Question

我有一个像这样的JSON结构：

{
    "text" : "MVA/Transport. Greater Hume (Hume Hwy, Holbrook, NSW 2644) at 7 Mar 2017 03:58 #NSWRFS #MVATransport",
    "user" : {
        "id" : "4721717942",
        "name" : "NSW Fire Updates"
    },
    "lang" : "en",
    "coordinates" : {
        "coordinates" : [147.273696, -35.785469],
        "type" : "Point"
    },
    "created_at" : "Mon Mar 06 17:29:31 +0000 2017"
}

我在解析coordinates对象中的coordinates数组时遇到问题。

public class ParsingTweet {

    public static void main(String[] args) throws IOException {
        assert args != null & args.length > 0;
        List<Tweet> tweets = new ArrayList<>();
        ObjectMapper mapper = new ObjectMapper();
        try (BufferedReader reader = new BufferedReader(new FileReader("tweets.json"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                tweets.add(mapper.readValue(line, Tweet.class));
            }
        }
        System.out.println(tweets);
    }

}

其中coordinates打印为：

coordinates = ClassPojo [type = Point, coordinates = [Ljava.lang.Double;@1810399e]]

而不是：

coordinates = ClassPojo [type = Point, coordinates = [147.273696, -35.785469]]

以下是我的POJO：

@JsonIgnoreProperties(ignoreUnknown = true)
public class Tweet {

    private String text;
    private String created_at;
    private User user;
    private Coordinates coordinates;

    public Tweet(){
    }

    public String getText()
    {
        return text;
    }
    public void setText(String text)
    {
        this.text = text;
    }
    public String getCreated_at()
    {
        return created_at;
    }
    public void setCreated_at(String created_at)
    {
        this.created_at = created_at;
    }
    public User getUser()
    {
        return user;
    }
    public void setUser(User user)
    {
        this.user = user;
    }
    public Coordinates getCoordinates()
    {
        return coordinates;
    }
    public void setCoordinates(Coordinates coordinates)
    {
        this.coordinates = coordinates;
    }

    @Override
    public String toString()
    {
        return "[text = "+text+", created_at = "+created_at+", user = "+user+", coordinates = "+coordinates+"]";
    }
}



public class Coordinates {
    private String type;
    private String[] coordinates;
    public String getType ()
    {
        return type;
    }
    public void setType (String type)
    {
        this.type = type;
    }
    public String[] getCoordinates()
    {
        return coordinates;
    }
    public void setCoordinates (String[] coordinates)
    {
        this.coordinates = coordinates;
    }

    @Override
    public String toString()
    {
        return "ClassPojo [type = "+type+", coordinates = "+coordinates+"]";
    }
}

Answer 1

可以尝试在String[]中从List<String>更改为Coordinate。

它看起来像Double[]一样？虽然我不明白为什么，因为您的Coordinate课程有String[]字段。

考虑一下你是否拥有1个值或2个以上值的JSON数组 - 即使它们不是有效的坐标，解析器也会很乐意将其解析为Java List或数组。

如果您的double[] POJO具有String[]，那么它不会解析为List<String>，Coordinate或double latitude，而是更好和double longitude作为属性。您可以使用JSON解析库执行此操作，或者您可以将其视为API模型的第一个转换解析，然后再将其转换为您的域模型。

Answer 2

您正在打印数组...所以您需要正确地执行此操作

@Override
public String toString()
{
    return  + Coordinates.class.getSimpleName() 
        + " [type = " + type 
        + ", coordinates = " + Arrays.toString(coordinates)
        + "]";
}

如何将JSON数组解析为POJO

2 个答案: