SAX 解析器不调用起始元素答案

【问题标题】：SAX parser not calling start elementSAX 解析器不调用起始元素
【发布时间】：2015-08-16 16:40:57
【问题描述】：

我正在尝试执行以下代码，但我的 SAX 解析器没有调用 startElement 方法。

下面是我的代码：

package getTableStructure;

import java.util.List;
import java.io.*;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.SAXException;

import getTableStructure.DBdetails;

public class InformaticaObjectParser {
//H:/Eclipse_Workspace/GWM_SHARED_DEFINITION.XML
//H:/Eclipse_Workspace/InformaticaTableStruct/
public static void main(String[] args) {
    SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
    if (args.length == 2){
        System.out.println(args[1]);
        File opDir = new File(args[1].trim());
        if (opDir.exists() && opDir.isDirectory()){
            try {
                SAXParser saxParser = saxParserFactory.newSAXParser();
                System.out.println("Parser object created");
                MyHandler handler = new MyHandler();
                System.out.println(handler);
                saxParser.parse(new File(args[0]), handler);
                String outputDir = args[1].trim(); 
                System.out.println("I am here");
                List<DBdetails> TableList = handler.getEmpList();
                for(DBdetails db : TableList){
                    System.out.println("Table list from XML: " + TableList);
                    //BufferedWriter out = new BufferedWriter(new     FileWriter("H:/Eclipse_Workspace/TableStruct/" + tableName + ".csv"));
                    BufferedWriter out = new BufferedWriter(new FileWriter( outputDir + db.getName().trim()+"."+db.getSource().trim()+".csv"));
                        for (String k : db.dbdetail.keySet() ){
                        out.write(k+","+db.dbdetail.get(k));
                        out.newLine();
                        }
                        out.close();
                    }
                } 
                catch (ParserConfigurationException | SAXException | IOException e)     {
                    e.getMessage();
                }
            }
            else{
                System.out.println("2 arguments");
            }
        }
        else{
            System.out.println(" Number of arguments should be 2");
        }
    }
}

我的处理程序：

package getTableStructure;

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

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

import getTableStructure.DBdetails;

public class MyHandler extends DefaultHandler {

    private List<DBdetails> sourceList = null;
private DBdetails table = null;
public List<DBdetails> getEmpList() {
    return sourceList;
}
boolean bSource = false;
boolean bName = false;

@Override
public void startElement(String uri, String localName, String qName,
        Attributes attributes) throws SAXException {
    System.out.println("In MyHandler");
    System.out.println(qName);
    if (qName.equalsIgnoreCase("SOURCE")) {
        table = new DBdetails();
        String NAME = attributes.getValue("DBDNAME");
        String DbName = attributes.getValue("NAME");
        table.setName(NAME.trim());
        table.setSource(DbName.trim());
        if (sourceList == null)
            sourceList = new ArrayList<>();
    } else if (qName.equalsIgnoreCase("DBDNAME")) {
        bName = true;
    } else if (qName.equalsIgnoreCase("NAME")) {
        bSource = true;
    } else if (qName.equalsIgnoreCase("SOURCEFIELD")) {
        String details = (attributes.getValue("DATATYPE").trim()+","+attributes.getValue("PRECISION").trim()+","+attributes.getValue("SCALE").trim());
        this.table.dbdetail.put(attributes.getValue("NAME").trim(),
                details);
    }
}

@Override
public void endElement(String uri, String localName, String qName)
        throws SAXException {
    if (qName.equalsIgnoreCase("SOURCE")) {
        sourceList.add(table);
    }
}

@Override
public void characters(char ch[], int start, int length)
        throws SAXException {
    if (bName) {
        table.setName(new String(ch, start, length));
        bName = false;
    } else if (bSource) {
        table.setSource(new String(ch, start, length));
        bSource = false;
    }
}

