sqlbuilder.java

另外一种持久性o/m软件

package org.apache.torque.util;

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * 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.
 */

import java.io.Serializable;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.torque.Torque;
import org.apache.torque.TorqueException;
import org.apache.torque.adapter.DB;
import org.apache.torque.map.ColumnMap;
import org.apache.torque.map.DatabaseMap;
import org.apache.torque.util.Criteria.Criterion;

/**
 * Factored out code that is used to process SQL tables. This code comes
 * from BasePeer and is put here to reduce complexity in the BasePeer class.
 * You should not use the methods here directly!
 *
 * @author <a href="mailto:[e-mail]">Henning P. Schmiedehausen</a>
 * @author <a href="mailto:[e-mail]">Thomas Fischer</a>
 * @version $Id: SQLBuilder.java,v 1.6 2005/07/02 15:22:32 tfischer Exp $
 */
public abstract class SQLBuilder
        implements Serializable
{
    /** Logging */
    protected static Log log = LogFactory.getLog(SQLBuilder.class);

    /**
     * Fully qualify a table name with an optional schema reference
     *
     * @param table The table name to use. If null is passed in, null is returned.
     * @param dbName The name of the database to which this tables belongs.
     *               If null is passed, the default database is used.
     *
     * @return The table name to use inside the SQL statement. If null is passed
     *         into this method, null is returned.
     * @exception TorqueException if an error occurs
     */
    public static final String getFullTableName(final String table, final String dbName)
            throws TorqueException
    {
        if (table != null)
        {
            int dotIndex = table.indexOf(".");

            if (dotIndex == -1) // No schema given
            {
                String targetDBName = (dbName == null) 
                        ? Torque.getDefaultDB()
                        : dbName;
                
                String targetSchema = Torque.getSchema(targetDBName);
                
                // If we have a default schema, fully qualify the
                // table and return.
                if (StringUtils.isNotEmpty(targetSchema))
                {
                    return new StringBuffer()
                            .append(targetSchema)
                            .append(".")
                            .append(table)
                            .toString();
                }
            }
        }

        return table;
    }

    /**
     * Remove a possible schema name from the table name.
     *
     * @param table The table name to use
     *
     * @return The table name with a possible schema name
     *         stripped off
     */
    public static final String getUnqualifiedTableName(final String table)
    {
        if (table != null)
        {
            int dotIndex = table.lastIndexOf("."); // Do we have a dot?

            if (++dotIndex > 0) // Incrementation allows for better test _and_ substring...
            {
                return table.substring(dotIndex);
            }
        }

        return table;
    }

    /**
     * Removes a possible function name or clause from a column name
     *
     * @param name The column name, possibly containing a clause
     *
     * @return The column name
     *
     * @throws TorqueException If the column name was malformed
     */
    private static String removeSQLFunction(final String name)
            throws TorqueException
    {
        // Empty name => return it
        if (StringUtils.isEmpty(name))
        {
            return name;
        }

        final int leftParent = name.lastIndexOf('(');
        final int rightParent = name.indexOf(')');

        // Do we have Parentheses?
        if (leftParent < 0)
        {
            if (rightParent < 0)
            {
                // No left, no right => No function ==> return it
                return name;
            }
        }

        // We have a left parenthesis. Is the right one behind it?
        if (rightParent > leftParent)
        {
            // Yes. Strip off the function, return the column name
            return name.substring(leftParent + 1, rightParent);
        }

        // Bracket mismatch or wrong order ==> Exception
        throwMalformedColumnNameException(
                "removeSQLFunction",
                name);

        return null; // Ugh
    }
    
    /**
     * Removes possible qualifiers (like DISTINCT) from a column name
     *
     * @param name The column name, possibly containing qualifiers
     *
     * @return The column name
     *
     * @throws TorqueException If the column name was malformed
     */
    private static String removeQualifiers(final String name)
            throws TorqueException
    {
        // Empty name => return it
        if (StringUtils.isEmpty(name))
        {
            return name;
        }

        final int spacePos = name.trim().lastIndexOf(' ');

        // Do we have spaces, indicating that qualifiers are used ?
        if (spacePos > 0)
        {
            // Qualifiers are first, tablename is piece after last space
            return name.trim().substring(spacePos + 1);
        }
        
        // no spaces, nothing changed
        return name;
    }
    

    /**
     * Returns a table name from an identifier. Each identifier is to be qualified 
     * as [schema.]table.column. This could also contain FUNCTION([schema.]table.column).
     *
     * @param name The (possible fully qualified) identifier name
     *
     * @return the fully qualified table name
     *
     * @throws TorqueException If the identifier name was malformed
     */
    public static String getTableName(final String name, final String dbName)
            throws TorqueException
    {
        final String testName = removeQualifiers(removeSQLFunction(name));

        if (StringUtils.isEmpty(testName))
        {
            throwMalformedColumnNameException(
                    "getTableName",
                    name);
        }

