一：
response.setContentType("text/html;charset=utf-8");
ObjectMapper mapper=new ObjectMapper();
JsonFactory factory=mapper.getJsonFactory();
JsonGenerator jsonGenerator=factory.createJsonGenerator(response.getOutputStream());
Map map=new HashMap();
map.put("result", "1");
jsonGenerator.writeObject(map);
二：JsonObject json=new JsonObject();
json=JsonObject.fromJsonObject(object);
response.setContentType("text/html;charset=utf-8");
response.getWriter().write(json);
三：
spring MVC 3.X 支持注解，在需要序列化为json输出的类上增加@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
//@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
public class ActTerminalResultParam extends BaseFacadeAmountDepositTradeParam
implements Serializable{
注意：在类上注入此标志时，返回此类时，会返回set属性里的值