Detailed explanation of XML parsing in Java

Let’s briefly talk about the first three methods:

DOM method: Personal understanding is similar to .net’s XmlDocument, which is not efficient when parsing, takes up memory, and is not suitable for parsing large XML;

SAX method: event-based parsing. When a certain part of xml is parsed, a specific event will be triggered. You can define what to do when the event is triggered in a custom parsing class; I personally feel that it is very different. method, I wonder if there is a similar method under the .Net system?

StAX method: I personally understand that it is similar to the .net XmlReader method, which is highly efficient, takes up less memory, and is suitable for parsing large XML;

However, the SAX method has been used before. This article mainly introduces JAXB. Only the main code is posted here:

import java.util.ArrayList;
 import java.util.List;

 import org.xml.sax.Attributes;
 import org.xml.sax.SAXException;
 import org.xml.sax.helpers.DefaultHandler;

 public class ConfigParser extends DefaultHandler {
     private String currentConfigSection;

     public SysConfigItem sysConfig;
     public List<InterfaceConfigItem> interfaceConfigList;
     public List<FtpConfigItem> ftpConfigList;
     public List<AdapterConfigItem> adapterConfigList;

     public void startDocument() throws SAXException {
         sysConfig = new SysConfigItem();
         interfaceConfigList = new ArrayList<InterfaceConfigItem>();
         ftpConfigList = new ArrayList<FtpConfigItem>();
         adapterConfigList = new ArrayList<AdapterConfigItem>();
     }

     public void endDocument() throws SAXException {

     }

     public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
         if (qName.equalsIgnoreCase("Item") && attributes.getLength() > 0) {
             if (currentConfigSection.equalsIgnoreCase("SysConfigItem")) {
                 sysConfig = new SysConfigItem(attributes);
             } else if (currentConfigSection.equalsIgnoreCase("InterfaceConfigItems")) {
                 interfaceConfigList.add(new InterfaceConfigItem(attributes));
             } else if (currentConfigSection.equalsIgnoreCase("FtpConfigItems")) {
                 ftpConfigList.add(new FtpConfigItem(attributes));
             } else if (currentConfigSection.equalsIgnoreCase("AdapterConfigItems")) {
                 adapterConfigList.add(new AdapterConfigItem(attributes));
             }
         } else {
             currentConfigSection = qName;
         }
     }

     public void endElement(String uri, String localName, String qName) throws SAXException {

     }

     public void characters(char ch[], int start, int length) throws SAXException {

     }
 }

import java.lang.reflect.Field;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.xml.sax.Attributes;
public class ConfigItemBase {
    private static DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    public ConfigItemBase() {
    }
    /**
     * 目前只支持几种常用类型 如果需要支持其他类型，请修改这里的代码
     * 
     * @param attributes
     */
    public ConfigItemBase(Attributes attributes) {
        Class<?> cls = this.getClass();
        Field[] fields = cls.getDeclaredFields();
        for (Field field : fields) {
            String fieldType = field.getType().getSimpleName();
            for (int i = 0; i < attributes.getLength(); i++) {
                if (attributes.getQName(i).equalsIgnoreCase(field.getName())) {
                    field.setAccessible(true);
                    try {
                        if (fieldType.equalsIgnoreCase("String")) {
                            field.set(this, attributes.getValue(attributes.getQName(i)));
                        } else if (fieldType.equalsIgnoreCase("Integer")) {
                            field.set(this, Integer.valueOf(attributes.getValue(attributes.getQName(i))));
                        } else if (fieldType.equalsIgnoreCase("Double")) {
                            field.set(this, Double.valueOf(attributes.getValue(attributes.getQName(i))));
                        } else if (fieldType.equalsIgnoreCase("Date")) {
                            field.set(this, GetDate(attributes.getValue(attributes.getQName(i))));
                        } else {
                            System.out.println("Warning:Unhandler Field(" + field.getName() + "-" + fieldType + ")");
                        }
                    } catch (IllegalArgumentException e) {
                        e.printStackTrace();
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    }
                    break;
                }
            }
        }
    }
    public String toString() {
        String result = "";
        Class<?> cls = this.getClass();
        String classNameString = cls.getName();
        result += classNameString.substring(classNameString.lastIndexOf(&#39;.&#39;) + 1, classNameString.length()) + ":";
        Field[] fields = cls.getDeclaredFields();
        for (Field field : fields) {
            try {
                result += field.getName() + "=" + field.get(this) + ";";
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return result;
    }
    /**
     * 处理时间类型属性（时间格式要求为：yyyy-MM-dd hh:mm:ss）
     * 
     * @param dateString
     * @return
     */
    private static Date GetDate(String dateString) {
        Date date = null;
        try {
            date = dateFormat.parse(dateString);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return date;
    }
}

