Adding XpathDoc and test

src/main/java/knzn/xml/XpathDoc.java

@@ -0,0 +1,133 @@
+package knzn.xml;
+
+import java.io.ByteArrayInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+
+import org.xml.sax.InputSource;
+
+public final class XpathDoc {
+
+  public static class InputStreamInputSourceHolder implements InputSourceHolder {
+
+    private final InputStream stream;
+
+    public InputStreamInputSourceHolder(final InputStream stream) {
+      this.stream = stream;
+    }
+
+    public void close() {
+      try {
+        stream.close();
+      } catch (IOException e) {
+        LOGGER.log(Level.SEVERE, "Could not close stream", e);
+      }
+    }
+
+    public InputSource getInputSource() {
+      return new InputSource(stream);
+    }
+  }
+
+
+  private static class FileInputSourceHolder implements InputSourceHolder {
+
+    private final File file;
+    private InputStreamInputSourceHolder sourceHolder;
+
+    public FileInputSourceHolder(final File file) throws FileNotFoundException {
+      this.file = file;
+      if (!this.file.exists()) {
+        throw new FileNotFoundException("Not found: " + this.file);
+      }
+    }
+
+    public FileInputSourceHolder(final String xmlFile)
+            throws FileNotFoundException {
+      this(new File(xmlFile));
+    }
+
+    public void close() {
+      sourceHolder.close();
+    }
+
+    public InputSource getInputSource() {
+      try {
+        sourceHolder = new InputStreamInputSourceHolder(new FileInputStream(file));
+        return sourceHolder.getInputSource();
+      } catch (FileNotFoundException e) {
+        LOGGER.log(Level.SEVERE, "Could not find file", e);
+        throw new IllegalStateException(e);
+      }
+    }
+  }
+
+  private interface InputSourceHolder {
+    void close();
+
+    InputSource getInputSource();
+  }
+
+  private static class StringInputSourceHolder implements InputSourceHolder {
+
+    private final String text;
+    private InputStreamInputSourceHolder sourceHolder;
+
+    public StringInputSourceHolder(final String text) {
+      this.text = text;
+    }
+
+    public void close() {
+      sourceHolder.close();
+    }
+
+    public InputSource getInputSource() {
+      sourceHolder = new InputStreamInputSourceHolder(new ByteArrayInputStream(text.getBytes()));
+      return sourceHolder.getInputSource();
+    }
+
+  }
+
+  private static final Logger LOGGER = Logger.getLogger(XpathDoc.class
+          .getSimpleName());
+
+
+  public static XpathDoc newXpathDocFromFile(final File xmlFile)
+          throws FileNotFoundException {
+    return new XpathDoc(new FileInputSourceHolder(xmlFile));
+  }
+
+  public static XpathDoc newXpathDocFromFile(final String xmlFile)
+          throws FileNotFoundException {
+    return new XpathDoc(new FileInputSourceHolder(xmlFile));
+  }
+
+  public static XpathDoc newXpathDocFromString(final String xml) {
+    return new XpathDoc(new StringInputSourceHolder(xml));
+  }
+
+  private final XPath xPath;
+  private final InputSourceHolder inputSourceHolder;
+
+  private XpathDoc(final InputSourceHolder inputSourceHolder) {
+    this.inputSourceHolder = inputSourceHolder;
+    xPath = XPathFactory.newInstance().newXPath();
+  }
+
+  public String evaluate(final String expression)
+          throws XPathExpressionException {
+    final InputSource inputSource = inputSourceHolder.getInputSource();
+    final String result = xPath.evaluate(expression, inputSource);
+    inputSourceHolder.close();
+    return result;
+  }
+}

src/test/java/knzn/xml/XpathDocTest.java

@@ -0,0 +1,73 @@
+package knzn.xml;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.logging.Logger;
+
+import javax.xml.xpath.XPathExpressionException;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.IOUtils;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class XpathDocTest {
+
+  private static final Logger LOGGER = Logger.getLogger(XpathDocTest.class.getSimpleName());
+
+  private static final String TEST_XML = "/knzn/xml/xpath_test.xml";
+
+  private  static String readXmlFromFile() throws IOException {
+    final InputStream inputStream = XpathDocTest.class
+      .getResourceAsStream(TEST_XML);
+    final ByteArrayOutputStream bout = new ByteArrayOutputStream();
+    IOUtils.copy(inputStream, bout);
+
+    return new String(bout.toByteArray());
+  }
+
+  @Test
+  public void testNewXpathDocFromFile() throws XPathExpressionException, FileNotFoundException {
+    final File file = FileUtils.toFile(
+            XpathDocTest.class.getResource(TEST_XML));
+    final String xmlFile = file.getAbsolutePath();
+    LOGGER.info("xmlFile: " + xmlFile);
+
+    assertXpathDoc(
+            XpathDoc.newXpathDocFromFile(xmlFile));
+
+    assertXpathDoc(
+            XpathDoc.newXpathDocFromFile(file));
+  }
+
+
+  @Test
+  public void testNewXpathDocFromFileMissing() throws XPathExpressionException {
+    try {
+      XpathDoc.newXpathDocFromFile("missing_file.xml");
+      fail("Missing file exception not thrown");
+    } catch (FileNotFoundException e) {
+      assertEquals("Exception message not correct", 
+              "java.io.FileNotFoundException: Not found: missing_file.xml",
+              e.toString());
+    }
+  }
+
+  @Test
+  public void testNewXpathDocFromString() throws XPathExpressionException, IOException {
+    final String xml = readXmlFromFile();
+    assertXpathDoc(XpathDoc.newXpathDocFromString(xml));
+  }
+
+  private void assertXpathDoc(final XpathDoc xpathDoc) throws XPathExpressionException {
+    assertEquals("Expected name not found", "Tuck", 
+            xpathDoc.evaluate("//wonder_pets/wonder_pet[1]/name"));
+    assertEquals("Expected type not found", "turtle", 
+            xpathDoc.evaluate("//wonder_pets/wonder_pet[1]/@type"));
+  }
+}

src/test/resources/knzn/xml/xpath_test.xml

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+<wonder_pets>
+	<wonder_pet type="turtle">
+		<name>Tuck</name>
+	</wonder_pet>
+	<wonder_pet type="guinea pig">
+		<name>Lenny</name>
+	</wonder_pet>
+	<wonder_pet type="boy">
+		<name>Jonah</name>
+	</wonder_pet>
+</wonder_pets>