hxttdbfdialect.java

hibernate连接access数据库,以及一些其他的hibernate介绍

package com.hxtt.support.hibernate;

import java.sql.Types;

/**
 * An SQL dialect for HXTT DBF.
 */
public class HxttDbfDialect extends HxttDialect {

	public HxttDbfDialect() {
		super();
        //complete map
        registerColumnType( Types.BIT, "boolean" );
        registerColumnType(Types.CHAR, "char(l)");
        registerColumnType( Types.VARCHAR, "varchar($l)" );
        //registerColumnType( Types.VARCHAR,255, "varchar($l)" );
        registerColumnType( Types.LONGVARCHAR,  "longvarchar");
        registerColumnType( Types.NUMERIC, "numeric($p,$s)" );
        registerColumnType( Types.BOOLEAN, "boolean" );
       	registerColumnType( Types.BIGINT, "numeric(19,0)" );  // HXTT DBF DON'T SUPPORT BIGINT
        registerColumnType( Types.SMALLINT, "smallint");//"numeric(5,0)" ); // HXTT DBF DON'T SUPPORT SMALLINT
        registerColumnType( Types.TINYINT, "tinyint");//"numeric(3,0)" );   // HXTT DBF DON'T SUPPORT TINYINT
	registerColumnType( Types.INTEGER, "integer" );
	registerColumnType( Types.FLOAT, "float" );           // HXTT DBF DON'T SUPPORT FLOAT ,it will be a double type
	registerColumnType( Types.DOUBLE, "double" );
        registerColumnType( Types.BINARY, 255, "binary" );
 	registerColumnType( Types.VARBINARY, 255, "varbinary" );
        registerColumnType( Types.LONGVARBINARY, "longvarbinary");

	registerColumnType( Types.DATE, "date" );
        // registerColumnType( Types.TIME, "time" );   //  HXTT DBF DON'T SUPPORT TIME
	registerColumnType( Types.TIMESTAMP, "timestamp" );
        registerColumnType( Types.BLOB, "blob" ); // BLOB COLUMN WILL CHANGE TO  JAVA_OBJECT TYPE COLUMN
        registerColumnType( Types.CLOB, "clob" ); // CLOB COLUMN WILL CHANGE TO  LONGVARCHAR TYPE COLUMN
        registerColumnType( Types.OTHER, "currency" );
        registerColumnType( Types.OTHER, "graphics" );
        registerColumnType( Types.JAVA_OBJECT, "java_object" );
    }




    /**
     * Apply s limit clause to the query.
     * <p/>
     * Typically dialects utilize {@link #supportsVariableLimit() variable}
     * limit caluses when they support limits.  Thus, when building the
     * select command we do not actually need to know the limit or the offest
     * since we will just be using placeholders.
     * <p/>
     * Here we do still pass along whether or not an offset was specified
     * so that dialects not supporting offsets can generate proper exceptions.
     * In general, dialects will override one or the other of this method and
     * {@link #getLimitString(String, int, int)}.
     *
     * @param query The query to which to apply the limit.
     * @param hasOffset Is the query requesting an offset?
     * @return the modified SQL
     */
    public String getLimitString(String sql, boolean hasOffset) {

        sql = sql.trim();
        boolean isForUpdate = false;
        if ( sql.toLowerCase().endsWith(" for update") ) {
            sql = sql.substring( 0, sql.length()-11 );
            isForUpdate = true;
        }

        StringBuffer pagingSelect = new StringBuffer( sql.length()+100 );
        if (hasOffset) {
            pagingSelect.append("select * from ( select row_.*, RECNO() rownum_ from ( ");
        }
        else {
            pagingSelect.append("select * from ( ");
        }
        pagingSelect.append(sql);
        if (hasOffset) {
            pagingSelect.append(" ) row_ where RECNO() <= ?) where rownum_ > ?");
        }
        else {
            pagingSelect.append(" ) where RECNO() <= ?");
        }

        if (isForUpdate) pagingSelect.append(" for update");

        return pagingSelect.toString();
    }





}