        // Everything before the last dot is the table name
        int rightDotIndex = testName.lastIndexOf('.');

        if (rightDotIndex < 0)
        {
            if ("*".equals(testName))
            {
                return null;
            }

            throwMalformedColumnNameException(
                    "getTableName",
                    name);
        }

        return getFullTableName(testName.substring(0, rightDotIndex), dbName);
    }
            
            

    /**
     * Returns a set of all tables and possible aliases referenced
     * from a criterion. The resulting Set can be directly used to
     * build a WHERE clause
     *
     * @param crit A Criteria object
     * @param tableCallback A Callback Object
     * @return A Set of tables.
     */
    public static final Set getTableSet(
            final Criteria crit,
            final TableCallback tableCallback)
    {
        HashSet tables = new HashSet();

        // Loop over all the Criterions
        for (Iterator it = crit.keySet().iterator(); it.hasNext(); )
        {
            String key = (String) it.next();
            Criteria.Criterion c = crit.getCriterion(key);
            List tableNames = c.getAllTables();

            // Loop over all Tables referenced in this criterion. 
            for (Iterator it2 = tableNames.iterator(); it2.hasNext(); )
            {
                String name = (String) it2.next();
                String aliasName = crit.getTableForAlias(name);

                // If the tables have an alias, add an "<xxx> AS <yyy> statement"
                if (StringUtils.isNotEmpty(aliasName))
                {
                    String newName = 
                            new StringBuffer(name.length() + aliasName.length() + 4)
                            .append(aliasName)
                            .append(" AS ")
                            .append(name)
                            .toString();
                    name = newName;
                }
                tables.add(name);
            }

            if (tableCallback != null)
            {
                tableCallback.process(tables, key, crit);
            }
        }
        
        return tables;
    }

    /**
     * Builds a Query clause for Updating and deleting
     *
     * @param crit a <code>Criteria</code> value
     * @param params a <code>List</code> value
     * @param qc a <code>QueryCallback</code> value
     * @return a <code>Query</code> value
     * @exception TorqueException if an error occurs
     */
    public static final Query buildQueryClause(final Criteria crit,
            final List params, 
            final QueryCallback qc)
            throws TorqueException
    {
        Query query = new Query();

        final String dbName = crit.getDbName();
        final DB db = Torque.getDB(dbName);
        final DatabaseMap dbMap = Torque.getDatabaseMap(dbName);

        JoinBuilder.processJoins(db, dbMap, crit, query);
        processModifiers(crit, query);
        processSelectColumns(crit, query, dbName);
        processAsColumns(crit, query);
        processCriterions(db, dbMap, dbName, crit, query,  params, qc);
        processGroupBy(crit, query);
        processHaving(crit, query);
        processOrderBy(db, dbMap, crit, query);
        LimitHelper.buildLimit(crit, query);

        if (log.isDebugEnabled())
        {
            log.debug(query.toString());
        }
        return query;
    }


    /**
     * adds the select columns from the criteria to the query
     * @param criteria the criteria from which the select columns are taken
     * @param query the query to which the select columns should be added
     * @throws TorqueException if the select columns can not be processed 
     */
    private static final void processSelectColumns(
            final Criteria criteria,
            final Query query,
            final String dbName)
        throws TorqueException
    {
        UniqueList selectClause = query.getSelectClause();
        UniqueList select = criteria.getSelectColumns();
        
        for (int i = 0; i < select.size(); i++)
        {
            String identifier = (String) select.get(i);
            selectClause.add(identifier);
            addTableToFromClause(getTableName(identifier, dbName), criteria, query); 
        }
    }
    
    /**
     * adds the As-columns from the criteria to the query.
     * @param criteria the criteria from which the As-columns are taken
     * @param query the query to which the As-columns should be added
     */
    private static final void processAsColumns(
            final Criteria criteria,
            final Query query) 
    {
        UniqueList querySelectClause = query.getSelectClause();
        Map criteriaAsColumns = criteria.getAsColumns();
      
        for (Iterator it = criteriaAsColumns.keySet().iterator(); it.hasNext(); )
        {
            String key = (String) it.next();
            querySelectClause.add(
                    new StringBuffer()
                    .append(criteriaAsColumns.get(key))
                    .append(SqlEnum.AS)
                    .append(key)
                    .toString());
        }
    }
    
    /**
     * adds the Modifiers from the criteria to the query
     * @param criteria the criteria from which the Modifiers are taken
     * @param query the query to which the Modifiers should be added
     */
    private static final void processModifiers(
            final Criteria criteria,
            final Query query) 
    {
        UniqueList selectModifiers = query.getSelectModifiers();
        UniqueList modifiers = criteria.getSelectModifiers();
        for (int i = 0; i < modifiers.size(); i++)
        {
            selectModifiers.add(modifiers.get(i));
        }
    }