java - 使用 Jackson 解析 JSON 节点内部的 JSON 节点

Question

所以我是 Jackson 库的新手，我正在尝试解析 JSON 文件中的一个节点，该文件中包含其他节点，例如，它看起来像这样:

{ "node1": "value1",
  "node2": "value2",
  "node3": {
           "innerNode1": "value1",
           "innerNode2": "value2"
           }
}

我想要做的是在一个类中定义整个节点，然后让node3成为它自己的单独的类，它的行为就像用Jackson解析的常规Java对象一样，所以它具有所有相同的setter和getter方法。因此，我希望能够执行类似调用 masterNode.getNode1 并让它输出 value1 的操作，但也能够调用 node3.getInnerNode1 并让它输出 value1

我不确定如何完成这样的事情，任何帮助将不胜感激!

编辑:这是我正在使用的代码:

protected void onPostExecute(ContactInfo[] result) {
        int length = result.length;
        ArrayList<ContactInfo> contacts = new ArrayList<ContactInfo>();
        ArrayList<String> names = new ArrayList<String>();
        ArrayList<PhoneNumber> numberMap = new ArrayList<PhoneNumber>();
        ArrayList<String> workNumber = new ArrayList<String>();

        for (int i = 0; i < length; i++) {
            contacts.add(result[i]);
        }

        for (int i = 0; i < length; i++) {
            names.add(contacts.get(i).getName());
        }

        for (int i = 0; i < length; i++) {
            numberMap.add(contacts.get(i).getPhoneNumber());
        }

        for(PhoneNumber num: numberMap) {
            workNumber.add(num.getWork());
        }

        adapter = new ArrayAdapter<String>(local, R.layout.list_item, R.id.contactName, workNumber);

        setListAdapter(adapter);
    }

就一切而言，在我尝试从 PhoneNumber 类中获取实际号码之前，没有任何问题，这就是它给我一个 NullPointerError 的地方。我已经设置了类，但是它们很长，因为有很多字段，但我已经测试了这段代码，它正确地抓取了东西，所有这些，故障是在尝试从 PhoneNumber 类中抓取东西时(即“工作”号码)。

编辑:ContactInfo 类:

package com.example.codingchallenge;

import java.util.Map;

public class ContactInfo {
private String name, company, detailsURL, smallImageURL;
private int employeeId, birthdate;
private PhoneNumber phone;

public String getName() {
    return name;
}

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

public String getCompany() {
    return company;
}

public void setCompany(String company) {
    this.company = company;
}

public String getDetailsURL() {
    return detailsURL;
}

public void setDetailsURL(String detailsURL) {
    this.detailsURL = detailsURL;
}

public String getSmallImageURL() {
    return smallImageURL;
}

public void setSmallImageURL(String smallImageURL) {
    this.smallImageURL = smallImageURL;
}

public int getEmployeeId() {
    return employeeId;
}

public void setEmployeeId(int employeeId) {
    this.employeeId = employeeId;
}

public int getBirthdate() {
    return birthdate;
}

public void setBirthdate(int birthdate) {
    this.birthdate = birthdate;
}

public PhoneNumber getPhoneNumber() {
    return phone;
}

public void setPhoneNumber(PhoneNumber phone) {
    this.phone = phone;
}

}

Answer 1

代码:

public static class ContactInfo {
    private String name;
    private PhoneNumber phoneNumber;

    public String getName() {
        return name;
    }

    public PhoneNumber getPhoneNumber() {
        return phoneNumber;
    }

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

    public void setPhoneNumber(PhoneNumber phoneNumber) {
        this.phoneNumber = phoneNumber;
    }
}

public static class PhoneNumber {
    private String work;

    public String getWork() {
        return work;
    }

    public void setWork(String work) {
        this.work = work;
    }
}

public static void main(String[] args) throws JsonGenerationException, JsonMappingException, IOException {

    // POJO
    ContactInfo info1 = new ContactInfo();
    info1.setName("Neel1");
    PhoneNumber num = new PhoneNumber();
    num.setWork("123 456 7890");
    info1.setPhoneNumber(num);

    String json = new ObjectMapper().defaultPrettyPrintingWriter().writeValueAsString(info1);
    System.out.println(json);

    // From JSON
    String info2Json = "{ \"name\" : \"Neel2\", \"phoneNumber\" : { \"work\" : \"098 765 4321\" } }";
    ContactInfo info2 = new ObjectMapper().readValue(info2Json, ContactInfo.class);

    doSomething(new ContactInfo[] { info1, info2 });
}

private static void doSomething(ContactInfo[] result) {
    for(ContactInfo each : result) {
        String name = each.getName();
        String workPhone = each.getPhoneNumber().getWork();
        doSomething(name, workPhone);
    }

}

private static void doSomething(String name, String workPhone) {
    System.out.println("name: " + name + ", work: " + workPhone);
}

输出:

{
  "name" : "Neel1",
  "phoneNumber" : {
    "work" : "123 456 7890"
  }
}
name: Neel1, work: 123 456 7890
name: Neel2, work: 098 765 4321