|
|
The XPath.java Java example source code
/*
* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.xml.xpath;
import org.xml.sax.InputSource;
import javax.xml.namespace.QName;
import javax.xml.namespace.NamespaceContext;
/**
* <p>XPath provides access to the XPath evaluation environment and expressions.
*
* <a name="XPath-evaluation"/>
* <table border="1" cellpadding="2">
* <thead>
* <tr>
* <th colspan="2">Evaluation of XPath Expressions.
* </tr>
* </thead>
* <tbody>
* <tr>
* <td>context |
* <td>
* If a request is made to evaluate the expression in the absence
* of a context item, an empty document node will be used for the context.
* For the purposes of evaluating XPath expressions, a DocumentFragment
* is treated like a Document node.
* </td>
* </tr>
* <tr>
* <td>variables
* <td>
* If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}
* set with {@link #setXPathVariableResolver(XPathVariableResolver resolver)}.
* An {@link XPathExpressionException} is raised if the variable resolver is undefined or
* the resolver returns <code>null for the variable.
* The value of a variable must be immutable through the course of any single evaluation.</p>
* </td>
* </tr>
* <tr>
* <td>functions
* <td>
* If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}
* set with {@link #setXPathFunctionResolver(XPathFunctionResolver resolver)}.
* An {@link XPathExpressionException} is raised if the function resolver is undefined or
* the function resolver returns <code>null for the function.
* </td>
* </tr>
* <tr>
* <td>QNames
* <td>
* QNames in the expression are resolved against the XPath namespace context
* set with {@link #setNamespaceContext(NamespaceContext nsContext)}.
* </td>
* </tr>
* <tr>
* <td>result
* <td>
* This result of evaluating an expression is converted to an instance of the desired return type.
* Valid return types are defined in {@link XPathConstants}.
* Conversion to the return type follows XPath conversion rules.</p>
* </td>
* </tr>
* </table>
*
* <p>An XPath object is not thread-safe and not reentrant.
* In other words, it is the application's responsibility to make
* sure that one {@link XPath} object is not used from
* more than one thread at any given time, and while the <code>evaluate
* method is invoked, applications may not recursively call
* the <code>evaluate method.
* <p>
*
* @author <a href="Norman.Walsh@Sun.com">Norman Walsh
* @author <a href="Jeff.Suttor@Sun.com">Jeff Suttor
* @see <a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version 1.0
* @since 1.5
*/
public interface XPath {
/**
* <p>Reset this XPath to its original configuration.
*
* <p>XPath is reset to the same state as when it was created with
* {@link XPathFactory#newXPath()}.
* <code>reset() is designed to allow the reuse of existing XPaths
* thus saving resources associated with the creation of new <code>XPaths.
*
* <p>The reset XPath is not guaranteed to have the same {@link XPathFunctionResolver}, {@link XPathVariableResolver}
* or {@link NamespaceContext} <code>Objects, e.g. {@link Object#equals(Object obj)}.
* It is guaranteed to have a functionally equal <code>XPathFunctionResolver, XPathVariableResolver
* and <code>NamespaceContext.
*/
public void reset();
/**
* <p>Establish a variable resolver.
*
* <p>A NullPointerException is thrown if resolver is null.
*
* @param resolver Variable resolver.
*
* @throws NullPointerException If <code>resolver is null.
*/
public void setXPathVariableResolver(XPathVariableResolver resolver);
/**
* <p>Return the current variable resolver.
*
* <p>null is returned in no variable resolver is in effect.
*
* @return Current variable resolver.
*/
public XPathVariableResolver getXPathVariableResolver();
/**
* <p>Establish a function resolver.
*
* <p>A NullPointerException is thrown if resolver is null.
*
* @param resolver XPath function resolver.
*
* @throws NullPointerException If <code>resolver is null.
*/
public void setXPathFunctionResolver(XPathFunctionResolver resolver);
/**
* <p>Return the current function resolver.
*
* <p>null is returned in no function resolver is in effect.
*
* @return Current function resolver.
*/
public XPathFunctionResolver getXPathFunctionResolver();
/**
* <p>Establish a namespace context.
*
* <p>A NullPointerException is thrown if nsContext is null.
*
* @param nsContext Namespace context to use.
*
* @throws NullPointerException If <code>nsContext is null.
*/
public void setNamespaceContext(NamespaceContext nsContext);
/**
* <p>Return the current namespace context.
*
* <p>null is returned in no namespace context is in effect.
*
* @return Current Namespace context.
*/
public NamespaceContext getNamespaceContext();
/**
* <p>Compile an XPath expression for later evaluation.
