杰克逊为什么还要将瞬态成员序列化？ [英] Why jackson is serializing transient member also?

问题描述

我使用Jackson 2.1.4将POJO序列化为JSON，但我想忽略序列化的特定字段。我使用了瞬态，但它仍在序列化该元素。

I am serializing a POJO into JSON using Jackson 2.1.4 but I want to ignore a particular field from getting serialized. I used transient but still it is serializing that element.

public class TestElement {

    int x;

    private transient String y;

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public String getY() {
        return y;
    }

    public void setY(String y) {
        this.y = y;
    }
}

我序列化如下：

public static void main(String[] args) throws JsonProcessingException {
    TestElement testElement = new TestElement();
    testElement.setX(10);
    testElement.setY("adasd");
    ObjectMapper om = new ObjectMapper();
    String serialized = om.writeValueAsString(testElement);
    System.err.println(serialized);
}

请不要建议 @JsonIgnore 因为我不想将我的模型与杰克逊特定的注释联系起来。可以仅使用瞬态完成吗？ objectmapper上有可用于可见性设置的API吗？

Please don't suggest @JsonIgnore as I don't want to tie my model to jackson specific annotations. Can it be done using transient only? Is there any API on objectmapper for visibility settings?

推荐答案

Jackson序列化瞬态的原因 member是因为getter用于确定序列化的内容，而不是成员本身 - 并且因为 y 有一个公共getter，它会被序列化。
如果你想更改默认值并让Jackson使用字段 - 只需：

The reason Jackson serializes the transient member is because the getters are used to determine what to serialize, not the member itself - and since y has a public getter, that gets serialized. If you want to change that default and have Jackson use fields - simply do:

om.setVisibilityChecker(
om.getSerializationConfig().
getDefaultVisibilityChecker().
withFieldVisibility(JsonAutoDetect.Visibility.ANY).
withGetterVisibility(JsonAutoDetect.Visibility.NONE));

忽略序列化属性的另一种方法是直接在类上执行：

Another way to ignore a property on serialization is to do it directly on the class:

@JsonIgnoreProperties(value = { "y" })
public class TestElement {
...

另一种方式直接在现场：

And another way is directly on the field:

public class TestElement {

    @JsonIgnore
    private String y;
...

希望这会有所帮助。

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