XQuery-환경 설정

이 장에서는 로컬 개발 환경에서 XQuery 라이브러리를 설정하는 방법에 대해 설명합니다.

우리는 널리 사용되는 오픈 소스 독립형 XQuery 프로세서 Saxon Home Edition (Saxon-HE)을 사용하고 있습니다. 이 프로세서는 XSLT 2.0, XQuery 3.0 및 XPath 3.0을 지원하며 성능에 최적화되어 있습니다. Saxon XQuery 프로세서는 XML 데이터베이스없이 사용할 수 있습니다. 예제에서는 간단한 XML 문서를 데이터베이스로 사용합니다.

Saxon XQuery 프로세서를 사용하려면 애플리케이션의 클래스 경로에 saxon9he.jar, saxon9-test.jar, saxon9-unpack, saxon9-xqj.jar이 있어야합니다. 이 jar 파일은 다운로드 파일에서 사용할 수 있습니다.SaxonHE9-6-0-1J.zip Download SaxonHE9-6-0-1J.zip.

Example

We'll use the Java-based Saxon XQuery processor to test books.xqy, a file containing XQuery expression against our sample XML document, i.e., books.xml.

In this example, we'll see how to write and process a query to get the title elements of the books whose price is greater than 30.

books.xml

<?xml version="1.0" encoding="UTF-8"?>
<books>
   
   <book category="JAVA">
      <title lang="en">Learn Java in 24 Hours</title>
      <author>Robert</author>
      <year>2005</year>
      <price>30.00</price>
   </book>
   
   <book category="DOTNET">
      <title lang="en">Learn .Net in 24 hours</title>
      <author>Peter</author>
      <year>2011</year>
      <price>40.50</price>
   </book>
   
   <book category="XML">
      <title lang="en">Learn XQuery in 24 hours</title>
      <author>Robert</author>
      <author>Peter</author> 
      <year>2013</year>
      <price>50.00</price>
   </book>
   
   <book category="XML">
      <title lang="en">Learn XPath in 24 hours</title>
      <author>Jay Ban</author>
      <year>2010</year>
      <price>16.50</price>
   </book>
   
</books>

books.xqy

for $x in doc("books.xml")/books/book where $x/price>30
return $x/title

XQueryTester.java

package com.tutorialspoint.xquery;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

import javax.xml.xquery.XQConnection;
import javax.xml.xquery.XQDataSource;
import javax.xml.xquery.XQException;
import javax.xml.xquery.XQPreparedExpression;
import javax.xml.xquery.XQResultSequence;

import com.saxonica.xqj.SaxonXQDataSource;

public class XQueryTester {
   public static void main(String[] args){
      try {
         execute();
      }
      
      catch (FileNotFoundException e) {
         e.printStackTrace();
      }
      
      catch (XQException e) {
         e.printStackTrace();
      }
   }

   private static void execute() throws FileNotFoundException, XQException{
      InputStream inputStream = new FileInputStream(new File("books.xqy"));
      XQDataSource ds = new SaxonXQDataSource();
      XQConnection conn = ds.getConnection();
      XQPreparedExpression exp = conn.prepareExpression(inputStream);
      XQResultSequence result = exp.executeQuery();
      
      while (result.next()) {
         System.out.println(result.getItemAsString(null));
      }
   }	
}

Steps to Execute XQuery against XML

Step 1 − Copy XQueryTester.java to any location, say, E: > java
Step 2 − Copy books.xml to the same location, E: > java
Step 3 − Copy books.xqy to the same location, E: > java
Step 4 − Compile XQueryTester.java using console. Make sure you have JDK 1.5 or later installed on your machine and classpaths are configured. For details on how to use JAVA, see our JAVA Tutorial

E:\java\javac XQueryTester.java

Step 5 − Execute XQueryTester

E:\java\java XQueryTester

Output

You'll get the following result −

<title lang="en">Learn .Net in 24 hours</title>
<title lang="en">Learn XQuery in 24 hours</title>

Understanding Example

books.xml represents the sample data.
books.xqy represents the XQuery expression which is to be executed on books.xml. We'll understand the expression in details in next chapter.
XQueryTester, a Java-based XQuery executor program, reads the books.xqy, passes it to the XQuery expression processor, and executes the expression. Then the result is printed.