使用Jackson解析和未命名的数组 [英] Use Jackson to parse and unnamed array

问题描述

好的，所以我使用Jackson来解析一个JSON文件，问题是，该文件是一个大的未命名数组。它的格式为：

OK, so I'm using Jackson to parse a JSON file, problem is, the file is one big unnamed array. It is in the format:

[{json stuff}，{json stuff}，...，{json stuff}]

所有 json的东西只是我必须处理的常规JSON表达式实际上把它变成一个数组。

All the json stuff is just regular JSON expressions that I will have to deal with once I actually get this into an array.

我找不到任何有关如何使用Jackson映射事物的真实教程，但需要找到一种方法来映射这些不同的将事物分解为数组，然后使用Jackson将每个特定事物解析为其中的各个组件。知道怎么做吗？

I can't find any real tutorials about how to map things using Jackson, but need to find a way to map each of these different things into an array, and then parse each specific thing using Jackson into it's individual components. Any idea how to do this?

P.S。我能找到的唯一真正的教程是： http：// www .studytrails.com / java / json / java-jackson-Data-Binding.jsp

P.S. The only real tutorial I could find was this: http://www.studytrails.com/java/json/java-jackson-Data-Binding.jsp

其中DataSet []是在文件中命名的数组。我想弄清楚如何做该教程所做的事情，除了上面的例子，数组不以名字开头。

Where DataSet[] is an array that is named in the file. I want to figure out how to do what that tutorial does, except with the example above, where the array does not start off with a name.

P.P.S。这是我正在使用的代码：

P.P.S. Here is the code I'm using:

要映射到我的项目的基本杰克逊代码：

Basic Jackson code to map into my item:

ObjectMapper mapper = new ObjectMapper();
    mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

    URL url = null;
    try {
        url = new URL("my JSON URL");
    } catch (MalformedURLException e) {
        e.printStackTrace();
    }

    try {
        ContactInfo contacts = mapper.readValue(url, ContactInfo.class);
    } catch (JsonParseException e) {
        e.printStackTrace();
    } catch (JsonMappingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

然后我的ContactInfo类只是Getters和Setters，其中包含已定义的字段JSON URL。问题是，没有分配所有不同JSON节点的数组的名称，我不知道如何访问单个联系人值，或者是否被覆盖。

Then my ContactInfo class is just the Getters and Setters with the defined fields in the JSON URL. The problem is, without a name to the Array that breaks up all the different JSON nodes, I don't know how to access individual contact values, or if they are being overwritten.

推荐答案

只需使用 ContactInfo [] 作为类类型。这是一个工作示例。

Just use a ContactInfo[] as the class type. Here's a working example.

public class Example {
    public static void main(String[] args) throws Exception {
        String json = "[{\"name\":\"random\"},{\"name\":\"random\"},{\"name\":\"random\"}]";
        ObjectMapper mapper = new ObjectMapper();
        ContactInfo[] contactInfos = mapper.readValue(json, ContactInfo[].class);
        System.out.println(contactInfos.length);
    }

    static class ContactInfo {
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    } 
}

或者，您可以使用列表< ContactInfo> ，但您需要 TypeReference 。

Alternatively, you can use a List<ContactInfo>, but you'll need a TypeReference.

List<ContactInfo> contactInfos = mapper.readValue(json, new TypeReference<List<ContactInfo>>() {});
System.out.println(contactInfos.size());

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