import java.util.HashMap;
import java.util.Map;
import java.util.Set;


public class JsonUtils {

	/**
	 * String2Json
	 * 
	 * @param str
	 * @return
	 */
	private static String string2Json(String str){
		StringBuilder sb = new StringBuilder();//(str.length()+20);
		sb.append("\"");
		for(int i=0;i<str.length();i++){
			char c = str.charAt(i);
			switch (c) {
			case '\"':
				sb.append("\\\"");
				break;
			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;
			default:
				sb.append(c);
				break;
			}
		}
		
		sb.append("\"");
		return sb.toString();
	}
	
	/**
	 * Number2Json
	 * 
	 * @param number
	 * @return
	 */
	private static String number2Json(Number number){
		return number.toString();
	}
	
	/**
	 * Boolean2Json
	 * 
	 * @param bool
	 * @return
	 */
	private static String boolean2Json(Boolean bool){
		return bool.toString();
	}
	
	/**
	 * Map2Json
	 * 
	 * @param map
	 * @return
	 */
	private static String map2Json(Map<String,Object> map){
		if(map.isEmpty()){
			return "{}";
		}
		StringBuilder sb = new StringBuilder();
		sb.append('{');
		Set<String> keys = map.keySet();
		for(String key:keys){
			Object value = map.get(key);
			sb.append('\"');
			sb.append(key);
			sb.append('\"');
			sb.append(':');
			sb.append(toJson(value));
//			sb.append('}');
			sb.append(',');
		}
		sb.setCharAt(sb.length()-1, '}');
		return sb.toString();
	}
	
	/**
	 * Array2Json
	 * 
	 * @param array
	 * @return
	 */
	private static String array2Json(Object[] array){
		if(array.length==0)
			return "[]";
		StringBuilder sb = new StringBuilder(array.length+20);
		sb.append('[');
		for(Object obj:array){
			sb.append(toJson(obj));
			sb.append(',');
		}
		sb.setCharAt(sb.length()-1, ']');
		return sb.toString();
	}
	
	
	private static String toJson(Object obj){
		if(obj == null)
			return "null";
		if(obj instanceof Number)
			return number2Json((Number) obj);
		if(obj instanceof Boolean)
			return boolean2Json((Boolean) obj);
		if(obj instanceof String)
			return string2Json((String)obj);
		if(obj instanceof Object[])
			return array2Json((Object[]) obj);
		
		return "error:"+obj.toString();
	}

	
	public static void main(String[] args) {
		String str = "abc\t,]";
		System.out.println("test string2Json:"+string2Json(str));
		
		Object[] objArray = new Object[]{"2","3"};
		System.out.println("test arry2Json:"+toJson(objArray));
		
		Map<String,Object> map = new HashMap<String, Object>();
		map.put("a", 1);
		map.put("b", true);
		map.put("c", objArray );
		System.out.println("test map2Json:"+map2Json(map));
		
	}
	
}
 

test string2Json:"abc\t,]"
test arry2Json:["2","3"]
test map2Json:{"b":true,"c":["2","3"],"a":1}