ch.inftec.ju.util.xml.XPathGetter Maven / Gradle / Ivy
package ch.inftec.ju.util.xml;
import java.util.ArrayList;
import java.util.List;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import ch.inftec.ju.util.JuRuntimeException;
/**
* Class providing a couple of helper functions to evaluate XPath expressions. There
* are a variety of return types like Strings, Longs, Arrays and other (relative)
* XPathGetters.
*
* @author tgdmemae
*
*/
public class XPathGetter {
/**
* XPath instance to work with XPaths.
*/
private static XPath xPath;
/**
* Node this getter works with, i.e. that matches '.'
*/
private Node node;
/**
* Creates a new XPathGetter with the specified node as a
* reference item.
* @param node Node that will match the XPath expression '.'
*/
public XPathGetter(Node node) {
this.node = node;
}
/**
* Gets an XPath instance to compile XPath expressions. There is only
* one static XPath instance created for all XPathGetters.
* @return XPath instance
*/
private XPath getXPath() {
if (XPathGetter.xPath == null) {
// Load the xPath instance to parse the document
XPathFactory xPathFactory = XPathFactory.newInstance();
XPathGetter.xPath = xPathFactory.newXPath();
}
return XPathGetter.xPath;
}
/**
* Evaluates the specified XPath expression.
* @param query XPath expression
* @return XPath result
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
private String evaluate(String query) throws JuRuntimeException {
try {
XPathExpression xPathExpression = this.getXPath().compile(query);
return xPathExpression.evaluate(this.node);
} catch (Exception ex) {
throw new JuRuntimeException("Couldn't evaluate xPath expression: " + query, ex);
}
}
/**
* Evaluates the specified XPath expression and returns a NodeList.
* @param query XPath expression
* @return XPath result as a NodeList
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
private NodeList evaluateNodeSet(String query) throws JuRuntimeException {
try {
XPathExpression xPathExpression = this.getXPath().compile(query);
return (NodeList)xPathExpression.evaluate(this.node, XPathConstants.NODESET);
} catch (Exception ex) {
throw new JuRuntimeException("Couldn't evaluate xPath expression: " + query, ex);
}
}
/**
* Evaluates the specified XPath expression and returns a single String.
* @param query XPath expression
* @return XPath result as String
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public String getSingle(String query) throws JuRuntimeException {
return this.evaluate(query);
}
/**
* Evaluates the specified XPath expression and returns a single Long.
* @param query XPath expression
* @return XPath result as Long
* @throws JuRuntimeException If the XPath cannot be evaluated or if the
* result cannot be converted to a Long
*/
public Long getSingleLong(String query) throws JuRuntimeException {
String value = this.getSingle(query);
if (value == null || value.length() == 0) return null;
try {
return Long.parseLong(value);
} catch (Exception ex) {
throw new JuRuntimeException("Couldn't convert " + value + " to Long", ex);
}
}
/**
* Gets the count of results for the specified queries.
* @param query XPath expression
* @return Number of results
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public int getCount(String query) throws JuRuntimeException {
return this.getNodes(query).length;
}
/**
* Gets whether the specified query either returns nothing or an empty element
* like <a/>
*
* Note that an element is not considered empty though if it contains only empty elements.
* @param query XPath expression
* @return If the expression returns nothing or only empty elements (i.e. an element that doesn't contain
* any attributes nor text. The method also returns true if we find multiple of such elements.
* @throws JuRuntimeException I the XPath cannot be evaluated
*/
public boolean isEmptyElement(String query) throws JuRuntimeException {
for (Node node : this.getNodes(query)) {
if (!StringUtils.isEmpty(node.getTextContent())
|| node.getChildNodes().getLength() > 0
|| node.getAttributes().getLength() > 0) {
return false;
}
}
return true;
}
/**
* Evaluates the specified XPath expression and returns a String array.
* @param query XPath expression
* @return XPath result as String array
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public String[] getArray(String query) throws JuRuntimeException {
try {
XPathExpression xPathExpression = this.getXPath().compile(query);
NodeList list = (NodeList)xPathExpression.evaluate(this.node, XPathConstants.NODESET);
String[] values = new String[list.getLength()];
for (int i = 0; i < list.getLength(); i++) {
Node node = list.item(i);
values[i] = node.getTextContent();
}
return values;
} catch (Exception ex) {
throw new JuRuntimeException("Couldn't evaluate xPath query: " + query);
}
}
/**
* Evaluates the specified XPath expression and returns a Long array.
