com.novartis.opensource.yada.format.ResultSetResultXMLConverter.java Source code

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Here is the source code for com.novartis.opensource.yada.format.ResultSetResultXMLConverter.java

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/**
 * Copyright 2016 Novartis Institutes for BioMedical Research Inc.
 * 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 com.novartis.opensource.yada.format;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

import javax.sql.rowset.RowSetMetaDataImpl;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Element;
import org.w3c.dom.Text;

import com.novartis.opensource.yada.YADAQueryResult;
import com.novartis.opensource.yada.adaptor.JDBCAdaptor;

/**
 * The methods in this class use a {@link java.sql.ResultSet} as source data and return it's content as
 * an {@link org.w3c.dom.DocumentFragment} containing {@code ROW} elements with nested data.
 * 
 * @since 4.0.0
 * @author David Varon
 *
 */
public class ResultSetResultXMLConverter extends AbstractConverter {

    /**
     * Constant equal to: {@value}
     */
    private static final String ROW = "ROW";
    /**
     * Component of Java XML API
     */
    private DocumentBuilderFactory docFactory;
    /**
     * Component of Java XML API
     */
    private DocumentBuilder docBuilder;
    /**
     * Component of Java XML API used to generate the {@link DocumentFragment} to be returned by {@link #convert(Object)}
     * @see #toString()
     */
    private Document doc;

    /**
     * Default construcor, instantiates instance vars.
     * @throws YADAConverterException when the xml api prerequisites can't be instantiated, i.e., when the xml parser can't be configured
     */
    public ResultSetResultXMLConverter() throws YADAConverterException {
        try {
            this.docFactory = DocumentBuilderFactory.newInstance();
            this.docBuilder = this.docFactory.newDocumentBuilder();
            this.doc = this.docBuilder.newDocument();
        } catch (ParserConfigurationException e) {
            throw new YADAConverterException("XML Document creation failed.");
        }

    }

    /**
     * Constructor with {@link YADAQueryResult}
     * @param yqr the container for result processing artifacts
     * @throws YADAConverterException 
     */
    public ResultSetResultXMLConverter(YADAQueryResult yqr) throws YADAConverterException {
        this();
        this.setYADAQueryResult(yqr);
    }

    /**
     * Wraps data in {@code result} in an xml {@link DocumentFragment}
     * @see com.novartis.opensource.yada.format.AbstractConverter#convert(java.lang.Object)
     */
    @Override
    public Object convert(Object result) throws YADAConverterException {
        DocumentFragment rows = null;

        try {
            rows = getXMLRows((ResultSet) result);
        } catch (SQLException e) {
            String msg = "Unable to iterate over ResultSet";
            throw new YADAConverterException(msg, e);
        } catch (JSONException e) {
            String msg = "Unable to read Harmony Map";
            throw new YADAConverterException(msg, e);
        }
        return rows;
    }

    /**
     * Constructs an xml fragment of {@code ROW} elements with the result set data
     * @param rs the result set containing the data to be converted
     * @return a {@link DocumentFragment} containing the result data wrapped in XML
     * @throws SQLException when {@code rs} cannot be iterated or accessed
     */
    private DocumentFragment getXMLRows(ResultSet rs) throws SQLException {
        DocumentFragment rows = this.doc.createDocumentFragment();

        ResultSetMetaData rsmd = rs.getMetaData();
        if (rsmd == null)
            rsmd = new RowSetMetaDataImpl();
        while (rs.next()) {
            Element row = this.doc.createElement(ROW);
            String colValue;
            for (int i = 1; i <= rsmd.getColumnCount(); i++) {
                String colName = rsmd.getColumnName(i);
                if (!colName.toLowerCase().equals(JDBCAdaptor.ROWNUM_ALIAS)) {
                    String col = isHarmonized() && ((JSONObject) this.harmonyMap).has(colName)
                            ? ((JSONObject) this.harmonyMap).getString(colName)
                            : colName;
                    if (null == rs.getString(colName) || NULL.equals(rs.getString(colName))) {
                        colValue = NULL_REPLACEMENT;
                    } else {
                        colValue = rs.getString(colName);
                    }
                    Element column = this.doc.createElement(col);
                    Text value = this.doc.createTextNode(colValue);
                    column.appendChild(value);
                    row.appendChild(column);
                }
            }
            rows.appendChild(row);
        }
        return rows;

    }

}