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The coolest XML library for Java around. Define typesafe views (projections) to xml. Use XPath to read and write XML. Bind XML to Java collections. Requires at least Java6, supports Java8 features and has no further runtime dependencies.

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/**
 *  Copyright 2013 Sven Ewald
 *
 *  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.xmlbeam.io;

import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.DocumentBuilder;

import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import org.xmlbeam.XBProjector;
import org.xmlbeam.evaluation.CanEvaluate;
import org.xmlbeam.evaluation.DefaultXPathEvaluator;
import org.xmlbeam.evaluation.DocumentResolver;
import org.xmlbeam.evaluation.XPathEvaluator;
import org.xmlbeam.exceptions.XBDocumentParsingException;
import org.xmlbeam.exceptions.XBException;
import org.xmlbeam.exceptions.XBIOException;
import org.xmlbeam.util.intern.DocScope;
import org.xmlbeam.util.intern.Scope;

/**
 * @author Sven Ewald
 */
public class StreamInput implements CanEvaluate {

    private final XBProjector projector;
    private final InputStream is;
    private String systemID;

    /**
     * @param xmlProjector
     * @param is
     */
    public StreamInput(final XBProjector xmlProjector, final InputStream is) {
        this.projector = xmlProjector;
        this.is = is;
    }

    /**
     * Create a new projection by parsing the data provided by the input stream.
     *
     * @param projectionInterface
     *            A Java interface to project the data on.
     * @return a new projection instance pointing to the stream content.
     * @throws IOException
     */
    @Scope(DocScope.IO)
    public  T read(final Class projectionInterface) throws IOException {
        Document document = readDocument();
        return projector.projectDOMNode(document, projectionInterface);
    }

    private Document readDocument() throws IOException {
        try {
            DocumentBuilder documentBuilder = projector.config().createDocumentBuilder();
            Document document = systemID == null ? documentBuilder.parse(is) : documentBuilder.parse(is, systemID);
            return document;
        } catch (SAXException e) {
            throw new XBDocumentParsingException(e);
        }
    }

    /**
     * As the system id usually cannot be determined by looking at the stream, this method allows it
     * to be set.
     *
     * @param systemID
     * @return this for convenience.
     */
    @Scope(DocScope.IO)
    public StreamInput setSystemID(final String systemID) {
        this.systemID = systemID;
        return this;
    }

    @Override
    public XPathEvaluator evalXPath(final String xpath) {
        return new DefaultXPathEvaluator(projector, new DocumentResolver() {
            @Override
            public Document resolve(final Class... resourceAwareClass) {
                try {
                    return StreamInput.this.readDocument();
                } catch (IOException e) {
                    throw new XBIOException(e);
                }
            }
        }, xpath);
    }

}