package lmc;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
public class JsonUtils {
	public static String classToJson(Object bean){
		StringBuilder json = new StringBuilder();
		json.append("{");
		try{
			Field[]fds = bean.getClass().getDeclaredFields();
			Field fd = null;
			if(fds!=null&&fds.length>0){
				for(int i=0;i<fds.length;i++){
					fd = fds[i];
					fd.setAccessible(true);
					json.append("\""+fd.getName()+"\"");
					json.append(":");
					json.append(JsonUtils.objectToJson(fd.get(bean)));
					json.append(",");
				}
				json.deleteCharAt(json.length()-1);
			}
		}catch(Exception e){
			e.printStackTrace();
		}
		json.append("}");
		return json.toString();
	}
	public static String listToJson(List<?>beans){
		StringBuilder json = new StringBuilder();
		json.append("[");
		if(beans!=null&&beans.size()>0){
			for(Object bean:beans){
				json.append(JsonUtils.objectToJson(bean));
				json.append(",");
			}
			json.setCharAt(json.length()-1,']');
		}
		json.append("]");
		return json.toString();
	}
	private static String objectToJson(Object obj){
		StringBuilder res = new StringBuilder();
		if(obj==null){
			res.append("\"\"");
		}else if(obj instanceof Integer||obj instanceof Boolean||obj instanceof Byte||
			obj instanceof Double||obj instanceof Float||obj instanceof Short||
			obj instanceof Long||obj instanceof BigDecimal||obj instanceof BigInteger){
			res.append("\""+obj.toString()+"\"");
		}else if(obj instanceof String||obj instanceof Character){
			res.append("\""+JsonUtils.filter(obj.toString())+"\"");
		}else if(obj instanceof Date){
			SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
			res.append("\""+sdf.format((Date)obj)+"\"");
		}else{
			res.append("\""+obj.toString()+"\"");
		}
		return res.toString();
	}
	private static String filter(String str){
		if(str==null){
			return "";
		}
		StringBuilder sb = new StringBuilder();
		for(int i=0;i<str.length();i++){
			char ch=str.charAt(i);
		    switch(ch){  
		    	case '"':sb.append("\\\"");break;
		        case '\\':sb.append("\\\\");break;
		        case '\b':sb.append("\\b");break;
		        case '\f':sb.append("\\f");break;
		        case '\n':sb.append("\\n");break;
		        case '\r':sb.append("\\r");break;
		        case '\t':sb.append("\\t");break;
		        case '/':sb.append("\\/");break;
		        default:sb.append(ch);break;
		    }
		}
		return sb.toString();
	}
}