mongodb $where查询

mongodb中$where查询功能非常强大，不过效率低，这里介绍一下$where的使用方法

db.getCollection('rest.modules.entity.TestCase').find({$where:
    function () { 
        var result=true;
        var selectTarger='ffffe10183c3e1ff';
        var temp = this.fingerCode;
        var different = 0;
        for(var i=0;i<16;i++){
            if (selectTarger.charAt(i)!=temp.charAt(i)){
                different++;
            }
        }
        if (different==0){
            result = true;
        }else if (different <= 5){
            result = true;
        }else{
            result=false;
        }
        return result;
     }
  }).limit(10);
  

用java mongo driver调用

BasicDBObject totalQuery=new BasicDBObject();
				
				StringBuilder sb=new StringBuilder();					
				sb.append("function () { var result=true;");
				sb.append("var selectTarger='"+fingerCode+"';");
				sb.append("var temp =     this."+whereT.getFingerCodeField()+";");
				sb.append("var different = 0;");
				sb.append("for(var i=0;i<16;i++){");
				sb.append("if (selectTarger.charAt(i)!=temp.charAt(i)){");
				sb.append("different++;");
				sb.append("}");
				sb.append("}");
				sb.append("if (different==0){");
				sb.append("result = true;");
				sb.append("}else if (different <= 5){");
				sb.append("result = true;");
				sb.append("}else{");
				sb.append("result=false;");
				sb.append("}return result;}");
				

			
				
				totalQuery.append(QueryOperators.WHERE, sb.toString());
				
				
				
			    FindIterable<Document> fiList = collection.find(totalQuery).limit(10);