Parse XML Simple String using Java XPath

Question

I have XML String like this

<resp><status>good</status><msg>hi</msg></resp> 

I follow this help

Simplest way to query XML in Java

MyCode:

public static void main(String args[]) {      String xml = "<resp><status>good</status><msg>hi</msg></resp>";      XPathFactory xpathFactory = XPathFactory.newInstance();     XPath xpath = xpathFactory.newXPath();      InputSource source = new InputSource(new StringReader(xml));      String status = "";     String msg = "";     try {         status = (String) xpath.evaluate("/resp/status", source,XPathConstants.STRING);         msg = (String) xpath.evaluate("/resp/msg", source,XPathConstants.STRING);     } catch (Exception e) {         e.printStackTrace();     }      System.out.println("status=" + status);     System.out.println("Message=" + msg);   } 

I want to get msg node value but i got exception

java.io.IOException: Stream closed at java.io.StringReader.ensureOpen(StringReader.java:39) at java.io.StringReader.read(StringReader.java:73) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(XMLEntityScanner.java:1742) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.arrangeCapacity(XMLEntityScanner.java:1619) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.skipString(XMLEntityScanner.java:1657) at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(XMLVersionDetector.java:193) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:771) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107) at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:225) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283) at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.evaluate(XPathImpl.java:468) at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.evaluate(XPathImpl.java:515) at Parsing.main(Parsing.java:25)--------------- linked to ------------------ javax.xml.xpath.XPathExpressionException at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.evaluate(XPathImpl.java:475) at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.evaluate(XPathImpl.java:515) at Parsing.main(Parsing.java:25) Caused by: java.io.IOException: Stream closed at java.io.StringReader.ensureOpen(StringReader.java:39) at java.io.StringReader.read(StringReader.java:73) at     com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(XMLEntityScanner.java:1742) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.arrangeCapacity(XMLEntityScanner.java:1619) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.skipString(XMLEntityScanner.java:1657) at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(XMLVersionDetector.java:193) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:771) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107) at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:225) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283) at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.evaluate(XPathImpl.java:468) ... 2 more 

I am not going to use some external library for this simple task. please guide me how to get other node's values. Thanks

Answer 1

You can't reuse the same InputSource for multiple evaluate() invocations because it's automatically closed. Hence you're getting the Stream closed IO exception. Try this

InputSource source1 = new InputSource(new StringReader(xml)); InputSource source2 = new InputSource(new StringReader(xml));  String msg = xpath.evaluate("/resp/msg", source); String status = xpath.evaluate("/resp/status", source2);  System.out.println("msg=" + msg + ";" + "status=" + status); 

EDIT:
A better approach would be to use a DocumentBuilderFactory to parse your XML and build a Document first (using JAXP's DOM APIs) which can then be reused across several XPath evaluations.

String xml = "<resp><status>good</status><msg>hi</msg></resp>";  InputSource source = new InputSource(new StringReader(xml));  DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.parse(source);  XPathFactory xpathFactory = XPathFactory.newInstance(); XPath xpath = xpathFactory.newXPath();  String msg = xpath.evaluate("/resp/msg", document); String status = xpath.evaluate("/resp/status", document);  System.out.println("msg=" + msg + ";" + "status=" + status);