net.mindengine.oculus.frontend.db.jdbc.BeanMappingFactory.java Source code

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Here is the source code for net.mindengine.oculus.frontend.db.jdbc.BeanMappingFactory.java

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/*******************************************************************************
* 2012 Ivan Shubin http://mindengine.net
* 
* This file is part of MindEngine.net Oculus Frontend.
* 
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* 
* This program 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 for more details.
* 
* You should have received a copy of the GNU General Public License
* along with Oculus Frontend.  If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/
package net.mindengine.oculus.frontend.db.jdbc;

import java.io.File;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * This factory is used to execute the sql queries and map the JDBC ResultSet to
 * a simple Java object. Used only in {@link MySimpleJdbcDaoSupport}
 * 
 * @author Ivan Shubin
 * 
 */
public class BeanMappingFactory {
    private Map<String, BeanMapper> beans;
    private File file;

    protected Log logger = LogFactory.getLog(getClass());
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

    /**
     * This method is used for loading the java mapping beans from a specified
     * xml file. Once the {@link #setFile(File)} method was invoked this method
     * wil be invoked as well.
     * 
     * @throws Exception
     */
    public void loadFactory() throws Exception {
        logger.info("Loading db-mapping factory");

        dbf.setNamespaceAware(true);
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse(file);

        beans = new HashMap<String, BeanMapper>();

        NodeList nodeList = d.getElementsByTagName("bean");

        for (int i = 0; i < nodeList.getLength(); i++) {

            Node node = nodeList.item(i);
            loadBean(node);
        }
    }

    public void loadBean(Node node) throws Exception {
        BeanMapper beanMapper = new BeanMapper();
        beanMapper.setClassName(getAttribute(node, "class"));

        Class<?> clazz = Class.forName(beanMapper.getClassName());
        Method[] methods = clazz.getMethods();

        Map<String, FieldMapper> fields = new HashMap<String, FieldMapper>();
        NodeList nodeList = node.getChildNodes();

        for (int i = 0; i < nodeList.getLength(); i++) {

            Node n = nodeList.item(i);
            if ("property".equals(n.getNodeName())) {
                String property = getAttribute(n, "name");
                String column = getAttribute(n, "column");
                String setter = beanMapper.createSetter(property);

                FieldMapper fieldMapper = new FieldMapper();
                fieldMapper.setProperty(property);
                fieldMapper.setColumn(column);

                boolean bFound = false;
                for (int j = 0; j < methods.length && !bFound; j++) {
                    if (methods[j].getName().equals(setter)) {
                        fieldMapper.setMethod(methods[j]);
                        bFound = true;
                    }
                }
                if (!bFound) {
                    throw new Exception("There is no setter method for property '" + property + "'");
                }

                fields.put(fieldMapper.getColumn(), fieldMapper);
            }
        }
        beanMapper.setFields(fields);

        beans.put(beanMapper.getClassName(), beanMapper);
    }

    public String getAttribute(Node node, String attrName) {
        Node attr = node.getAttributes().getNamedItem(attrName);
        if (attr == null)
            assert false : "Attribute " + attrName + " wasn't found";
        return attr.getNodeValue();
    }

    public BeanMapper getBeanMapper(Class<?> clazz) throws Exception {
        if (beans == null) {
            throw new Exception("BeanMappingFactory wasn't initialized");
        }

        String name = clazz.getName();
        BeanMapper bm = beans.get(name);

        if (bm == null)
            throw new Exception("Could find beanMapper for '" + name + "' bean");
        return bm;
    }

    public BeanMappingFactory() {
    }

    public File getFile() {
        return file;
    }

    public void setFile(File file) throws Exception {
        if (beans == null) {
            this.file = file;
            loadFactory();
            this.file = null;
        }
    }
}