使用Jackson将ArrayList中的每个元素保存到新行中

问题描述

我有一个POJO：

public class Game {

    private String title;

    private Set<String> genres;

    private String size;

    private List<String> screenshots;
}

我想将Game对象保存为JSON。 ObjectMapper配置：

public static ObjectMapper mapper = new ObjectMapper()
            .configure(DeserializationFeature.FAIL_ON_UNKNowN_PROPERTIES,false)
            .setVisibility(PropertyAccessor.FIELD,JsonAutoDetect.Visibility.ANY)
            .enable(SerializationFeature.INDENT_OUTPUT);

将对象保存为JSON： mapper.writeValue(new File(PATH),game)

JSON如下：

{
  "title" : "Dead Cells","genres" : [ "Action" ],"size" : "761M","screenshots" : [ "https://lh3.googleusercontent.com/af9mFH4XinZ7f6dx-Ygm9molYPAcMHhhZyQ0udDBd9S9-44v_VBdeA0rjSlQyJRpQg=w1440-h620-rw","https://lh3.googleusercontent.com/mo0CZaV_aGflOPB8Tzo697l1WoZuoYUN9TiPMWq0zE29v_I99n1Qg185MfHrU-53nxAG=w1440-h620-rw","https://lh3.googleusercontent.com/FEiHmVyoT1MU3rbAxSkE_aNDuXBuo3YHQOnqfMAfehS-d4k6CvxuyxpX6KKSbJp3Xv28=w1440-h620-rw","https://lh3.googleusercontent.com/3Zg_EtwMpt-vWNBTdCNE7hP8M6qeDMq91HKfx70FSJ5tVAsPxHkTYWGiCwvHg5ucMykK=w1440-h620-rw","https://lh3.googleusercontent.com/A9K6iPYty9IvkzeO_29ONdPAnFFs1BBzk6w-dAf1s5JgpZFMpxc5wpbz07fzovJWxlzO=w1440-h620-rw" ]
}

如您所见，所有屏幕截图都像一个字符串一样打印，但是我想要这样的结果：

{
  "title" : "Dead Cells","screenshots" : [ "https://lh3.googleusercontent.com/af9mFH4XinZ7f6dx=w1440-h620-rw","https://lh3.googleusercontent.com/I99n1Qg185MfHrU-53nxAG=w1440-h620-rw","https://lh3.googleusercontent.com/d4k6CvxuyxpX6KKSbJp3Xv28=w1440-h620-rw","https://lh3.googleusercontent.com/wvHg5ucMykK=w1440-h620-rw",]
}

我该怎么办？

解决方法

您可以像下面的代码那样使用ObjectMapper的writerWithDefaultPrettyPrinter：

Game game = new Game();
ObjectMapper mapper = new ObjectMapper();
File file = new File("pretty-print.json");
mapper.writerWithDefaultPrettyPrinter().writeValue(file,game);

您的数据输出为：

{
  "title" : "Dead Cells","genres" : [ "Action" ],"size" : "761M","screenshots" : [ 
"https://lh3.googleusercontent.com/af9mFH4XinZ7f6dx-Ygm9molYPAcMHhhZyQ0udDBd9S9-44v_VBdeA0rjSlQyJRpQg=w1440-h620-rw","https://lh3.googleusercontent.com/mo0CZaV_aGflOPB8Tzo697l1WoZuoYUN9TiPMWq0zE29v_I99n1Qg185MfHrU-53nxAG=w1440-h620-rw","https://lh3.googleusercontent.com/FEiHmVyoT1MU3rbAxSkE_aNDuXBuo3YHQOnqfMAfehS-d4k6CvxuyxpX6KKSbJp3Xv28=w1440-h620-rw","https://lh3.googleusercontent.com/3Zg_EtwMpt-vWNBTdCNE7hP8M6qeDMq91HKfx70FSJ5tVAsPxHkTYWGiCwvHg5ucMykK=w1440-h620-rw","https://lh3.googleusercontent.com/A9K6iPYty9IvkzeO_29ONdPAnFFs1BBzk6w-dAf1s5JgpZFMpxc5wpbz07fzovJWxlzO=w1440-h620-rw" ]
}