net.ontopia.persistence.query.sql.SQLColumns.java Source code

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Here is the source code for net.ontopia.persistence.query.sql.SQLColumns.java

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/*
 * #!
 * Ontopia Engine
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * 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 net.ontopia.persistence.query.sql;

import java.util.Arrays;
import net.ontopia.persistence.proxy.DefaultFieldHandler;
import net.ontopia.persistence.proxy.FieldHandlerIF;
import org.apache.commons.lang3.StringUtils;

/**
 * INTERNAL: Represents a set of columns from a given table. The
 * columns are grouped for a reason. Columns are often used as join
 * criteria.
 */

public class SQLColumns implements SQLValueIF {

    protected static final Class DEFAULT_VALUE_TYPE = java.lang.String.class;
    protected static final FieldHandlerIF DEFAULT_FIELD_HANDLER = new DefaultFieldHandler(java.sql.Types.VARCHAR);

    protected SQLTable table;
    protected String[] cols;

    protected String alias; // column alias. e.g. A.foo as 'Foo Bar'  

    protected Class vtype;
    protected FieldHandlerIF fhandler;

    public SQLColumns(SQLTable table, String col) {
        this(table, new String[] { col });
    }

    public SQLColumns(SQLTable table, String[] cols) {
        if (table == null)
            throw new IllegalArgumentException("Table cannot be null.");
        if (cols == null || cols.length == 0)
            throw new IllegalArgumentException("List of columns cannot be null or empty.");
        this.table = table;
        this.cols = cols;
    }

    //! public SQLColumns(SQLTable table, String col, String alias) {
    //!   this(table, new String[] { col });
    //!   this.alias = alias;
    //! }
    //! 
    //! public SQLColumns(SQLTable table, String[] cols, String alias) {
    //!   this(table, cols);
    //!   this.alias = alias;
    //! }

    @Override
    public int getType() {
        return COLUMNS;
    }

    @Override
    public int getArity() {
        return cols.length;
    }

    @Override
    public int getValueArity() {
        return 1;
    }

    @Override
    public String getAlias() {
        return alias;
    }

    @Override
    public void setAlias(String alias) {
        this.alias = alias;
    }

    @Override
    public boolean isReference() {
        return false;
    }

    @Override
    public SQLValueIF getReference() {
        throw new UnsupportedOperationException(
                "SQLValueIF is not a reference, so this method should not be called.");
    }

    public SQLTable getTable() {
        return table;
    }

    public String[] getColumns() {
        return cols;
    }

    @Override
    public Class getValueType() {
        return (vtype == null ? DEFAULT_VALUE_TYPE : vtype);
    }

    @Override
    public void setValueType(Class vtype) {
        this.vtype = vtype;
    }

    /**
     * INTERNAL: Returns the field handler for the columns. Default
     * field handler is DefaultFieldHandler with type
     * java.sql.Types.VARCHAR when not specified.
     */
    @Override
    public FieldHandlerIF getFieldHandler() {
        return (fhandler == null ? DEFAULT_FIELD_HANDLER : fhandler);
    }

    @Override
    public void setFieldHandler(FieldHandlerIF fhandler) {
        this.fhandler = fhandler;
    }

    @Override
    public int hashCode() {
        int hashCode = table.hashCode();
        for (int ix = 0; ix < cols.length; ix++) {
            if (cols[ix] != null)
                hashCode = (hashCode + cols[ix].hashCode()) & 0x7FFFFFFF;
        }
        return hashCode;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof SQLColumns) {
            SQLColumns other = (SQLColumns) obj;
            if (table.equals(other.getTable())) {
                if (Arrays.equals(cols, other.getColumns()))
                    return true;
            }
        }
        return false;
    }

    @Override
    public String toString() {
        if (getArity() == 1)
            return getTable().getAlias() + "." + cols[0];
        else {
            return new StringBuilder("columns:").append(getTable().getAlias()).append('(')
                    .append(StringUtils.join(cols, ", ")).append(')').toString();
        }
    }

}