如何來解讀這個XML文件結構

Question

我怎麼會去與JAXB解組此XML文件結構：

<document> 
    <properties> 
    <basic> 
     <property id="generationDate"> 
     <value>20150525</value> 
     </property> 
     <property id="hostAddress"> 
     <value>192.168.0.250</value> 
     </property> 
    </basic> 
    </properties> 
</document> 

段從Java類

import javax.xml.bind.annotation.*; 

    @XmlRootElement(name = "document") 
    @XmlAccessorType(XmlAccessType.FIELD) 
    class PDFDocument { 

     @XmlID 
     @XmlAttribute(name = "generationDate")  
     private String generationDate; 

片段從解組代碼：

PDFDocument doc = new PDFDocument(); 
      try { 
       JAXBContext jaxbContext = JAXBContext.newInstance(PDFDocument.class); 
       Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller(); 
       doc = (PDFDocument) jaxbUnmarshaller.unmarshal(new File(filePath)); 

      } catch (JAXBException ex) { 
       Logger.getLogger(FileFunctions.class.getName()).log(Level.SEVERE, null, ex); 
      } 

      System.out.println(doc.getGenerationDate()); 

但我不知道如何引用屬性的每個值。

Answer 1

好，所以基本上你的Java對象結構是錯誤的。您需要分析XML，然後您需要相應地構建Java對象結構。

如果你看看XML，你有一個文檔，在文檔中你有屬性，內部屬性的基本屬性等等。

所以同樣你需要有java類，文檔類，文檔內你需要有屬性類，在基類內等等。我已經在下面展示了這個類的結構，這樣你就可以得到一個想法。

文檔類 -

@XmlRootElement(name = "document") 
@XmlAccessorType(XmlAccessType.FIELD) 
public class PDFDocument { 

@XmlElement(name = "properties") 
private DocumentProperty documentProperty; 

public DocumentProperty getDocumentProperty() { 
    return documentProperty; 
} 

public void setDocumentProperty(DocumentProperty documentProperty) { 
    this.documentProperty = documentProperty; 
} 

@Override 
public String toString() { 
    return "PDFDocument{" + 
      "documentProperty=" + documentProperty + "\n" + 
      '}'; 
} 
} 

類來保存屬性 -

@XmlRootElement(name = "properties") 
@XmlAccessorType(XmlAccessType.FIELD) 
public class DocumentProperty { 

@XmlElement(name = "basic") 
private Basic basic; 

public Basic getBasic() { 
    return basic; 
} 

public void setBasic(Basic basic) { 
    this.basic = basic; 
} 

@Override 
public String toString() { 
    return "DocumentProperty{" + 
      "basic=" + basic + "\n" + 
      '}'; 
} 
} 

基本類 -

@XmlRootElement(name = "basic") 
@XmlAccessorType(XmlAccessType.FIELD) 
public class Basic { 

@XmlElementRef 
private List<Property> propertyList; 

public List<Property> getPropertyList() { 
    return propertyList; 
} 

public void setPropertyList(List<Property> propertyList) { 
    this.propertyList = propertyList; 
} 

@Override 
public String toString() { 
    return "Basic{" + 
      "propertyList=" + propertyList + "\n" + 
      '}'; 
} 
} 

地產類 -

@XmlRootElement(name = "property") 
@XmlAccessorType(XmlAccessType.FIELD) 
public class Property { 

@XmlAttribute(name = "id") 
private String id; 

@XmlElement(name = "value") 
private String value; 

public String getId() { 
    return id; 
} 

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

public String getValue() { 
    return value; 
} 

public void setValue(String value) { 
    this.value = value; 
} 

@Override 
public String toString() { 
    return "Property{" + 
      "id='" + id + "\n" + 
      ", value='" + value + "\n" + 
      '}'; 
} 
} 

Above Class結構適用於您提供的XML。但我想你將不得不改變這種結構，因爲除了基本類型之外，還有其他類型的文檔中的屬性。在這種情況下，我建議你具有抽象的Document Property類，並將其擴展到Basic和其他類型的Properties。

測試類 -

public class XmlTest { 

@Test 
public void testXml() throws Exception { 

    String xml = "<document>" + 
      " <properties>" + 
      " <basic>" + 
      "  <property id=\"generationDate\">" + 
      "  <value>20150525</value>" + 
      "  </property>\n" + 
      "  <property id=\"hostAddress\">" + 
      "  <value>192.168.0.250</value>" + 
      "  </property>" + 
      " </basic>" + 
      " </properties>" + 
      "</document>"; 

    try { 
     JAXBContext jaxbContext = JAXBContext.newInstance(PDFDocument.class); 
     Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller(); 
     PDFDocument document = (PDFDocument) jaxbUnmarshaller.unmarshal(new ByteArrayInputStream(xml.getBytes())); 


     System.out.println("PDF Document Structure -" +document.toString()); 


     for(Property property : document.getDocumentProperty().getBasic().getPropertyList()) { 
      if(property.getId().equals("generationDate")){ 
       System.out.println("Generation Date : "+property.getValue()); 
      } 
     } 
    } catch (JAXBException ex) { 
     ex.printStackTrace(); 
    } 
} 
} 

運行測試類產生以下結果。

PDFDocument{ 
documentProperty= 
DocumentProperty{ 
basic=Basic{ 
propertyList=[ 
Property{ 
id='generationDate 
, value='20150525 
}, 
Property{id='hostAddress 
, value='192.168.0.250 
}] 
} 
} 
} 

希望對您有所幫助。