Utility to pretty print XML
Change-Id: I8241e2643d64f9a2104751c6afd164c1b716f145
diff --git a/utils/misc/src/main/java/org/onlab/util/XmlString.java b/utils/misc/src/main/java/org/onlab/util/XmlString.java
new file mode 100644
index 0000000..9ffc0e2
--- /dev/null
+++ b/utils/misc/src/main/java/org/onlab/util/XmlString.java
@@ -0,0 +1,127 @@
+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.util;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.transform.OutputKeys;
+import javax.xml.transform.Transformer;
+import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamResult;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathFactory;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.xml.sax.InputSource;
+import com.google.common.base.Supplier;
+import com.google.common.base.Suppliers;
+import com.google.common.io.CharSource;
+
+/**
+ * PrettyPrinted XML String.
+ */
+public class XmlString implements CharSequence {
+
+ private static final Logger log = LoggerFactory.getLogger(XmlString.class);
+
+ private final Supplier<String> prettyString;
+
+
+ /**
+ * Prettifies given XML String.
+ *
+ * @param xml input XML
+ * @return prettified input or input itself is input is not well-formed
+ */
+ public static CharSequence prettifyXml(CharSequence xml) {
+ return new XmlString(CharSource.wrap(xml));
+ }
+
+ XmlString(CharSource inputXml) {
+ prettyString = Suppliers.memoize(() -> prettyPrintXml(inputXml));
+ }
+
+ private String prettyPrintXml(CharSource inputXml) {
+ try {
+ Document document = DocumentBuilderFactory.newInstance()
+ .newDocumentBuilder()
+ .parse(new InputSource(inputXml.openStream()));
+
+ document.normalize();
+
+ XPath xPath = XPathFactory.newInstance().newXPath();
+ NodeList nodeList = (NodeList) xPath.evaluate("//text()[normalize-space()='']",
+ document,
+ XPathConstants.NODESET);
+
+ for (int i = 0; i < nodeList.getLength(); ++i) {
+ Node node = nodeList.item(i);
+ node.getParentNode().removeChild(node);
+ }
+
+ // Setup pretty print options
+ Transformer t = TransformerFactory.newInstance().newTransformer();
+ t.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
+ t.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
+ t.setOutputProperty(OutputKeys.INDENT, "yes");
+ t.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
+
+ // Return pretty print xml string
+ StringWriter strWriter = new StringWriter();
+ t.transform(new DOMSource(document), new StreamResult(strWriter));
+ return strWriter.toString();
+ } catch (Exception e) {
+ log.warn("Pretty printing failed", e);
+ try {
+ String rawInput = inputXml.read();
+ log.debug(" failed input: \n{}", rawInput);
+ return rawInput;
+ } catch (IOException e1) {
+ log.error("Failed to read from input", e1);
+ return inputXml.toString();
+ }
+ }
+ }
+
+ @Override
+ public int length() {
+ return toString().length();
+ }
+
+ @Override
+ public char charAt(int index) {
+ return toString().charAt(index);
+ }
+
+ @Override
+ public CharSequence subSequence(int start, int end) {
+ return toString().subSequence(start, end);
+ }
+
+ @Override
+ public String toString() {
+ return prettyString.get();
+ }
+
+}
diff --git a/utils/misc/src/test/java/org/onlab/util/XmlStringTest.java b/utils/misc/src/test/java/org/onlab/util/XmlStringTest.java
new file mode 100644
index 0000000..b09c44d
--- /dev/null
+++ b/utils/misc/src/test/java/org/onlab/util/XmlStringTest.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.util;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class XmlStringTest {
+
+ @Test
+ public void testToString() {
+ String input = "<root> <a some='foo '/><b attr='4' ><c>42</c></b></root>";
+ CharSequence xml = XmlString.prettifyXml(input);
+ String expected = "<root>\n"
+ + " <a some=\"foo \"/>\n"
+ + " <b attr=\"4\">\n"
+ + " <c>42</c>\n"
+ + " </b>\n"
+ + "</root>\n";
+ assertEquals(expected, xml.toString());
+ }
+
+ @Test
+ public void illFormed() {
+ String input = "<root> <a some='foo '/>";
+
+ assertEquals(input, XmlString.prettifyXml(input).toString());
+ }
+
+}