The following focuses on the most convenient one: JAXB (Java Architecture for XML Binding)
Here we use the more complex mobile BatchSyncOrderRelationReq interface XML as an example (I feel like I can solve this Basically enough for everyone), the message format is as follows (the CDATA content in SvcCont is the message body, which is disgusting):

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<InterBOSS>
    <Version>0100</Version>
    <TestFlag>0</TestFlag>
    <BIPType>
        <BIPCode>BIP2B518</BIPCode>
        <ActivityCode>T2101518</ActivityCode>
        <ActionCode>0</ActionCode>
    </BIPType>
    <RoutingInfo>
        <OrigDomain>BOSS</OrigDomain>
        <RouteType>routeType</RouteType>
        <Routing>
            <HomeDomain>XXXX</HomeDomain>
            <RouteValue>routeValue</RouteValue>
        </Routing>
    </RoutingInfo>
    <TransInfo>
        <SessionID>2013041017222313925676</SessionID>
        <TransIDO>2013041017222313925676</TransIDO>
        <TransIDOTime>20130410172223</TransIDOTime>
        <TransIDH></TransIDH>
        <TransIDHTime></TransIDHTime>
    </TransInfo>
    <SNReserve>
        <TransIDC></TransIDC>
        <ConvID></ConvID>
        <CutOffDay></CutOffDay>
        <OSNTime></OSNTime>
        <OSNDUNS></OSNDUNS>
        <HSNDUNS></HSNDUNS>
        <MsgSender></MsgSender>
        <MsgReceiver></MsgReceiver>
        <Priority></Priority>
        <ServiceLevel></ServiceLevel>
        <SvcContType></SvcContType>
    </SNReserve>
    <Response>
        <RspType>rspType</RspType>
        <RspCode>rspCode</RspCode>
        <RspDesc>rspDesc</RspDesc>
    </Response>
    <SvcCont><![CDATA[<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<batchSyncOrderRelationReq>
    <msgTransactionID>210001BIP2B518130410172223651627</msgTransactionID>
    <reqNum>2</reqNum>
    <reqBody>
        <oprNumb>210001BIP2B518130410172224341871</oprNumb>
        <subscriptionInfo>
            <oprTime>oprTime1</oprTime>
            <actionID>actionId1</actionID>
            <brand>brand1</brand>
            <effTime>effTime1</effTime>
            <expireTime>expireTime1</expireTime>
            <feeUser_ID>feeUserId1</feeUser_ID>
            <destUser_ID>destUserId1</destUser_ID>
            <actionReasonID>actionId1</actionReasonID>
            <servType>servType1</servType>
            <subServType>subServType1</subServType>
            <SPID>spId1</SPID>
            <SPServID>spServId1</SPServID>
            <accessMode>accessMode1</accessMode>
            <servParamInfo>
                <para_num>0</para_num>
                <para_info>
                    <para_name></para_name>
                    <para_value></para_value>
                </para_info>
            </servParamInfo>
            <feeType>feeType1</feeType>
        </subscriptionInfo>
    </reqBody>
    <reqBody>
        <oprNumb>210001BIP2B518130410172224420909</oprNumb>
        <subscriptionInfo>
            <oprTime>oprTime2</oprTime>
            <actionID>actionId2</actionID>
            <brand>brand2</brand>
            <effTime>effTime2</effTime>
            <expireTime>expireTime2</expireTime>
            <feeUser_ID>feeUserId2</feeUser_ID>
            <destUser_ID>destUserId2</destUser_ID>
            <actionReasonID>actionId2</actionReasonID>
            <servType>servType2</servType>
            <subServType>subServType2</subServType>
            <SPID>spId2</SPID>
            <SPServID>spServId2</SPServID>
            <accessMode>accessMode2</accessMode>
            <servParamInfo>
                <para_num>0</para_num>
                <para_info>
                    <para_name></para_name>
                    <para_value></para_value>
                </para_info>
            </servParamInfo>
            <feeType>feeType2</feeType>
        </subscriptionInfo>
    </reqBody>
</batchSyncOrderRelationReq>]]></SvcCont>
</InterBOSS>

