mckoicasefragment.java

来自「用Java实现的23个常用设计模式源代码」· Java 代码 · 共 61 行

//$Id: MckoiCaseFragment.java,v 1.1.2.4 2003/11/27 16:10:00 oneovthafew Exp $
package net.sf.hibernate.sql;

import java.util.Iterator;
import java.util.Map;
import net.sf.hibernate.util.StringHelper;
import org.apache.commons.collections.SequencedHashMap;

/**
 * A Mckoi IF function.
 * <br>
 * <code>if(..., ..., ...) as ...</code>
 * <br>
 * @author Gavin King
 */
public class MckoiCaseFragment extends CaseFragment {

	private String returnColumnName;

	private Map cases = new SequencedHashMap();

	public CaseFragment setReturnColumnName(String returnColumnName) {
		this.returnColumnName = returnColumnName;
		return this;
	}

	public CaseFragment setReturnColumnName(String returnColumnName, String suffix) {
		return setReturnColumnName( new Alias(suffix).toAliasString(returnColumnName) );
	}

	public CaseFragment addWhenColumnNotNull(String alias, String columnName, String value) {
		cases.put( StringHelper.qualify(alias, columnName) + " is not null", value );
		return this;
	}

	public String toFragmentString() {
		StringBuffer buf = new StringBuffer( cases.size() * 15 + 10 );

		StringBuffer buf2= new StringBuffer( cases.size() );
		Iterator iter = cases.entrySet().iterator();
		while ( iter.hasNext() ) {
			Map.Entry me = (Map.Entry) iter.next();
			buf.append(" if(")
				.append( me.getKey() )
				.append(", ")
				.append( me.getValue() )
				.append(", ");
			buf2.append(")");
		}
		buf.append("null");
		buf.append(buf2);
		if (returnColumnName!=null) {
			buf.append(" as ")
				.append(returnColumnName);
		}
		
		return buf.toString();
	}
}