}

以下是 XML：

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE POWERMART SYSTEM "powrmart.dtd">
<POWERMART CREATION_DATE="06/01/2015 11:44:43" REPOSITORY_VERSION="182.91">
<REPOSITORY NAME="PB_DEV02" VERSION="182" CODEPAGE="Latin1" DATABASETYPE="Sybase">
<FOLDER NAME="PB_DEFINITIONS" GROUP="" OWNER="E466701" SHARED="SHARED" DESCRIPTION="Place all PB source/target definitions here and use shortcuts for them in other PB_* folders." PERMISSIONS="rwx---rwx" UUID="6c90f1e5-b619-48fd-8ee1-5b0b136947ea">
    <SOURCE BUSINESSNAME ="" DATABASETYPE ="Sybase" DBDNAME ="database" DESCRIPTION ="" NAME ="table_name" OBJECTVERSION ="1" OWNERNAME ="dbo" VERSIONNUMBER ="1">
        <SOURCEFIELD BUSINESSNAME ="" DATATYPE ="varchar" DESCRIPTION ="" FIELDNUMBER ="1" FIELDPROPERTY ="0" FIELDTYPE ="ELEMITEM" HIDDEN ="NO" KEYTYPE ="PRIMARY KEY" LENGTH ="0" LEVEL ="0" NAME ="Col1" NULLABLE ="NOTNULL" OCCURS ="0" OFFSET ="0" PHYSICALLENGTH ="8" PHYSICALOFFSET ="0" PICTURETEXT ="" PRECISION ="8" SCALE ="0" USAGE_FLAGS =""/>
        <SOURCEFIELD BUSINESSNAME ="" DATATYPE ="varchar" DESCRIPTION ="" FIELDNUMBER ="2" FIELDPROPERTY ="0" FIELDTYPE ="ELEMITEM" HIDDEN ="NO" KEYTYPE ="NOT A KEY" LENGTH ="0" LEVEL ="0" NAME ="col2" NULLABLE ="NULL" OCCURS ="0" OFFSET ="0" PHYSICALLENGTH ="254" PHYSICALOFFSET ="8" PICTURETEXT ="" PRECISION ="254" SCALE ="0" USAGE_FLAGS =""/>
    </SOURCE>
    ..
    ..
    ..
</FOLDER>
</REPOSITORY>
</POWERMART>

几个月前我写这个项目时它工作得很好，但是当我现在打开它并尝试运行 InformaticaObjectParser 时，它没有调用 MyHandler 并且编程存在且没有给出任何错误。

如果您需要任何其他信息，请告诉我。

谢谢

【问题讨论】：

你没有贴出MyHandler的代码。
糟糕，我的错。我现在加了。感谢您指出:)
请缩进您的代码。很难阅读。
您有要发布的 XML 代码吗？也许在工作中 XML 有拼写错误或区分大小写...
尝试覆盖fatalError、error、warning方法看看你的文档是否有错误

标签： java xml-parsing sax saxparser

【解决方案1】：

尝试覆盖fatalError、error、warning方法，看看你的文档是否有错误

public class MyHandler extends DefaultHandler {
...

    @Override
    public void fatalError(SAXParseException e) throws SAXException {
        LOG.log(Level.SEVERE, e.getMessage(), e);
        throw new SAXException(e.getMessage());
    }

    @Override
    public void error(SAXParseException e) throws SAXException {
        LOG.log(Level.SEVERE, e.getMessage(), e);
        throw new SAXException(e.getMessage());
    }

    @Override
    public void warning(SAXParseException e) throws SAXException {
        LOG.log(Level.WARNING, e.getMessage(), e);
    }
...
}

【讨论】：

【解决方案2】：

您可以在不从 xml 中删除 DOCTYPE 的情况下使其工作。只需添加将 dtd 解析为空文档的实体解析器，如下所示：

saxParser.getXMLReader().setEntityResolver(new EntityResolver(){
    public InputSource resolveEntity(String publicId,String systemId){
        return new InputSource(new ByteArrayInputStream(new byte[0]));
    }
});

【讨论】：

【解决方案3】：

大家好，感谢您抽出宝贵时间。我得到了它。这是因为 xml 中的以下行。

<!DOCTYPE POWERMART SYSTEM "powrmart.dtd">

当我删除它时，代码可以正常工作。我不确定它的原因。有人可以解释一下吗？

再次感谢您的宝贵时间。

【讨论】：