2_09_XPath

afomin-basejava · afomin-basejava · commit ae3f45ef4d97 · 2023-05-25T09:30:15.000+03:00
diff --git a/src/main/java/ru/javaops/masterjava/xml/util/XPathProcessor.java b/src/main/java/ru/javaops/masterjava/xml/util/XPathProcessor.java
@@ -0,0 +1,58 @@
+package ru.javaops.masterjava.xml.util;
+
+import org.w3c.dom.Document;
+import org.xml.sax.SAXException;
+
+import javax.xml.namespace.QName;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathExpression;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+import java.io.IOException;
+import java.io.InputStream;
+
+public class XPathProcessor {
+    private static final DocumentBuilderFactory DOCUMENT_FACTORY = DocumentBuilderFactory.newInstance();
+    private static final DocumentBuilder DOCUMENT_BUILDER;
+
+    private static final XPathFactory XPATH_FACTORY = XPathFactory.newInstance();
+    private static final XPath XPATH = XPATH_FACTORY.newXPath();
+
+    static {
+        DOCUMENT_FACTORY.setNamespaceAware(true);
+        try {
+            DOCUMENT_BUILDER = DOCUMENT_FACTORY.newDocumentBuilder();
+        } catch (ParserConfigurationException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    private final Document doc;
+
+    public XPathProcessor(InputStream is) {
+        try {
+            doc = DOCUMENT_BUILDER.parse(is);
+        } catch (SAXException | IOException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    public static synchronized XPathExpression getExpression(String exp) {
+        try {
+            return XPATH.compile(exp);
+        } catch (XPathExpressionException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    public <T> T evaluate(XPathExpression expression, QName type) {
+        try {
+            return (T) expression.evaluate(doc, type);
+        } catch (XPathExpressionException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+}
diff --git a/src/test/java/ru/javaops/masterjava/xml/util/XPathProcessorTest.java b/src/test/java/ru/javaops/masterjava/xml/util/XPathProcessorTest.java
@@ -0,0 +1,26 @@
+package ru.javaops.masterjava.xml.util;
+
+import com.google.common.io.Resources;
+import org.junit.Test;
+import org.w3c.dom.NodeList;
+
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpression;
+import java.io.InputStream;
+import java.util.stream.IntStream;
+
+public class XPathProcessorTest {
+    @Test
+    public void getCities() throws Exception {
+        try (InputStream is =
+                     Resources.getResource("payload.xml").openStream()) {
+            XPathProcessor processor = new XPathProcessor(is);
+            XPathExpression expression =
+                    XPathProcessor.getExpression("/*[name()='Payload']/*[name()='Cities']/*[name()='City']/text()");
+            NodeList nodes = processor.evaluate(expression, XPathConstants.NODESET);
+            IntStream.range(0, nodes.getLength()).forEach(
+                    i -> System.out.println(nodes.item(i).getNodeValue())
+            );
+        }
+    }
+}