* @param query XPath expression
* @return XPath result as Long array
* @throws JuRuntimeException If the XPath cannot be evaluated or if a result
* cannot be converted to Long
*/
public Long[] getArrayLong(String query) throws JuRuntimeException {
String[] values = this.getArray(query);
Long[] longValues = new Long[values.length];
for (int i = 0; i < values.length; i++) {
String value = values[i];
if (value == null || value.length() == 0) {
longValues[i] = null;
} else {
try {
longValues[i] = Long.parseLong(value);
} catch (Exception ex) {
throw new JuRuntimeException("Couldn't convert " + value + " to Long", ex);
}
}
}
return longValues;
}
/**
* Evaluates the specified XPath expression and returns a NodeList.
* @param query XPath expression
* @return XPath result as NodeList
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public NodeList getNodeList(String query) throws JuRuntimeException {
return this.evaluateNodeSet(query);
}
/**
* Evaluates the specified XPath expression and returns a list of names of the
* nodes the query matched.
* @param query XPath expression
* @return List of node names
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public List getNodeNames(String query) throws JuRuntimeException {
List nodeNames = new ArrayList<>();
for (Node node : this.getNodes(query)) {
nodeNames.add(node.getNodeName());
}
return nodeNames;
}
/**
* Evaluates the specific XPath expression and returns true if there
* is at least one matching node.
* @param query XPath expression
* @return True if there is at least one matching node
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public boolean exists(String query) throws JuRuntimeException {
return this.evaluateNodeSet(query).getLength() > 0;
}
/**
* Evaluates the specified XPath expression and returns a Node. If the expression
* actually returns more than one Node, only the first one is returned.
* @param query XPath expression
* @return XPath result as Node
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public Node getNode(String query) throws JuRuntimeException {
NodeList list = this.getNodeList(query);
if (list.getLength() == 0) return null;
else return list.item(0);
}
/**
* Evaluates the specified XPath expression and returns an array of Nodes.
* @param query XPath expression
* @return XPath result as an array of Nodes
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public Node[] getNodes(String query) throws JuRuntimeException {
NodeList list = this.getNodeList(query);
Node nodes[] = new Node[list.getLength()];
for (int i = 0; i < list.getLength(); i++) {
nodes[i] = list.item(i);
}
return nodes;
}
/**
* Evaluates the specified XPath expression and returns an array of
* XPathGetters relative to the corresponding result nodes of the query.
* @param query XPath expression
* @return Array of XPathGetters
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public XPathGetter[] getGetters(String query) throws JuRuntimeException {
NodeList list = this.getNodeList(query);
XPathGetter getters[] = new XPathGetter[list.getLength()];
for (int i = 0; i < list.getLength(); i++) {
Node node = list.item(i);
getters[i] = new XPathGetter(node);
}
return getters;
}
/**
* Evaluates the specified XPath expression and returns an
* XPathGetter relative to the corresponding result node of the query.
* @param query XPath expression
* @return XPathGetter
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public XPathGetter getGetter(String query) throws JuRuntimeException {
XPathGetter getters[] = this.getGetters(query);
if (getters.length == 0) return null;
else return getters[0];
}
/**
* Evaluates the specified XPath expression and returns a String array. The array
* contains only distinct values, duplicate values are discarded.
* @param query XPath expression
* @return XPath result as String array containing only distinct values
* @throws JuRuntimeException If the XPath cannot be evaluated
*/
public String[] getDistinctArray(String query) throws JuRuntimeException {
String[] values = this.getArray(query);
List distinctValues = new ArrayList();
for (String value : values) {
if (!distinctValues.contains(value)) distinctValues.add(value);
}
return (String[])distinctValues.toArray(new String[0]);
}
/**
* Evaluates the specified XPath expression and returns a Long array. The array
* contains only distinct values, duplicate values are discarded.
* @param query XPath expression
* @return XPath result as Long array containing only distinct values
* @throws JuRuntimeException If the XPath cannot be evaluated or if a value cannot
* be converted to Long
*/
public Long[] getDistinctArrayLong(String query) throws JuRuntimeException {
String distinctValues[] = this.getDistinctArray(query);
Long distinctValuesLong[] = new Long[distinctValues.length];
for (int i = 0; i < distinctValues.length; i++) {
try {
distinctValuesLong[i] = Long.parseLong(distinctValues[i]);
} catch (Exception ex) {
throw new JuRuntimeException("Couldn't convert " + distinctValues[i] + " to Long", ex);
}
}
return distinctValuesLong;
}
@Override
public String toString() {
return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
.append("node", this.node.getNodeName())
.append("nodeValue", this.node.getNodeValue()).toString();
}
}