JSONObject 转换为 request 参数

	private String jsonObjToRequestStr(JSONObject json, int length) {

		StringBuilder str;
		Iterator it;
		try {

			str = new StringBuilder();

			if (length > 0) {
				it = json.keys();

				while (it.hasNext()) {
					String name = it.next().toString();
					try {
						str.append(name).append("=").append(json.get(name)).append("&");
					} catch (JSONException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
			return str.substring(0, str.length() - 1).toString();

		} finally {
			json = null;
			str = null;
			it = null;
		}
	}