com.emergya.persistenceGeo.dbutils.DatabaseUtilsImpl.java Source code

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Here is the source code for com.emergya.persistenceGeo.dbutils.DatabaseUtilsImpl.java

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/* DatabaseUtilsImpl.java
 * 
 * Copyright (C) 2012
 * 
 * This file is part of project persistence-geo-core
 * 
 * This software 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 2 of the License, or
 * (at your option) any later version.
 * 
 * This software 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 * 
 * Authors:: Juan Luis Rodrguez Ponce (mailto:jlrodriguez@emergya.com)
 */
package com.emergya.persistenceGeo.dbutils;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.sql.DataSource;

import org.apache.commons.collections.iterators.EntrySetMapIterator;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.emergya.persistenceGeo.exceptions.DbUtilsException;

/**
 * @author <a href="mailto:jlrodriguez@emergya.com">jlrodriguez</a>
 * 
 */
@Component
public class DatabaseUtilsImpl implements IDatabaseUtils {

    @Autowired
    private DataSource ds;

    @Override
    public List<String> getTableColumns(String tableName) {
        ResultSet rs = null;
        List<String> result = new ArrayList<String>();
        try {
            Connection con = ds.getConnection();
            DatabaseMetaData md = con.getMetaData();
            rs = md.getColumns(null, null, tableName, null);
            while (rs.next()) {
                result.add(rs.getString("COLUMN_NAME"));
            }
            con.close();

        } catch (SQLException e) {
            throw new DbUtilsException("Error changing column names", e);
        } finally {
            if (rs != null) {
                try {
                    rs.close();

                } catch (SQLException e) {
                    throw new DbUtilsException("Error accessing database", e);
                }
            }
        }
        return result;
    }

    public void changeColumnNames(String tableName, Map<String, String> columns) {
        Set<String> oldColumnNames = columns.keySet();
        Collection<String> newColumnNames = columns.values();
        if (checkClashingColumnNames(oldColumnNames, newColumnNames)) {
            EntrySetMapIterator it = new EntrySetMapIterator(columns);
            while (it.hasNext()) {
                String oldName = (String) it.next();
                String newName = (String) it.getValue();
                try {
                    changeColumnName(tableName, oldName, newName);
                } catch (SQLException e) {
                    throw new DbUtilsException("Error while change column name. [tableName=" + tableName
                            + ", oldColumn= " + oldName + ", newName=" + newName + "]", e);
                }

            }

        } else {
            throw new DbUtilsException("An old column name clash with a new name. [tableName=" + tableName + "]");
        }

    }

    public String getColumnType(String tableName, String columnName) {
        ResultSet rs = null;
        String result = null;
        try {
            Connection con = ds.getConnection();
            DatabaseMetaData md = con.getMetaData();
            rs = md.getColumns(null, null, tableName, columnName);
            int i = 0;
            while (rs.next()) {
                i++;
                result = rs.getString("TYPE_NAME");
                if (i > 1) {
                    throw new DbUtilsException(
                            "Found more than one column when looking for column's type. [tableName=" + tableName
                                    + ", columnName=" + columnName + "]");
                }
            }
            con.close();

        } catch (SQLException e) {
            throw new DbUtilsException("Error getting type of column", e);
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    throw new DbUtilsException("Error accessing database", e);
                }
            }
        }
        return result;
    }

    private void changeColumnName(String tableName, String oldName, String newName) throws SQLException {
        Connection con = ds.getConnection();
        Statement stm = con.createStatement();
        String sql = "ALTER TABLE " + tableName + " RENAME COLUMN " + oldName + " TO " + newName;
        stm.executeUpdate(sql);
        stm.close();
        con.close();

    }

    /**
     * Check if newColumnNames contains any item of oldColumnNames
     * 
     * @param oldColumnNames
     * @param newColumnNames
     * @return
     */
    private boolean checkClashingColumnNames(Collection<String> oldColumnNames, Collection<String> newColumnNames) {
        boolean result = true;

        for (String oldName : oldColumnNames) {

            for (String newName : newColumnNames) {
                if (oldName.toUpperCase().equals(newName.toUpperCase())) {
                    result = false;
                    break;
                }
            }
            if (!result) {
                break;
            }

        }

        return result;
    }

}