The decoding code is as follows:

@XmlRootElement(name = "batchSyncOrderRelationReq")
 @XmlAccessorType(XmlAccessType.FIELD)
 public class BatchSyncOrderRelationReq extends BossMessage<BatchSyncOrderRelationReq> {

     @XmlElement(name = "msgTransactionID")
     private String msgTransactionId = "";

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

     @XmlElement(name = "reqBody")
     private List<BatchSyncOrderRelationReqBody> reqBodyList;

     public BatchSyncOrderRelationReq() {

     }

     public String getMsgTransactionId() {
         return this.msgTransactionId;
     }

     public void setMsgTransactionId(String msgTransactionId) {
         this.msgTransactionId = msgTransactionId;
     }

     public String getReqNum() {
         return this.reqNum;
     }

     public void setReqNum(String reqNum) {
         this.reqNum = reqNum;
     }

     public List<BatchSyncOrderRelationReqBody> getReqBodyList() {
         return this.reqBodyList;
     }

     public void setReqBodyList(List<BatchSyncOrderRelationReqBody> reqBodyList) {
         this.reqBodyList = reqBodyList;
     }

     @Override
     public BatchSyncOrderRelationReq Deserialized(String interBossXmlContent) throws BusinessException {
         try {
             // deserialized for head
             JAXBContext jaxbCxt4Head = JAXBContext.newInstance(MessageHead.class);
             Unmarshaller unmarshaller4Head = jaxbCxt4Head.createUnmarshaller();
             MessageHead head = (MessageHead) unmarshaller4Head.unmarshal(new StringReader(interBossXmlContent));

             // deserialized for SyncOrderRelationReq body
             JAXBContext jaxbCxt4Body = JAXBContext.newInstance(BatchSyncOrderRelationReq.class);
             Unmarshaller unmarshaller4Body = jaxbCxt4Body.createUnmarshaller();
             BatchSyncOrderRelationReq batchSyncOrderRelationReq = (BatchSyncOrderRelationReq) unmarshaller4Body.unmarshal(new StringReader(head.getSvcCont().trim()));
             batchSyncOrderRelationReq.setHead(head);

             return batchSyncOrderRelationReq;
         } catch (JAXBException e) {
             throw new BusinessException("SyncOrderRelationReq.Deserialized() Error!(" + interBossXmlContent + ")", e);
         }
     }

 }

@XmlAccessorType(XmlAccessType.FIELD)
public class BatchSyncOrderRelationReqBody {
    @XmlElement(name = "oprNumb")
    private String oprNumb = "";
    @XmlElement(name = "subscriptionInfo")
    private SubscriptionInfo subscriptionInfo;

    public BatchSyncOrderRelationReqBody(){

    }
    public BatchSyncOrderRelationReqBody(String oprNumb, SubscriptionInfo subscriptionInfo) {
        this.oprNumb = oprNumb;
        this.subscriptionInfo = subscriptionInfo;
    }
    public String getOprNumb() {
        return this.oprNumb;
    }
    public void setOprNumb(String oprNumb) {
        this.oprNumb = oprNumb;
    }
    public SubscriptionInfo getSubscriptionInfo() {
        return this.subscriptionInfo;
    }
    public void setSubscriptionInfo(SubscriptionInfo subscriptionInfo) {
        this.subscriptionInfo = subscriptionInfo;
    }
}

