java/jackson - 不要序列化包装类

Question

当使用 Jackson 库序列化一个字符串列表时，它正确地提供了一个 JSON 字符串数组:

<mapper>.writeValue(System.out, Arrays.asList("a", "b", "c"));

[ "a", "b", "c" ]

但是，字符串被我们代码中的一个类包装/封闭:

public static class StringWrapper {
    protected final String s;

    public String getS() {
        return s;
    }

    public StringWrapper(final String s) {
        this.s = s;
    }
}

当序列化“字符串包装器”列表时，我希望得到与上面相同的输出。现在我得到:

<mapper>.writeValue(System.out, Arrays.asList(new StringWrapper("a"), new StringWrapper("b"), new StringWrapper("c")));

[ {
  "s" : "a"
}, {
  "s" : "b"
}, {
  "s" : "c"
} ]

最方便的方法是什么？如果可能，反序列化也应该有效。

Answer 1

您可以在单个 getter 上使用 @JsonValue

@JsonValue
public String getS() {
    return s;
}

来自javadoc，

Marker annotation similar to javax.xml.bind.annotation.XmlValue that indicates that results of the annotated "getter" method (which means signature must be that of getters; non-void return type, no args) is to be used as the single value to serialize for the instance. Usually value will be of a simple scalar type (String or Number), but it can be any serializable type (Collection, Map or Bean).