Question

我需要映射以下JSON：

(ListBox.Items[2] as DataItem).SelectedIndex = 1;

看起来像这样： JSON

在我不需要＆＃34;覆盖＆＃34;字段（我的域类只有ID和名称）。现在，当我需要它时，我也遇到了问题。

这是我用来将我的JSON映射为字符串的代码行（就像我说的，如果我只坚持id和name字段，它可以正常工作）。

[{"id":7346,"name":"The Legend of Zelda: Breath of the Wild","cover":{"url":"//images.igdb.com/igdb/image/upload/t_thumb/jk9el4ksl4c7qwaex2y5.jpg","cloudinary_id":"jk9el4ksl4c7qwaex2y5","width":2709,"height":3816}},{"id":2909,"name":"The Legend of Zelda: A Link Between Worlds","cover":{"url":"//images.igdb.com/igdb/image/upload/t_thumb/r9ezsk5yhljc83dfjeqc.jpg","cloudinary_id":"r9ezsk5yhljc83dfjeqc","width":406,"height":362}}]

我的 Suggestion.java 类：

List<Suggestion> suggestions = mapper.readValue(requestString, new TypeReference<List<Suggestion>>(){});

我的 Cover.java 类：

public class Suggestion {

private long id;
private String name;
private Cover cover;

public Suggestion(){
}

public Suggestion(long id, String name, Cover cover) {
    this.id = id;
    this.name = name;
    this.cover = cover;
}

public long getId() {
    return id;
}

public String getName() {
    return name;
}

public Cover getCover() {
    return cover;
}

}

我已经使用http://www.jsonschema2pojo.org/来获得这个想法（其他属性不是必需的）并且我不确定它为什么不再起作用。

那么这可能是什么问题？

Answer 1

让我们来看看导致问题的原因。如果您使用已提供的类运行代码，您将获得以下异常：

线程中的异常＆＃34; main＆＃34; com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException：无法识别的字段＆＃34; cloudinary_id＆＃34;

您的示例中的JSON如下：

[
  {
    "id": 7346,
    "name": "The Legend of Zelda: Breath of the Wild",
    "cover": {
      "url": "//images.igdb.com/igdb/image/upload/t_thumb/jk9el4ksl4c7qwaex2y5.jpg",
      "cloudinary_id": "jk9el4ksl4c7qwaex2y5",
      "width": 2709,
      "height": 3816
    }
  },
  {
    "id": 2909,
    "name": "The Legend of Zelda: A Link Between Worlds",
    "cover": {
      "url": "//images.igdb.com/igdb/image/upload/t_thumb/r9ezsk5yhljc83dfjeqc.jpg",
      "cloudinary_id": "r9ezsk5yhljc83dfjeqc",
      "width": 406,
      "height": 362
    }
  }
]

您错过了使用@JsonProperty注释将JSON指定给属性字段映射。将您的Cover课程更新为：

public class Cover {

    private String url;
    @JsonProperty("cloudinary_id")
    private String cloudinaryId;
    private Integer width;
    private Integer height;

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getCloudinaryId() {
        return cloudinaryId;
    }

    public void setCloudinaryId(String cloudinaryId) {
        this.cloudinaryId = cloudinaryId;
    }

    public Integer getWidth() {
        return width;
    }

    public void setWidth(Integer width) {
        this.width = width;
    }

    public Integer getHeight() {
        return height;
    }

    public void setHeight(Integer height) {
        this.height = height;
    }
}

当JSON字段将1：1映射到类字段名称时，您不必使用此批注。当JSON使用与Java类不同的命名时，它是必需的。

使用Jackson映射JSON时遇到问题

1 个答案: