BAEL-5755: Convert an XML file to CSV file
This commit is contained in:
Vladyslav Chernov
parent
fa06d77df8
commit
0bb7a8db27
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package com.baeldung.xml.xml2csv;
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import java.io.BufferedWriter;
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import java.io.File;
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import java.io.FileWriter;
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import java.io.IOException;
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import java.io.InputStream;
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import java.nio.file.Files;
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import java.nio.file.Paths;
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import javax.xml.stream.XMLInputFactory;
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import javax.xml.stream.XMLStreamConstants;
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import javax.xml.stream.XMLStreamReader;
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import javax.xml.transform.Result;
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import javax.xml.transform.Source;
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import javax.xml.transform.Transformer;
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import javax.xml.transform.TransformerException;
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import javax.xml.transform.TransformerFactory;
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import javax.xml.transform.stream.StreamResult;
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import javax.xml.transform.stream.StreamSource;
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public class Xml2CsvExample {
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private static final String BASE_PATH = "xml/src/main/resources/xml2csv/";
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private static final String STYLE_XSL = BASE_PATH + "style.xsl";
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private static final String DATA_XML = BASE_PATH + "data.xml";
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private static final String OUTPUT_CSV_XSTL = BASE_PATH + "output_xstl.csv";
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private static final String OUTPUT_CSV_STAX = BASE_PATH + "output_stax.csv";
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public static void main(String[] args) {
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try {
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convertXml2CsvXslt(STYLE_XSL, DATA_XML, OUTPUT_CSV_XSTL);
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convertXml2CsvStax(DATA_XML, OUTPUT_CSV_STAX);
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} catch (IOException | TransformerException e) {
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e.printStackTrace();
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}
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}
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protected static void convertXml2CsvXslt(String xslPath, String xmlPath, String csvPath) throws IOException, TransformerException {
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StreamSource styleSource = new StreamSource(new File(xslPath));
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Transformer transformer = TransformerFactory.newInstance()
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.newTransformer(styleSource);
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Source source = new StreamSource(new File(xmlPath));
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Result outputTarget = new StreamResult(new File(csvPath));
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transformer.transform(source, outputTarget);
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}
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protected static void convertXml2CsvStax(String xmlFilePath, String csvFilePath) throws IOException, TransformerException {
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XMLInputFactory inputFactory = XMLInputFactory.newInstance();
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try (InputStream in = Files.newInputStream(Paths.get(xmlFilePath)); BufferedWriter writer = new BufferedWriter(new FileWriter(csvFilePath))) {
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// Write header to CSV
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writer.write("bookstore_id,book_id,category,title,author_id,author_name,price\n");
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XMLStreamReader reader = inputFactory.createXMLStreamReader(in);
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String currentElement;
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StringBuilder csvRow = new StringBuilder();
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StringBuilder bookstoreInfo = new StringBuilder();
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while (reader.hasNext()) {
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int eventType = reader.next();
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switch (eventType) {
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case XMLStreamConstants.START_ELEMENT:
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currentElement = reader.getLocalName();
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if ("Bookstore".equals(currentElement)) {
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bookstoreInfo.setLength(0); // clear previous bookstore info
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bookstoreInfo.append(reader.getAttributeValue(null, "id"))
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.append(",");
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}
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if ("Book".equals(currentElement)) {
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csvRow.append(bookstoreInfo)
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.append(reader.getAttributeValue(null, "id"))
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.append(",")
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.append(reader.getAttributeValue(null, "category"))
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.append(",");
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}
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if ("Author".equals(currentElement)) {
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csvRow.append(reader.getAttributeValue(null, "id"))
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.append(",");
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}
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break;
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case XMLStreamConstants.CHARACTERS:
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if (!reader.isWhiteSpace()) {
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csvRow.append(reader.getText()
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.trim())
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.append(",");
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}
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break;
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case XMLStreamConstants.END_ELEMENT:
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if ("Book".equals(reader.getLocalName())) {
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// remove the last comma and add a newline
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csvRow.setLength(csvRow.length() - 1);
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csvRow.append("\n");
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writer.write(csvRow.toString());
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// Reset the StringBuilder for the next row
