccessType.FIELD)
    @XmlType(name = "", propOrder = {
        "order"
    })
    public static class Orders {

        @XmlElement(name = "Order")
        protected List<OrderType> order;

        /**
         * Gets the value of the order property.
         * 
         * <p>
         * This accessor method returns a reference to the live list,
         * not a snapshot. Therefore any modification you make to the
         * returned list will be present inside the JAXB object.
         * This is why there is not a <CODE>set</CODE> method for the order property.
         * 
         * <p>
         * For example, to add a new item, do as follows:
         * <pre>
         *    getOrder().add(newItem);
         * </pre>
         * 
         * 
         * <p>
         * Objects of the following type(s) are allowed in the list
         * {@link OrderType }
         * 
         * 
         */
        public List<OrderType> getOrder() {
            if (order == null) {
                order = new ArrayList<OrderType>();
            }
            return this.order;
        }

    }

}

CustomerType 类

package XMLBeans;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlSchemaType;
import javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.adapters.CollapsedStringAdapter;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "CustomerType", propOrder = {
    "companyName",
    "contactName",
    "contactTitle",
    "phone",
    "fax",
    "fullAddress"
})
public class CustomerType {

    @XmlElement(name = "CompanyName", required = true)
    protected String companyName;
    @XmlElement(name = "ContactName", required = true)
    protected String contactName;
    @XmlElement(name = "ContactTitle", required = true)
    protected String contactTitle;
    @XmlElement(name = "Phone", required = true)
    protected String phone;
    @XmlElement(name = "Fax")
    protected String fax;
    @XmlElement(name = "FullAddress", required = true)
    protected AddressType fullAddress;
    @XmlAttribute(name = "CustomerID")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "token")
    protected String customerID;

    /**
     * Gets the value of the companyName property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getCompanyName() {
        return companyName;
    }

    /**
     * Sets the value of the companyName property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setCompanyName(String value) {
        this.companyName = value;
    }

    /**
     * Gets the value of the contactName property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getContactName() {
        return contactName;
    }

    /**
     * Sets the value of the contactName property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setContactName(String value) {
        this.contactName = value;
    }

    /**
     * Gets the value of the contactTitle property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getContactTitle() {
        return contactTitle;
    }

    /**
     * Sets the value of the contactTitle property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setContactTitle(String value) {
        this.contactTitle = value;
    }

    /**
     * Gets the value of the phone property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getPhone() {
        return phone;
    }

    /**
     * Sets the value of the phone property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setPhone(String value) {
        this.phone = value;
    }

    /**
     * Gets the value of the fax property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getFax() {
        return fax;
    }

    /**
     * Sets the value of the fax property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setFax(String value) {
        this.fax = value;
    }

    /**
     * Gets the value of the fullAddress property.
     * 
     * @return
     *     possible object is
     *     {@link AddressType }
     *     
     */
    public AddressType getFullAddress() {
        return fullAddress;
    }

    /**
     * Sets the value of the fullAddress property.
     * 
     * @param value
     *     allowed object is
     *     {@link AddressType }
     *     
     */
    public void setFullAddress(AddressType value) {
        this.fullAddress = value;
    }

    /**
     * Gets the value of the customerID property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getCustomerID() {
        return customerID;
    }

    /**
     * Sets the value of the customerID property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setCustomerID(String value) {
        this.customerID = value;
    }

}

这是我的示例 XML:

<?xml version="1.0" encoding="utf-8"?>  
<Root>  
  <Customers>  
    <Customer CustomerID="GREAL">  
      <CompanyName>Great Lakes Food Market</CompanyName>  
      <ContactName>Howard Snyder</ContactName>  
      <ContactTitle>Marketing Manager</ContactTitle>  
      <Phone>(503) 555-7555</Phone>  
      <FullAddress>  
        <Address>2732 Baker Blvd.</Address>  
        <City>Eugene</City>  
        <Region>OR</Region>  
        <PostalCode>97403</PostalCode>  
        <Country>USA</Country>  
      </FullAddress>  
    </Customer>  
  </Customers>  
  <Orders>  
    <Order>  
      <CustomerID>GREAL</CustomerID>  
      <EmployeeID>6</EmployeeID>  
      <OrderDate>1997-05-06T00:00:00</OrderDate>  
      <RequiredDate>1997-05-20T00:00:00</RequiredDate>  
      <ShipInfo ShippedDate="1997-05-09T00:00:00">  
        <ShipVia>2</ShipVia>  
        <Freight>3.35</Freight>  
        <ShipName>Great Lakes Food Market</ShipName>  
        <ShipAddress>2732 Baker Blvd.</ShipAddress>  
        <ShipCity>Eugene</ShipCity>  
        <ShipRegion>OR</ShipRegion>  
        <ShipPostalCode>97403</ShipPostalCode>  
        <ShipCountry>USA</ShipCountry>  
      </ShipInfo>  
    </Order>   
    <Order>  
      <CustomerID>LETSS</CustomerID>  
      <EmployeeID>4</EmployeeID>  
      <OrderDate>1998-02-12T00:00:00</OrderDate>  
      <RequiredDate>1998-03-12T00:00:00</RequiredDate>  
      <ShipInfo ShippedDate="1998-02-13T00:00:00">  
        <ShipVia>2</ShipVia>  
        <Freight>90.97</Freight>  
        <ShipName>Let's Stop N Shop</ShipName>  
        <ShipAddress>87 Polk St. Suite 5</ShipAddress>  
        <ShipCity>San Francisco</ShipCity>  
        <ShipRegion>CA</ShipRegion>  
        <ShipPostalCode>94117</ShipPostalCode>  
        <ShipCountry>USA</ShipCountry>  
      </ShipInfo>  
    </Order>  
  </Orders>  
</Root>

Answer 1

您的 JAXB 为客户生成的类在注释 @XmlType 的参数 name 下命名为 CustomerType，但在您创建的 xml 上提供简单命名为 Customer 的单个客户标签。

将 Java 类中的任何声明从 CustomerType 更改为 Customer

编辑:通过读取XSD文件，我发现它与XML文件的有效内容不一致:所以我想知道是否还有其他东西被破坏了？

编辑2:正如您在评论中所述，您可以在上述更改后正确地解码 xml 文件，但无法检索 for-each 循环中的数据:这是因为一个非常简单的问题:您正在迭代cust 被分配为 Customers 的全新实例，并且与在 root 内有效解码的内容无关。所以请重构主类的代码，更改:

Root root = (Root) unmarshaller.unmarshal(file);
CustomerType orderT = new CustomerType();
Customers cust = new Customers();
for (CustomerType cT : cust.getCustomer()) {
    System.out.println(cT.getContactName());
}

至:

Root root = (Root) unmarshaller.unmarshal(file);
for (CustomerType cT : root.getCustomers.getCustomer()) {
    System.out.println(cT.getContactName());
}