在Java中使用SAX解析器的堆栈溢出错误

Question

所以我和朋友正在研究这个项目,我们一直在试图弄清楚如何从XML文件中的单个文本节点中提取值.他能够提出一些代码来提取我们正在寻找的文本节点,但是有一个小问题.当我运行以下代码时,它工作正常,并提取我们需要的...

JAVA CODE

import java.io.File;
import org.xml.sax.*;
import org.xml.sax.helpers.DefaultHandler;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

public class Test extends DefaultHandler 
{
    StringBuffer buffer;
    String heading;
    boolean inHeading;

    public static void main(String[] args)
    {
        try
        {
            Test saxNames = new Test();
            SAXParser parser = SAXParserFactory.newInstance().newSAXParser();

            parser.parse(new File("C:/Documents and Settings/user/workspace/Intern Project/Proposals/Converted Proposals/Extracted Items/ProposalOne.docx - Extracted Items/word/document.xml"), saxNames);

        }
        catch(Exception e)
        {
            e.printStackTrace(System.err);
        }
    }

    public void startElement(String uri, String localName, String qName, Attributes attrs)
    {
        if ("w:pStyle".equals(qName))
        {
            String val = attrs.getValue("w:val");

            if (val.contains("Heading"))
            {
                if (isHeading(val))
                {
                    System.out.println(val);
                    inHeading = true;
                }
            }
        }



        if("w:t".equals(qName))
        {
            String val = attrs.getValue("w:t");
            if (inHeading == true)
            {
                buffer = new StringBuffer();
            }
        } 
    }

    public void characters(char buff[], int offset, int length) throws SAXException
    {
        String s = new String(buff, offset, length);

        if(buffer != null)
        {
            buffer.append(s);
            heading = heading += s;
        }   
    }

    public void endElement(String uri, String localName, String qName)
    {
        buffer = null; 

        if ("w:p".equals(qName) && inHeading == true)
        {       
            System.out.println(heading);        

            heading = "";
            inHeading = false;      
        }   
    }

    private static boolean isHeading(String heading)
    {
        String headingNumber = heading.substring(7,8);
        String headingName = heading.substring(0,7);

        if (headingName.equals("Heading"))
        {
            if (headingNumber.equals("1") 
                    || headingNumber.equals("2")
                    || headingNumber.equals("3")
                    || headingNumber.equals("4")
                    || headingNumber.equals("5")
                    || headingNumber.equals("6"))
            {
                return true;
            }
        }

        return false; 
    }
}

但是,由于这只是我们正在开发的大型项目的一部分,我希望能够将其合并到驱动程序类中.因此,我希望能够将main方法转换为构造函数,因此当我更改时......

public static void main(String[] args)
        {
            try
            {
                Test saxNames = new Test();
                SAXParser parser = SAXParserFactory.newInstance().newSAXParser();

                parser.parse(new File("C:/Documents and Settings/user/workspace/Intern Project/Proposals/Converted Proposals/Extracted Items/ProposalOne.docx - Extracted Items/word/document.xml"), saxNames);

            }
            catch(Exception e)
            {
                e.printStackTrace(System.err);
            }
        }

至....

public Test()
        {
            try
            {
                Test saxNames = new Test();
                SAXParser parser = SAXParserFactory.newInstance().newSAXParser();

                parser.parse(new File("C:/Documents and Settings/user/workspace/Intern Project/Proposals/Converted Proposals/Extracted Items/ProposalOne.docx - Extracted Items/word/document.xml"), saxNames);

            }
            catch(Exception e)
            {
                e.printStackTrace(System.err);
            }
        }

当我尝试从我的驱动程序运行它时,我得到以下错误....

Exception in thread "main" java.lang.StackOverflowError
    at Test.<init>(Test.java:17)
    at Test.<init>(Test.java:17)
    at Test.<init>(Test.java:17)
    at Test.<init>(Test.java:17)
    at Test.<init>(Test.java:17)
        .
        .
        .
    at Test.<init>(Test.java:17)

我不知道为什么这样做.查看代码,我想我可能已经知道错误的来源.在构造函数中,它使用相同的名称实例化另一个构造函数--->因此它为什么在main方法中工作.但是,我不确定如何解决这个问题？

Answer 1

每次创建Test实例时,都会创建一个新的Test实例.看到错误？

在您的try语句中执行此操作:

// DON'T DO THIS: Test saxNames = new Test();

SAXParser parser = SAXParserFactory.newInstance().newSAXParser();

parser.parse(new File("blabla_filename.xml"), this);