java - jackson @JsonIgnore 属性为 null

Question

我想将 json 字符串转换为一个对象。

json 看起来像这样:

{"receive":1413342268310}

该对象如下:

public class PositionBean {  
    private Long id;
    private Date receive;

    public void setReceive (Date receive) {
        this.receive = receive;
    }

    public void setReceive (Long receive) {
        this.receive = new Date (receive);
    }

    public Long getReceive () {
        return receive.getTime ();
    }
}

我必须在其他类中使用所有 set 和 get 方法，因此我无法删除其中一个方法。当我调用时

objectMapper.readValue(str, PositionBean.class);

提示异常，jackon不知道设置了哪个方法，所以我使用@JsonIgnore，但是我发现receive是null。

Answer 1

您可以使用注释@JsonSetter指定应使用哪个方法作为 setter。

示例:

public class PositionBean {  
    private Long id;
    private Date receive;

    public void setReceive (Date receive) {
        this.receive = receive;
    }

    @JsonSetter
    public void setReceive (Long receive) {
        this.receive = new Date (receive);
    }

    public Long getReceive () {
        return receive.getTime ();
    }
}  

当您使用 @JsonIgnore 标记 setter(例如 setXXX)时这意味着属性 XXX 将被忽略。
来自文档:

For example, a "getter" method that would otherwise denote a property (like, say, "getValue" to suggest property "value") to serialize, would be ignored and no such property would be output unless another annotation defines alternative method to use.