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csvRow.setLength(0);
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}
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break;
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}
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}
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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@ -0,0 +1,26 @@
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<?xml version="1.0"?>
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<Bookstores>
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<Bookstore id="S001">
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<Books>
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<Book id="B001" category="Fiction">
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<Title>Death and the Penguin</Title>
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<Author id="A001">Andrey Kurkov</Author>
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<Price>10.99</Price>
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</Book>
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<Book id="B002" category="Poetry">
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<Title>Kobzar</Title>
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<Author id="A002">Taras Shevchenko</Author>
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<Price>8.50</Price>
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</Book>
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</Books>
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</Bookstore>
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<Bookstore id="S002">
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<Books>
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<Book id="B003" category="Novel">
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<Title>Voroshilovgrad</Title>
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<Author id="A003">Serhiy Zhadan</Author>
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<Price>12.99</Price>
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</Book>
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</Books>
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</Bookstore>
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</Bookstores>
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@ -0,0 +1,21 @@
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<?xml version="1.0"?>
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<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
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<xsl:output method="text" omit-xml-declaration="yes" indent="no"/>
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<xsl:template match="/">
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<xsl:text>bookstore_id,book_id,category,title,author_id,author_name,price</xsl:text>
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<xsl:text>
</xsl:text>
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<xsl:for-each select="//Bookstore">
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<xsl:variable name="bookstore_id" select="@id"/>
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<xsl:for-each select="./Books/Book">
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<xsl:variable name="book_id" select="@id"/>
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<xsl:variable name="category" select="@category"/>
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<xsl:variable name="title" select="Title"/>
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<xsl:variable name="author_id" select="Author/@id"/>
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<xsl:variable name="author_name" select="Author"/>
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<xsl:variable name="price" select="Price"/>
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<xsl:value-of select="concat($bookstore_id, ',', $book_id, ',', $category, ',', $title, ',', $author_id, ',', $author_name, ',', $price)"/>
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<xsl:text>
</xsl:text>
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</xsl:for-each>
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</xsl:for-each>
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</xsl:template>
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</xsl:stylesheet>
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@ -0,0 +1,155 @@
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package com.baeldung.xml.xml2csv;
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import static org.junit.jupiter.api.Assertions.assertFalse;
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import static org.junit.jupiter.api.Assertions.assertNotNull;
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import static org.junit.jupiter.api.Assertions.assertThrows;
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import static org.junit.jupiter.api.Assertions.assertTrue;
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import static org.junit.jupiter.api.Assertions.fail;
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import java.io.BufferedReader;
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import java.io.File;
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import java.io.FileReader;
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import java.io.IOException;
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import java.nio.file.Files;
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import java.nio.file.Paths;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import javax.xml.transform.TransformerException;
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import org.junit.jupiter.api.AfterEach;
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import org.junit.jupiter.api.Test;
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public class Xml2CsvExampleUnitTest {
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private static final String BASE_PATH = "src/main/resources/xml2csv/";
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private static final String STYLE_XSL = BASE_PATH + "style.xsl";
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private static final String DATA_XML = BASE_PATH + "data.xml";
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private static final String TEMP_OUTPUT_CSV = BASE_PATH + "tempOutput.xml";
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@AfterEach
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public void teardown() {
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new File(TEMP_OUTPUT_CSV).delete();
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}
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@Test
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public void whenConvertXml2CsvXslt_thenCsvFileIsCreated() throws IOException, TransformerException {
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Xml2CsvExample.convertXml2CsvXslt(STYLE_XSL, DATA_XML, TEMP_OUTPUT_CSV);
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File csvFile = new File(TEMP_OUTPUT_CSV);
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assertTrue(csvFile.exists());
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}
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@Test
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public void whenConvertXml2CsvStax_thenCsvFileIsCreated() throws IOException, TransformerException {
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Xml2CsvExample.convertXml2CsvStax(DATA_XML, TEMP_OUTPUT_CSV);
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File csvFile = new File(TEMP_OUTPUT_CSV);
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assertTrue(csvFile.exists());
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}
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@Test
