operatorfactory.java

java实现的全文搜索引擎

/**
 * SimpleFactory Pattern
 */
package cn.edu.nju.software.ruse;

/**
 * @author spring
 *
 */
public class OperatorFactory {

	
	public static Operator createOperator(String operator)
	{
		if(operator.equals("(")) {
			return new Operator_LeftParentheses();
		}else if(operator.equals("NOT")) {
			return new Operator_NOT();
		}else if(operator.equals("OR")) {
			return new Operator_OR();
		}else if(operator.equals("AND")) {
			return new Operator_AND();
		}else if(operator.equals(")")) {
			return new Operator_RightParentheses();
		}else if(operator.equals("#")) {
			return new Operator_END();
		}else if(operator.equals("MODTIME")) {
			return new Operator_ModTime();
		}else if(operator.equals("FILESIZE")) {
			return new Operator_FileSize();
		}else if(operator.equals("FILENAME")) {
			return new Operator_FileName();
		}else if(operator.equals("FILECONTENTS")) {
			return new Operator_FileContents();
		}else if(operator.equals("PROXIMITY")) {
			return new Operator_Proximity();
		}else {
//System.err.println("@Operator The operator is not difined!");
			return null;
		}
	}
}