public String addBecomeinvalid(@Context HttpServletRequest request,HashMap<String, Object> data) {
		JSONObject obj = new JSONObject();
		SqlSession session = Dbhelper.getInstance().getSession();
		try {
			Businesstravel businesstravel = new Businesstravel();
			
			BusinesstravelMapper mapper = session.getMapper(BusinesstravelMapper.class);
			TripMapper tripMapper = session.getMapper(TripMapper.class);
			BoAccessoryMapper acmapper = session.getMapper(BoAccessoryMapper.class);
			
			if(data!=null) {
					Gson gson = new  GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
//					出差表
					businesstravel = gson.fromJson(gson.toJson(data), Businesstravel.class); 
					if(businesstravel.getId()!=null) {
						 mapper.updateByPrimaryKey(businesstravel);
					}else {
						businesstravel.setCreatetime(new Date());
						mapper.insert(businesstravel);
					}
//					行程表
					
					List<Trip> tripList = businesstravel.getTripList();
//					tripList= gson.fromJson(String.valueOf(data.get("trip")), new TypeToken<List<Trip>>() {}.getType());
					for(Trip trip:tripList) {
						if(trip.getId()!=null) {
							 tripMapper.updateByPrimaryKey(trip);
						}else {
							trip.setBusinesstId(businesstravel.getId());
							tripMapper.insert(trip);
						}
//						附件表
						List<BoAccessory> BoAccessoryList = trip.getBoAccessory();
						for(BoAccessory boAccessory:BoAccessoryList) {
							if(boAccessory.getId()!=null) {
								 acmapper.updateByPrimaryKey(boAccessory);
							}else {
								boAccessory.setBusiid(trip.getId().toString());
								acmapper.insert(boAccessory);
							}
						}
					}

			}
			session.commit();
			
			obj.put("result", "success");
		}catch (Exception e) {
			session.rollback();
			e.printStackTrace();
			obj.put("result", "error");
			obj.put("data", e.getMessage());
		}finally {
			session.close();
		}
		
		return obj.toJSONString();
	}
	

这个是一个实体类

Gson gson = new  GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();

businesstravel = gson.fromJson(gson.toJson(data), Businesstravel.class); 

gson.fromJson(String.valueOf(data.get(“trip”)), new TypeToken<List>() {}.getType());

这个是list

1.新建实体类（其中字段信息根据自己要存储的内容添加）：

public class JsonCityIdBean {
    private String stratCityId;
    private String transferCityId;
    private String endCityId;

    public String getStratCityId() {
        return stratCityId;
    }

    public void setStratCityId(String stratCityId) {
        this.stratCityId = stratCityId;
    }

    public String getTransferCityId() {
        return transferCityId;
    }

    public void setTransferCityId(String transferCityId) {
        this.transferCityId = transferCityId;
    }

    public String getEndCityId() {
        return endCityId;
    }

    public void setEndCityId(String endCityId) {
        this.endCityId = endCityId;
    }
}

2.新建list集合，并将要转换的值添加到list集合中：

  private List<JsonCityIdBean> jsonList=new ArrayList<>();  //新建的list集合
         //实例化实体类，向实体类中添加自己需要转换的值
        JsonCityIdBean jsonCityIdBean=new JsonCityIdBean();
        jsonCityIdBean.setStratCityId(String.valueOf(startCityId));
        jsonCityIdBean.setTransferCityId(String.valueOf(transferCityId));
        jsonCityIdBean.setEndCityId(String.valueOf(endCityId));
        
        //将添加完信息的实体类对象赋给list集合
        jsonList.add(jsonCityIdBean);
        
        //通过Gson将list集合转换为json格式字符串
        Gson gson=new Gson();
        String string=gson.toJson(jsonList);
        UtilLog.e("#:"+string);
        
输出结果：TAG: #:[{"endCityId":"420100","stratCityId":"370100","transferCityId":"350100"}]