SQLBuilder

package example.jdbc.sqlbuildr;
 
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
 
public class BuilderMain {
    public static void main(String[] args) {
	InsertBuilder builder = new InsertBuilder();
	builder.setTable("employees");
	builder.addColumnAndData("employee_id", new Integer(221));
	builder.addColumnAndData("first_name", "'Shane'");
	builder.addColumnAndData("last_name", "'Grinnell'");
	builder.addColumnAndData("email", "'al@yahoo.com'");
 
	String sql = SQLDirector.buildSQL(builder);
	System.out.println(sql);
    }
}
 
class SQLDirector {
    public static String buildSQL(SQLBuilder builder) {
	StringBuffer buffer = new StringBuffer();
	buffer.append(builder.getCommand());
	buffer.append(builder.getTable());
	buffer.append(builder.getWhat());
	buffer.append(builder.getCriteria());
	return buffer.toString();
    }
}
 
abstract class SQLBuilder {
    /**
     * Gets the command attribute of the SQLBuilder object
     * 
     * @return The command value or what type of Builder this is. This will return a SQL command.
     * @since
     */
    public abstract String getCommand();
 
    /**
     * Gets the table attribute of the SQLBuilder object
     * 
     * @return The table name value
     * @since
     */
    public abstract String getTable();
 
    /**
     * Gets the what value of the SQLBuilder object. This attribute will differ based on what type
     * of object we are using. This could be a list of columns and data.
     * 
     * @return The what value
     * @since
     */
    public abstract String getWhat();
 
    /**
     * Gets the criteria attribute of the SQLBuilder object
     * 
     * @return The criteria value
     * @since
     */
    public abstract String getCriteria();
}
 
class InsertBuilder extends SQLBuilder {
    private String table;
 
    private Map columnsAndData = new HashMap();
 
    private String criteria;
 
    /**
     * Sets the table attribute of the InsertBuilder object
     * 
     * @param table
     *            The new table value
     * @since
     */
    public void setTable(String table) {
	this.table = table;
    }
 
    /**
     * Gets the command attribute of the InsertBuilder object
     * 
     * @return The command value
     * @since
     */
    public String getCommand() {
	return "INSERT INTO ";
    }
 
    /**
     * Gets the table attribute of the InsertBuilder object
     * 
     * @return The table value
     * @since
     */
    public String getTable() {
	return table;
    }
 
    /**
     * Gets the what attribute of the InsertBuilder object
     * 
     * @return The what value
     * @since
     */
    public String getWhat() {
	StringBuffer columns = new StringBuffer();
	StringBuffer values = new StringBuffer();
	StringBuffer what = new StringBuffer();
 
	String columnName = null;
	Iterator iter = columnsAndData.keySet().iterator();
	while (iter.hasNext()) {
	    columnName = (String) iter.next();
	    columns.append(columnName);
	    values.append(columnsAndData.get(columnName));
	    if (iter.hasNext()) {
		columns.append(',');
		values.append(',');
	    }
	}
 
	what.append(" (");
	what.append(columns);
	what.append(") VALUES (");
	what.append(values);
	what.append(") ");
	return what.toString();
    }
 
    /**
     * Gets the criteria attribute of the InsertBuilder object
     * 
     * @return The criteria value
     * @since
     */
    public String getCriteria() {
	return "";
    }
 
    /**
     * Adds a feature to the ColumnAndData attribute of the InsertBuilder object
     * 
     * @param columnName
     *            The feature to be added to the ColumnAndData attribute
     * @param value
     *            The feature to be added to the ColumnAndData attribute
     * @since
     */
    public void addColumnAndData(String columnName, Object value) {
	if (value != null) {
	    columnsAndData.put(columnName, value);
	}
    }
}