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public void whenConvertXml2CsvXslt_thenCsvFileIsNotEmpty() throws IOException, TransformerException {
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Xml2CsvExample.convertXml2CsvXslt(STYLE_XSL, DATA_XML, TEMP_OUTPUT_CSV);
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File csvFile = new File(TEMP_OUTPUT_CSV);
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BufferedReader reader = new BufferedReader(new FileReader(csvFile));
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String firstLine = reader.readLine();
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assertNotNull(firstLine);
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assertFalse(firstLine.isEmpty());
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reader.close();
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}
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@Test
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public void whenConvertXml2CsvStax_thenCsvFileIsNotEmpty() throws IOException, TransformerException {
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Xml2CsvExample.convertXml2CsvStax(DATA_XML, TEMP_OUTPUT_CSV);
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File csvFile = new File(TEMP_OUTPUT_CSV);
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BufferedReader reader = new BufferedReader(new FileReader(csvFile));
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String firstLine = reader.readLine();
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assertNotNull(firstLine);
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assertFalse(firstLine.isEmpty());
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reader.close();
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}
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@Test
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public void whenConvertXml2CsvXsltWithWrongXSL_thenThrowsException() {
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String xslWrongPath = BASE_PATH + "wrongFile.xsl";
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assertThrows(TransformerException.class, () -> Xml2CsvExample.convertXml2CsvXslt(xslWrongPath, DATA_XML, TEMP_OUTPUT_CSV));
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}
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@Test
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public void whenConvertXml2CsvXslt_thenCsvMatchesPattern() throws IOException, TransformerException {
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String headerPattern = "^bookstore_id,book_id,category,title,author_id,author_name,price$";
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String dataPattern = "^[A-Z0-9]+,[A-Z0-9]+,[a-zA-Z]+,[a-zA-Z0-9\\s]+,[A-Z0-9]+,[a-zA-Z\\s]+,\\d+(\\.\\d{2})?$";
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Xml2CsvExample.convertXml2CsvXslt(STYLE_XSL, DATA_XML, TEMP_OUTPUT_CSV);
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File csvFile = new File(TEMP_OUTPUT_CSV);
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try(BufferedReader reader = new BufferedReader(new FileReader(csvFile))) {
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String line;
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boolean isFirstLine = true;
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while ((line = reader.readLine()) != null) {
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if (isFirstLine) {
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assertTrue(line.matches(headerPattern), "Header does not match pattern");
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isFirstLine = false;
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} else {
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assertTrue(line.matches(dataPattern), "Data line does not match pattern");
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}
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}
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}
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}
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@Test
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public void whenConvertXml2Stax_thenCsvMatchesPattern() throws IOException, TransformerException {
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String headerPattern = "^bookstore_id,book_id,category,title,author_id,author_name,price$";
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String dataPattern = "^[A-Z0-9]+,[A-Z0-9]+,[a-zA-Z]+,[a-zA-Z0-9\\s]+,[A-Z0-9]+,[a-zA-Z\\s]+,\\d+(\\.\\d{2})?$";
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Xml2CsvExample.convertXml2CsvStax(DATA_XML, TEMP_OUTPUT_CSV);
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File csvFile = new File(TEMP_OUTPUT_CSV);
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try(BufferedReader reader = new BufferedReader(new FileReader(csvFile))) {
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String line;
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boolean isFirstLine = true;
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while ((line = reader.readLine()) != null) {
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if (isFirstLine) {
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assertTrue(line.matches(headerPattern), "Header does not match pattern");
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isFirstLine = false;
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} else {
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assertTrue(line.matches(dataPattern), "Data line does not match pattern");
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}
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}
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}
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}
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@Test
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public void whenConcurrentConversion_thenNoErrors() throws InterruptedException {
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int numThreads = 10;
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ExecutorService service = Executors.newFixedThreadPool(numThreads);
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CountDownLatch latch = new CountDownLatch(numThreads);
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for (int i = 0; i < numThreads; i++) {
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final int threadId = i;
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service.execute(() -> {
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String threadSpecificOutputCsv = BASE_PATH + "tempOutput" + threadId + ".csv";
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try {
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Xml2CsvExample.convertXml2CsvXslt(STYLE_XSL, DATA_XML, threadSpecificOutputCsv);
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assertTrue(Files.exists(Paths.get(threadSpecificOutputCsv)), "File should exist");
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} catch (IOException | TransformerException e) {
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fail("Exception should not be thrown: " + e.getMessage());
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} finally {
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new File(threadSpecificOutputCsv).delete();
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latch.countDown();
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}
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});
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}
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latch.await();
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}
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}
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