private void getToken(){
		//óʼֵ
		this.tokenType=NONE_TOKEN;
		this.token="";
		
		//ʽǷָ±ַ
		//ʽѾõǰ־ΪEOE
		if(this.expIndex==this.exp.length()){
			this.token=EOE;
			return;
		}
		//ʽĿհ׷
		while(this.expIndex<this.exp.length()
				&&Character.isWhitespace(this.exp.charAt(this.expIndex))){
			this.expIndex++;
		}
		//ٴμʽǷ
		if(this.expIndex==this.exp.length()){
			this.token=EOE;
			return;
		}
		char currentChar=this.exp.charAt(expIndex);
		//ȡýǰַָָ
		//ǰַһָΪһָ
		//ǰǺͱ͸ֵָ
		if(isDelim(currentChar)){
			this.token+=currentChar;
			this.expIndex++;
			this.tokenType=DELIMITER_TOKEN;
		}else if(Character.isLetter(currentChar)){
			//ǰַһĸΪһ
			//ʽָƣֱһַָ֮Ǳɲ
			//while(!isDelim(currentChar)){
			while(!isFunctionOver()){
				this.token+=currentChar;
				this.expIndex++;
				if(this.expIndex>=this.exp.length()){
					break;
				}else{
					currentChar=this.exp.charAt(this.expIndex);
				}
			}
			//System.out.println("finction:"+token);
			this.tokenType=VARIABLE_TOKEN;		//ñΪ/
		}else if(Character.isDigit(currentChar)){
			//ǰַһ֣ΪǰǵΪ
			//ָƣֱһַָ֮Ǹַɲ
			while(!isDelim(currentChar)){
				this.token+=currentChar;
				this.expIndex++;
				if(this.expIndex>=this.exp.length()){
					break;
				}else{
					currentChar=this.exp.charAt(this.expIndex);
				}
			}
			this.tokenType=NUMBER_TOKEN;
		}else{
			//޷ʶַΪʽ
			this.token=EOE;
			return;
		}
	}