jackson

//msg 是JSON字符串
String msg = "";
ObjectMapper mapper = new ObjectMapper();
Map<String,Object> map = mapper.readValue(msg,Map.class);
//可用于将任何Java值序列化为String的方法。在功能上等同于调用 writeValue(Writer,Object)与StringWriter 和构建字符串，但更有效。
mapper.writeValueAsString(map);

jackson 将String的json文件转换为对象

ObjectMapper mapper = new ObjectMapper();
String json = "{\"dataType\":\"2\",\"newFlag\":\"1\",\"data\":[{\"storeCode\":\"809\",\"businessDay\":\"2019-08-11\",\"orderId\":\"100000412\",\"orderStatus\":2}]}";
OrderInfo orderInfo=mapper.readValue(json,OrderInfo.class);
System.out.println(orderInfo.toString());

实体类

@JsonIgnoreProperties(ignoreUnknown = true)
public class OrderInfo {

    private String newFlag;

    private List<OrderData> data;

    public String getNewFlag() {
        return newFlag;
    }

    public void setNewFlag(String newFlag) {
        this.newFlag = newFlag;
    }



    public List<OrderData> getData() {
        return data;
    }

    public void setData(List<OrderData> data) {
        this.data = data;
    }

    @Override
    public String toString() {
        return "OrderInfo{" +
                "newFlag='" + newFlag + '\'' +
                ", data=" + data +
                '}';
    }

public class OrderData {
    private String storeCode;

    private String businessDay;

    private String orderId;

    private String orderStatus;

    public String getStoreCode() {
        return storeCode;
    }

    public void setStoreCode(String storeCode) {
        this.storeCode = storeCode;
    }

    public String getBusinessDay() {
        return businessDay;
    }

    public void setBusinessDay(String businessDay) {
        this.businessDay = businessDay;
    }

    public String getOrderId() {
        return orderId;
    }

    public void setOrderId(String orderId) {
        this.orderId = orderId;
    }

    public String getOrderStatus() {
        return orderStatus;
    }

    public void setOrderStatus(String orderStatus) {
        this.orderStatus = orderStatus;
    }

    @Override
    public String toString() {
        return "data{" +
                "storeCode='" + storeCode + '\'' +
                ", businessDay='" + businessDay + '\'' +
                ", orderId='" + orderId + '\'' +
                ", orderStatus='" + orderStatus + '\'' +
                '}';
    }
}

jackson String类型转换为对象类型，需要字段名匹配，传入name，变量名命名就是name，get方法必须是getName(); 如果json串中的字段不完全需要映射到实体类中，则可在实体类上加上@JsonIgnoreProperties(ignoreUnknown = true)注解，时jackson在转换时忽略不能映射的字段。

Jackson将复杂String信息解析为map

Map<String, Object> dataMap = null;
try {
    dataMap = mapper.readValue(json, Map.class);
} catch (IOException e) {
    e.printStackTrace();
}
//获取json中的数组，转为List<Map<String,Object>>类型
List<Map<String,Object>> data= (List<Map<String,Object>>) dataMap.get("data");
for (Map<String,Object> map : data){
    //获取数组的属性存入对象
    OrderData.setTransTime(map.get("transTime"));
}