public class Json_Controller {
	
	public string json {get;set;}
		
	public Json_Controller() {		
        opportunity[] opps = new opportunity[]{};
		integer start = 0;
		integer pageSize = 10;
		
		if (ApexPages.currentPage().getParameters().get('start') != null && ApexPages.currentPage().getParameters().get('limit') != null) {
			start = integer.valueof(ApexPages.currentPage().getParameters().get('start'));
			pageSize = integer.valueof(ApexPages.currentPage().getParameters().get('limit'));
		}
        
        string jsonRecordsString = '';
        
        integer i = 1;
        integer j = 0;
        
        for (Opportunity o : [Select id, name, stagename, closedate from opportunity order by name limit 1000]) {
			if (j >= start) {
				if (i <= pageSize) {
					jsonRecordsString += '{';
					jsonRecordsString += '"id":' + '"'+o.id+'",';
					jsonRecordsString += '"name":' + '"'+o.name+'",';
					jsonRecordsString += '"stagename":' + '"'+o.stagename+'",';
					jsonRecordsString += '"closedate":' + '"'+o.closedate+'"';
					jsonRecordsString += '},';
					i++;
				}
			}
			opps.add(o);
			j++;
        }
               
		string jsonString = '({"total":"'+opps.size()+'", "results":[' + jsonRecordsString + ']})';
        jsonString = jsonString.replaceAll(',]',']');
        this.json = jsonString;
	}
}