@XmlAccessorType(XmlAccessType.FIELD)
public class SubscriptionInfo {

    @XmlElement(name = "oprTime")
    private String oprTime = "";
    @XmlElement(name = "actionID")
    private String actionId = "";
    @XmlElement(name = "brand")
    private String brand = "";
    @XmlElement(name = "effTime")
    private String effTime = "";
    @XmlElement(name = "expireTime")
    private String expireTime = "";
    @XmlElement(name = "feeUser_ID")
    private String feeUserId = "";
    @XmlElement(name = "destUser_ID")
    private String destUserId = "";
    @XmlElement(name = "actionReasonID")
    private String actionReasonId = "";
    @XmlElement(name = "servType")
    private String servType = "";
    @XmlElement(name = "subServType")
    private String subServType = "";
    @XmlElement(name = "SPID")
    private String spId = "";
    @XmlElement(name = "SPServID")
    private String spServId = "";
    @XmlElement(name = "accessMode")
    private String accessMode = "";
    @XmlElement(name = "feeType")
    private String feeType = "";
    public SubscriptionInfo() {
    }

    public SubscriptionInfo(
            String oprTime,
            String actionId,
            String brand,
            String effTime,
            String expireTime,
            String feeUserId,
            String destUserId,
            String actionReasonId,
            String servType,
            String subServType,
            String spId,
            String spServId,
            String accessMode,
            String feeType) {
        this.oprTime = oprTime;
        this.actionId = actionId;
        this.brand = brand;
        this.effTime = effTime;
        this.expireTime = expireTime;
        this.feeUserId = feeUserId;
        this.destUserId = destUserId;
        this.actionReasonId = actionReasonId;
        this.servType = servType;
        this.subServType = subServType;
        this.spId = spId;
        this.spServId = spServId;
        this.accessMode = accessMode;
        this.feeType = feeType;
    }
    public String getOprTime() {
        return this.oprTime;
    }
    public void setOprTime(String oprTime) {
        this.oprTime = oprTime;
    }
    public String getActionId() {
        return this.actionId;
    }
    public void setActionId(String actionId) {
        this.actionId = actionId;
    }
    public String getBrand() {
        return this.brand;
    }
    public void setBrand(String brand) {
        this.brand = brand;
    }
    public String getEffTime() {
        return this.effTime;
    }
    public void setEffTime(String effTime) {
        this.effTime = effTime;
    }
    public String getExpireTime() {
        return this.expireTime;
    }
    public void setExpireTime(String expireTime) {
        this.expireTime = expireTime;
    }
    public String getFeeUserId() {
        return this.feeUserId;
    }
    public void setFeeUserId(String feeUserId) {
        this.feeUserId = feeUserId;
    }
    public String getDestUserId() {
        return this.destUserId;
    }
    public void setDestUserId(String destUserId) {
        this.destUserId = destUserId;
    }
    public String getActionReasonId() {
        return this.actionReasonId;
    }
    public void setActionReasonId(String actionReasonId) {
        this.actionReasonId = actionReasonId;
    }
    public String getServType() {
        return this.servType;
    }
    public void setServType(String servType) {
        this.servType = servType;
    }
    public String getSubServType() {
        return this.subServType;
    }
    public void setSubServType(String subServType) {
        this.subServType = subServType;
    }
    public String getSpId() {
        return this.spId;
    }
    public void setSpId(String spId) {
        this.spId = spId;
    }
    public String getSpServId() {
        return this.spServId;
    }
    public void setSpServId(String spServId) {
        this.spServId = spServId;
    }
    public String getAccessMode() {
        return this.accessMode;
    }
    public void setAccessMode(String accessMode) {
        this.accessMode = accessMode;
    }
    public String getFeeType() {
        return this.feeType;
    }
    public void setFeeType(String feeType) {
        this.feeType = feeType;
    }
}

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