*
* <p>If expression contains any {@link XPathFunction}s,
* they must be available via the {@link XPathFunctionResolver}.
* An {@link XPathExpressionException} will be thrown if the
* <code>XPathFunction
* cannot be resovled with the <code>XPathFunctionResolver.
*
* <p>If expression contains any variables, the
* {@link XPathVariableResolver} in effect
* <strong>at compile time will be used to resolve them.
*
* <p>If expression is null, a NullPointerException is thrown.
*
* @param expression The XPath expression.
*
* @return Compiled XPath expression.
* @throws XPathExpressionException If <code>expression cannot be compiled.
* @throws NullPointerException If <code>expression is null.
*/
public XPathExpression compile(String expression)
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the specified context and return the result as the specified type.
*
* <p>See Evaluation of XPath Expressions for context item evaluation,
* variable, function and <code>QName resolution and return type conversion.
*
* <p>If returnType is not one of the types defined in {@link XPathConstants} (
* {@link XPathConstants#NUMBER NUMBER},
* {@link XPathConstants#STRING STRING},
* {@link XPathConstants#BOOLEAN BOOLEAN},
* {@link XPathConstants#NODE NODE} or
* {@link XPathConstants#NODESET NODESET})
* then an <code>IllegalArgumentException is thrown.
*
* <p>If a null value is provided for
* <code>item, an empty document will be used for the
* context.
* If <code>expression or returnType is null, then a
* <code>NullPointerException is thrown.
*
* @param expression The XPath expression.
* @param item The starting context (a node, for example).
* @param returnType The desired return type.
*
* @return Result of evaluating an XPath expression as an <code>Object of returnType.
*
* @throws XPathExpressionException If <code>expression cannot be evaluated.
* @throws IllegalArgumentException If <code>returnType is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If <code>expression or returnType is null.
*/
public Object evaluate(String expression, Object item, QName returnType)
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the specified context and return the result as a String.
*
* <p>This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a returnType of
* {@link XPathConstants#STRING}.</p>
*
* <p>See Evaluation of XPath Expressions for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If a null value is provided for
* <code>item, an empty document will be used for the
* context.
* If <code>expression is null, then a NullPointerException is thrown.
*
* @param expression The XPath expression.
* @param item The starting context (a node, for example).
*
* @return The <code>String that is the result of evaluating the expression and
* converting the result to a <code>String.
*
* @throws XPathExpressionException If <code>expression cannot be evaluated.
* @throws NullPointerException If <code>expression is null.
*/
public String evaluate(String expression, Object item)
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the context of the specified InputSource
* and return the result as the specified type.</p>
*
* <p>This method builds a data model for the {@link InputSource} and calls
* {@link #evaluate(String expression, Object item, QName returnType)} on the resulting document object.</p>
*
* <p>See Evaluation of XPath Expressions for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If returnType is not one of the types defined in {@link XPathConstants},
* then an <code>IllegalArgumentException is thrown.
*
* <p>If expression, source or returnType is null,
* then a <code>NullPointerException is thrown.
*
* @param expression The XPath expression.
* @param source The input source of the document to evaluate over.
* @param returnType The desired return type.
*
* @return The <code>Object that encapsulates the result of evaluating the expression.
*
* @throws XPathExpressionException If expression cannot be evaluated.
* @throws IllegalArgumentException If <code>returnType is not one of the types defined in {@link XPathConstants}.
* @throws NullPointerException If <code>expression, source or returnType
* is <code>null.
*/
public Object evaluate(
String expression,
InputSource source,
QName returnType)
throws XPathExpressionException;
/**
* <p>Evaluate an XPath expression in the context of the specified InputSource
* and return the result as a <code>String.
*
* <p>This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
* <code>returnType of {@link XPathConstants#STRING}.
*
* <p>See Evaluation of XPath Expressions for context item evaluation,
* variable, function and QName resolution and return type conversion.</p>
*
* <p>If expression or source is null,
* then a <code>NullPointerException is thrown.
*
* @param expression The XPath expression.
* @param source The <code>InputSource of the document to evaluate over.
*
* @return The <code>String that is the result of evaluating the expression and
* converting the result to a <code>String.
*
* @throws XPathExpressionException If expression cannot be evaluated.
* @throws NullPointerException If <code>expression or source is null.
*/
public String evaluate(String expression, InputSource source)
throws XPathExpressionException;
}
Other Java examples (source code examples)
Here is a short list of links related to this Java XPath.java source code file:
The search page
Other Java source code examples at this package level
Click here to learn more about this project
