waluty - wersja XPath - początek

src/main/java/p20_xml/Waluty1_Dom.java

@@ -2,7 +2,6 @@ package p20_xml;
 
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
-import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 
 import javax.xml.parsers.DocumentBuilder;

src/main/java/p20_xml/Waluty2_XPath.java

+package p20_xml;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathFactory;
+import java.io.File;
+
+public class Waluty2_XPath {
+    // Wersja w swojej strukturze podobna do Waluty1_Dom, ale zamiast getElementsByTagName będziemy tu używać wyrażeń XPath
+
+    public static void main(String[] args) {
+        File plik = new File("pliki/waluty2023.xml");
+        String waluta = "EUR";
+
+        System.out.println("Startujemy");
+        long t1 = System.nanoTime();
+        try {
+            XPathFactory xpf = XPathFactory.newInstance();
+            XPath xpath = xpf.newXPath();
+
+            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
+            DocumentBuilder builder = dbf.newDocumentBuilder();
+            Document doc = builder.parse(plik);
+            long t2 = System.nanoTime();
+
+            double min = Double.MAX_VALUE, max = 0, sum = 0;
+            int count = 0;
+
+            NodeList tables = (NodeList) xpath.evaluate("//ExchangeRatesTable", doc, XPathConstants.NODESET);
+            final int n = tables.getLength();
+            for(int i = 0; i < n; i++) {
+                Node table = tables.item(i);
+                String effectiveDate = xpath.evaluate("EffectiveDate", table);
+                System.out.println(effectiveDate);
+                NodeList rates = (NodeList) xpath.evaluate("Rates/Rate", table, XPathConstants.NODESET);
+                final int m = rates.getLength();
+                for(int j = 0; j < m; j++) {
+                    Element rate = (Element) rates.item(j);
+                    String code = xpath.evaluate("Code", rate);
+                    if(code.equals(waluta)) {
+                        double mid = (Double) xpath.evaluate("Mid", rate, XPathConstants.NUMBER);
+                        count++;
+                        sum += mid;
+                        if(mid < min) min = mid;
+                        if(mid > max) max = mid;
+                    }
+                }
+            }
+            long t3 = System.nanoTime();
+            Runtime runtime = Runtime.getRuntime();
+            long pamiec = runtime.totalMemory() - runtime.freeMemory();
+
+            System.out.printf("Czas czytania pliku: %.6f s%n", (t2-t1) * 1e-9);
+            System.out.printf("Czas liczenia      : %.6f s%n", (t3-t2) * 1e-9);
+            System.out.printf("Czas łączny        : %.6f s%n", (t3-t1) * 1e-9);
+            System.out.printf("Zajęta pamięć      : %,d B%n", pamiec);
+            System.out.println("Count: " + count);
+            if(count > 0) {
+                System.out.println("Avg: " + (sum / count));
+                System.out.println("Min: " + min);
+                System.out.println("Max: " + max);
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}