StAX Parser创建一个空的XML文件

问题描述

我正在学习Java解析器，现在我正尝试使用StAX Parser和XMLStreamWriter和StringWriter编写用于XML文件创建的代码。但是我不得不解决我的解析器创建一个空XML文件的问题。我认为问题出在使用for循环，但是我不知道该如何解决。 这是一段代码：

public class STAXParser4 {
...
public static void main(String[] args) throws ParserConfigurationException,SAXException,IOException,TransformerException { 
...
        try (FileWriter fileWriter = new FileWriter("STAX1ShoesShop.xml")){
            StringWriter stringWriter = new StringWriter();
            XMLOutputFactory xmlOutputFactory = XMLOutputFactory.newInstance();
            XMLStreamWriter xmlStreamWriter = xmlOutputFactory.createXMLStreamWriter(stringWriter);
            
            xmlStreamWriter.writeStartDocument();
            xmlStreamWriter.writeStartElement("ss:ShoesShop");
            ShoesShop shoesShop = new ShoesShop();
            
            for(Shoes shoes: shoesShop.getShoes()){ 
                xmlStreamWriter.writeStartElement("ss:shoes");
                xmlStreamWriter.writeAttribute("id",String.valueOf(shoes.getId()));
                
                xmlStreamWriter.writeStartElement("ss:title");
                xmlStreamWriter.writeCharacters(shoes.getTitle());
                xmlStreamWriter.writeEndElement();
                
                xmlStreamWriter.writeStartElement("ss:brand");
                xmlStreamWriter.writeCharacters(shoes.getBrand().toString());
                xmlStreamWriter.writeEndElement();
                
                xmlStreamWriter.writeStartElement("ss:category");
                xmlStreamWriter.writeCharacters(shoes.getCategory().toString());
                xmlStreamWriter.writeEndElement();
                
                xmlStreamWriter.writeStartElement("ss:season");
                xmlStreamWriter.writeCharacters(shoes.getSeason().toString());
                xmlStreamWriter.writeEndElement();
                
                xmlStreamWriter.writeStartElement("ss:price");
                xmlStreamWriter.writeCharacters(String.valueOf(shoes.getPrice()));
                xmlStreamWriter.writeEndElement();
                
                xmlStreamWriter.writeEndElement();
            } 
            xmlStreamWriter.writeEndElement();
            xmlStreamWriter.writeEndDocument();
            
            xmlStreamWriter.flush();
            xmlStreamWriter.close();
        } catch (XMLStreamException | IOException e) {
            e.printstacktrace();
        }
        
    }
}

这也是鞋类的java类

@XmlAccessorType(XmlAccesstype.FIELD)
@XmlType(name = "Shoes",propOrder = {
    "title","brand","category","season","gender","details","price"
})
public class Shoes
    extends Entity
{
    @XmlElement(required = true)
    protected String title;
    @XmlElement(required = true)
    @XmlSchemaType(name = "string")
    protected Brand brand;
    @XmlElement(required = true)
    @XmlSchemaType(name = "string")
    protected Category category;
    @XmlElement(required = true)
    @XmlSchemaType(name = "string")
    protected Season season;
    @XmlElement(required = true)
    protected Shoes.Gender gender;
    @XmlElement(required = true)
    protected Shoes.Details details;
    protected double price;
    @XmlAttribute(name = "stock",required = true)
    protected boolean stock;
    @XmlAttribute(name = "mostWanted")
    protected Boolean mostWanted;

    public String getTitle() {
        return title;
    }

    public void setTitle(String value) {
        this.title = value;
    }
    
    public Brand getBrand(){
        return brand;
    }
    
    public void setBrand(Brand value){
        this.brand = value;
    }
    
    public Category getCategory(){
        return category;
    }
    
    public void setCategory(Category value){
        this.category = value;
    }
    
    public Season getSeason(){
        return season;
    }
    
    public void setSeason(Season value) {
        this.season = value;
    }

    public Shoes.Gender getGender() {
        return gender;
    }

    public void setGender(Shoes.Gender value) {
        this.gender = value;
    }

    public Shoes.Details getDetails() {
        return details;
    }

    public void setDetails(Shoes.Details value) {
        this.details = value;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double value) {
        this.price = value;
    }

    public boolean isstock() {
        return stock;
    }

    public void setStock(boolean value) {
        this.stock = value;
    }

    public Boolean isMostWanted() {
        return mostWanted;
    }

    public void setMostWanted(Boolean value) {
        this.mostWanted = value;
    }

    @XmlAccessorType(XmlAccesstype.FIELD)
    @XmlType(name = "",propOrder = {

    })
    public static class Details {

        @XmlElement(required = true)
        protected String highlights;
        @XmlElement(required = true)
        protected String composition;

        public String getHighlights() {
            return highlights;
        }

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

        public String getComposition() {
            return composition;
        }

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

    }

    @XmlAccessorType(XmlAccesstype.FIELD)
    @XmlType(name = "",propOrder = {
        "\u043c\u0443\u0436\u0441\u043a\u043e\u0439Or\u0416\u0435\u043d\u0441\u043a\u0438\u0439"
    })
    public static class Gender {

        @XmlElementRefs({
            @XmlElementRef(name = "\u0436\u0435\u043d\u0441\u043a\u0438\u0439",namespace = "http://www.example.org/ShoesShop",type = JAXBElement.class,required = false),@XmlElementRef(name = "\u043c\u0443\u0436\u0441\u043a\u043e\u0439",required = false)
        })
        protected List<JAXBElement<String>> maleOrFemale;

        public List<JAXBElement<String>> getMaleOrFemale() {
            if (maleOrFemale == null) {
                maleOrFemale = new ArrayList<JAXBElement<String>>();
            }
            return this.maleOrFemale;
        }
    }
}

Shoes shoes的数据：shoesShop.getShoes我是从另一个XML文件获得的。这是此文件的片段：

<ss:ShoesShop xmlns:ss="http://www.example.org/ShoesShop" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://www.example.org/ShoesShop ShoesShop.xsd ">
      <ss:shoes id="1" stock="true">
        <ss:title>Baltrum</ss:title>
        <ss:brand>Gucci</ss:brand>
        <ss:category>Boots</ss:category>
        <ss:season>fall</ss:season>
        <ss:price>734.0</ss:price>
      </ss:shoes>
  <ss:shoes id="2" stock="true" mostWanted = "true">
    <ss:title>Amalfi</ss:title>
    <ss:brand>dior</ss:brand>
    <ss:category>Mules</ss:category>
    <ss:season>winter</ss:season>
    <ss:price>364.0</ss:price>
  </ss:shoes>
</ss:ShoesShop>

解决方法

问题是您正在将输出写入stringWriter，但它没有连接到输出文件。
尝试将stringWriter替换为fileWriter，您将看到xml写入输出文件：

    try (FileWriter fileWriter = new FileWriter("STAX1ShoesShop.xml")){
        XMLOutputFactory xmlOutputFactory = XMLOutputFactory.newInstance();
        XMLStreamWriter xmlStreamWriter = xmlOutputFactory.createXMLStreamWriter(fileWriter);