如何使用jackson在java中解包和序列化java地图？

我有一颗这样的豆子

class Foo {
    private Map<String, Data> dataMap;
    private String fooFieldOne;
    private String fooFieldTwo;
}

class Data {
    private fieldOne;
    private fieldTwo;
}

我想像这样序列化为 Json

{
    "key1": {
        "fieldOne": "some value",
        "fieldTwo": "some value"
    },
    "key2": {
        "fieldOne": "some other value",
        "fieldTwo": "some other value"
    },
    "fooFieldOne":"valueone", 
    "fooFieldTwo":"valuetwo" 
}

但我得到的结果是这样的

{
    "dataMap": {
        "key1": {
            "fieldOne": "some value",
            "fieldTwo": "some value"
        },
        "key2": {
            "fieldOne": "some other value",
            "fieldTwo": "some other value"
        }
    },
    "fooFieldOne":"valueone", 
    "fooFieldTwo":"valuetwo" 
}

如何忽略上面json中的dataMap层？我为此使用 java jackson 库。

我尝试过的代码是

ObjectMapper mapper = new ObjectMapper();
mapper.writeValueAsString(myFOOObject)

你可以为dataMap并序列化dataMap而不是整个Foo实例。

mapper.writeValueAsString(myFOOObject.getDataMap());

另一种方法是使用@JsonUnwrapped注解。此注释在 Jackson 1.9+ 中可用。

http://jackson.codehaus.org/1.9.9/javadoc/org/codehaus/jackson/annotate/JsonUnwrapped.html http://jackson.codehaus.org/1.9.9/javadoc/org/codehaus/jackson/annotate/JsonUnwrapped.html

使用此注释的缺点是无法使用地图，如回答你的另一个问题 https://stackoverflow.com/questions/18043587/why-im-not-able-to-unwrapp-and-serialize-java-map-using-jackson-java-library