org.directwebremoting.datasync.SqlStoreProvider Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
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/*
 * Copyright 2005 Joe Walker
 *
 * 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.directwebremoting.datasync;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.directwebremoting.io.Item;
import org.directwebremoting.io.ItemUpdate;
import org.directwebremoting.io.MatchedItems;
import org.directwebremoting.io.SortCriterion;
import org.directwebremoting.io.StoreChangeListener;
import org.directwebremoting.io.StoreRegion;

/**
 * This file is not supported in any way, and does not function correctly.
 * It might become part of DWR proper at some later date
 * @author Joe Walker [jwalker at sitepen dot com]
 */
class SqlStoreProvider extends AbstractStoreProvider
{
    /**
     *
     */
    private SqlStoreProvider(Class type)
    {
        super(type);
    }

    /**
     * The primary key must be the first column
     */
    private static final String BASE_SQL = "SELECT col1, col2 FROM table";

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#view(org.directwebremoting.io.StoreRegion)
     */
    public MatchedItems view(StoreRegion region)
    {

        // Turn the query into a WHERE clause and an array of parameters
        List params = new ArrayList();
        StringBuilder where = new StringBuilder();
        for (Map.Entry entry : region.getQuery().entrySet())
        {
            if (where.length() == 0)
            {
                where.append(" WHERE ");
            }
            else
            {
                where.append(" AND ");
            }

            String key = entry.getKey();
            where.append(key);
            where.append(" = :");
            where.append(key);

            params.add(entry.getValue());
        }

        // Create an ORDER BY clause
        StringBuilder orderBy = new StringBuilder();
        for (SortCriterion element : region.getSort())
        {
            if (where.length() == 0)
            {
                where.append(" ORDER BY ");
            }
            else
            {
                where.append(", ");
            }

            where.append(element.getAttribute());
            where.append(element.isAscending() ? "ASC" : "DESC");
        }

        // Create a LIMIT x OFFSET y clause
        int start = region.getStart();
        int count = region.getCount();
        String paging;
        if (start == 0)
        {
            if (count == -1)
            {
                // No paging
                paging = "";
            }
            else
            {
                // only as far as 'count'
                paging = " LIMIT " + count;
            }
        }
        else
        {
            if (count == -1)
            {
                throw new UnsupportedOperationException("Can't select a start point without selecting a count");
            }
            // only as far as 'count'
            paging = " LIMIT " + count + " OFFSET " + start;
        }

        String sql = BASE_SQL + where + orderBy + paging;

        Connection con = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        List matchedValues = new ArrayList();

        try
        {
            con = dataSource.getConnection();
            stmt = con.prepareStatement(sql);
            int index = 1;
            for (String element : params)
            {
                stmt.setString(index++, element);
            }

            rs = stmt.executeQuery();
            ResultSetMetaData metaData = rs.getMetaData();
            int columnCount = metaData.getColumnCount();
            // We're going to ignore the zeroth index to be like jdbc
            String[] columnNames = new String[columnCount + 1];
            for (int col = 1; col <= columnCount; col++)
            {
                columnNames[col] = metaData.getColumnName(col);
            }

            Map data = new HashMap();
            while (rs.next())
            {
                String itemId = rs.getString(1);
                for (int col = 2; col <= columnCount; col++)
                {
                    data.put(columnNames[col], rs.getString(col));
                }
                matchedValues.add(new Item(itemId, data));
            }
        }
        catch (SQLException ex)
        {
            log.warn("SQL Failure", ex);
        }
        finally
        {
            if (con != null)
            {
                try
                {
                    con.close();
                }
                catch (SQLException ex2)
                {
                    log.warn("Error closing connection", ex2);
                }
            }

            if (stmt != null)
            {
                try
                {
                    stmt.close();
                }
                catch (SQLException ex2)
                {
                    log.warn("Error closing statement", ex2);
                }
            }

            if (rs != null)
            {
                try
                {
                    rs.close();
                }
                catch (SQLException ex2)
                {
                    log.warn("Error closing resultset", ex2);
                }
            }
        }

        MatchedItems reply = new MatchedItems(matchedValues, -1);
        return reply;
    }

    protected DataSource dataSource;

    public void setDataSource(DataSource dataSource)
    {
        this.dataSource = dataSource;
    }


    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#put(java.lang.String, java.lang.Object)
     */
    public void put(String itemId, T value)
    {
        throw new UnsupportedOperationException("SqlStoreProvider is read only");
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.AbstractStoreProvider#getObject(java.lang.String)
     */
    @Override
    protected T getObject(String itemId)
    {
        // TODO Auto-generated method stub
        return null;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#unsubscribe(org.directwebremoting.io.StoreChangeListener)
     */
    public void unsubscribe(StoreChangeListener listener)
    {
        // TODO Auto-generated method stub

    }

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#update(java.util.List)
     */
    public void update(List changes)
    {
        // TODO Auto-generated method stub

    }

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#viewItem(java.lang.String, org.directwebremoting.io.StoreChangeListener)
     */
    public Item viewItem(String itemId, StoreChangeListener listener)
    {
        // TODO Auto-generated method stub
        return null;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#viewRegion(org.directwebremoting.io.StoreRegion)
     */
    public MatchedItems viewRegion(StoreRegion region)
    {
        // TODO Auto-generated method stub
        return null;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.datasync.StoreProvider#viewRegion(org.directwebremoting.io.StoreRegion, org.directwebremoting.io.StoreChangeListener)
     */
    public MatchedItems viewRegion(StoreRegion region, StoreChangeListener listener)
    {
        // TODO Auto-generated method stub
        return null;
    }

    /**
     * The log stream
     */
    private static final Log log = LogFactory.getLog(SqlStoreProvider.class);
}