如何在解析复杂 XML 时尽量减少 XMLStreamReader 中 if else if 的使用

Question

我有示例 XML 数据，我想将其转换为简单的 XML 形式。

我必须根据主要 XML 数据中某些元素值的出现来创建多个 XML 数据。

逻辑嵌入在 XMLStreamReader 中。在这样做的同时，我必须使用多个 if else if 并且代码看起来很乱。如果 xml 标签包含增长，那么 if else if 逻辑似乎会增长。

是否有更好的设计模式来实现这个逻辑？
我必须将 XML 转换为可序列化对象，DOM 是更好的选择吗？

XML:

    <Bank createdTs="2014-11-26T16:50:13" xmlac = "http://www.trans.com/bank" xmlac:trans="http://www.trans.com/bank/dep/trans" xmlac:vref="http://www.trans.com/bank/security/verify">
<Transaction id="6f42cfee-ddd6-4d70-a6f7-a153d182c2b3" trans:type="deposit" trans:method="check">
    <UserRef status="Verify" vref:code="13" />
    <Account accountID="10002548" accountCategory="Checking">
        <TransactionRecord>
            <UserID>keith-kolmos</UserID>
            <Amount>4480</Amount>
            <LocationID>520</LocationID>
            <DateTimeStamp>2015-01-23T10:25:18</DateTimeStamp>
            <Comments>Check Verification Required</Comments>
        </TransactionRecord>
    </Account>
</Transaction>
<Transaction id="6f42cfee-ddd6-4d70-a6f7-a33d162c2b3" trans:type="withdraw" trans:method="cash">
    <Account accountID="10002548" accountCategory="Checking">
        <UserRef status="Complete" vref:code="10"/>
        <TransactionRecord>
            <UserID>zoe-danbur</UserID>
            <Amount>470</Amount>
            <LocationID>234</LocationID>
            <DateTimeStamp>2015-03-13T11:27:10</DateTimeStamp>
            <Comments/>
        </TransactionRecord>
    </Account>
</Transaction>
<Transaction id="6f42cfee-ddd6-4d70-a6f7-a0124d182c2b0" trans:type="deposit" trans:method="check">
    <Account accountID="10002548" accountCategory="Checking">
    <UserRef status="verify" vref:code="1"/>
        <TransactionRecord>
            <UserID>susan-wood</UserID>
            <Amount>585</Amount>
            <LocationID>127</LocationID>
            <DateTimeStamp>2015-03-25T09:20:32</DateTimeStamp>
            <Comments>Check Verified, photo ID presented</Comments>
        </TransactionRecord>
    </Account>
</Transaction>

XML DAO:

    public class BankDAO implements Serializable {
           private String accountID;
           private String accountCategory;
           private String transactionID;
           private String transactionType;
           private String transactionMethod;
           private String transactionStatus;
           private String transactionCode;
           private String userID;
           private String locationID;
           private String transactionAmount;
           private String dateTimeStamp;
           private String comments;

           //getters 
           //setters
           //toCustomXMLs
}

XML 解析逻辑实现：

public BankDAO parseXML(String xml) throws XMLStreamException, FactoryConfigurationError{
        XMLStreamReader xmlReader = XMLInputFactory.newInstance().createXMLStreamReader(new ByteArrayInputStream(xml.getBytes()));

        BankDAO bank = new BankDAO();

        String currentElement = "";
        while (xmlReader.hasNext()){
            int code = xmlReader.next();
            switch(code){
            case START_ELEMENT:
                currentElement = xmlReader.getLocalName();
                break;
            case CHARACTERS:
                if (currentElement.equalsIgnoreCase("Transaction")) {
                    bank.setTransactionID(xmlReader.getAttributeValue("http://www.trans.com/bank/dep/trans","id"));
                    bank.setTransactionType(xmlReader.getAttributeValue("http://www.trans.com/bank/dep/trans","type"));
                    bank.setTransactionMethod(xmlReader.getAttributeValue("http://www.trans.com/bank/dep/trans","method"));
                } else if (currentElement.equalsIgnoreCase("UserRef")) {
                    bank.setTransactionStatus(xmlReader.getAttributeValue(null,"status"));
                    bank.setTransactionCode(xmlReader.getAttributeValue("http://www.trans.com/bank/security/verify","code"));
                }else if (currentElement.equalsIgnoreCase("Account")){
                    bank.setAccountID(xmlReader.getAttributeValue(null,"accountID"));
                    bank.setAccountCategory(xmlReader.getAttributeValue(null,"accountCategory"));
                }else if (currentElement.equalsIgnoreCase("UserID")){
                    bank.setAccountID(xmlReader.getAttributeValue(null,"UserID"));
                }else if (currentElement.equalsIgnoreCase("Amount")){
                    bank.setTransactionAmount(xmlReader.getElementText());
                }else if (currentElement.equalsIgnoreCase("LocationID")){
                    bank.setLocationID(xmlReader.getElementText());
                }else if (currentElement.equalsIgnoreCase("DateTimeStamp")){
                    bank.setDateTimeStamp(xmlReader.getElementText());
                }else if (currentElement.equalsIgnoreCase("Comments")){
                    bank.setComments(xmlReader.getElementText());
                }
            }
        }
        return bank;
    }

Answer 1

尝试使用 Jaxb, which will convert the xml to java object. More basic example here

Answer 2

我建议您使用 JAXB and XmlAdapter 摘要 class。您所需要的只是提供链接。这将是良好的可读性和灵活的方法。示例：

public class DateXmlAdapter extends XmlAdapter<String, Date> {
    public static final String dateFormat = "yyyy-MM-dd'T'HH:mm:ss";

    @Override
    public Date unmarshal(String v) throws Exception {
        return new SimpleDateFormat(dateFormat).parse(v);
    }

    @Override
    public String marshal(Date v) throws Exception {
        return v == null ? "" : new SimpleDateFormat(dateFormat).format(v);
    }
}

此适配器会将日期从 String 表示形式转换为 java.util.Date。反之亦然。 JAXB 对象是这样的：

@XmlRootElement    
@XmlAccessorType(XmlAccessType.FIELD)
public class MyXMLObjectRepresentation {
     @XmlElement
     @XmlJavaTypeAdapter(DateXmlMigrateAdapter.class)
     private Date date;

     public Date getDate() {
         return date;
     }
}

您可以从这个JAXB Hello World. Some hints. Your IDE probably(or you can install plugin if doesn't) can generate xsd files from xml. Then you can use XJC tool开始生成java个文件。

如何在解析复杂 XML 时尽量减少 XMLStreamReader 中 if else if 的使用

How to minimize the use of if else if in XMLStreamReader while parsing complex XML

java

xml

if-statement

logic

xmlstreamreader