如何使用jackson制作POJO并解析递归对象？ [英] How to make POJO and parse recursive objects using jackson?
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问题描述
我有一个以下JSON响应，我从休息服务回来。现在我需要将JSON响应下面的反序列化反转为POJO。我正在和杰克逊合作。
I have a below JSON response that I am getting back from a rest service. Now I need to deserialize below JSON response into a POJO. I am working with Jackson.
{
"pagination": {
"number": 1,
"entriesPerPage": 200,
"total": 3
},
"postings": [{
"categories": [{
"taskid": "79720",
"name": "Sunglasses",
"parentCategory": {
"taskid": "394",
"name": "Sunglasses & Fashion Eyewear",
"parentCategory": {
"taskid": "2340",
"name": "Men's Accessories",
"parentCategory": {
"taskid": "10987",
"name": "Clothing, Shoes & Accessories"
}
}
}
}]
},
{
"categories": [{
"taskid": "12980",
"name": "Toys",
"parentCategory": {
"taskid": "123",
"name": "Fashion",
"parentCategory": {
"taskid": "78765",
"name": "Men's Accessories"
}
}
}]
}],
"total": 2
}
在上面的json中，发布是一个JSON数组，可以有多个发布 json对象。现在类别也是JSON数组。现在棘手的部分是我可以在每个类别对象中有多个级别的 parentCategory ，我不知道有多少级别的 parentCategory 我会的。给出以上JSON，我需要提取每个类别的 taskid 和 taskId 的最后 parentCategory 。所以它应该是这样的：
In above json, postings is a JSON array which can have multiple posting json object. Now categories is also JSON array. Now tricky part is I can have multiple levels of parentCategory inside each category object and I don't know how many levels of parentCategory I will have. Give above JSON, I need to extract taskid of each category and taskId of last parentCategory. So it should be like this:
79720=10987
12980=78765
其中 79720 是类别的taskId而 10987 是最后 parentCategory 的taskId。与其他人类似。
Where 79720 is taskId of category and 10987 is the taskId of last parentCategory. Similarly for other one.
下面是我的代码，我通过进行http调用将JSON反序列化到我的POJO中：
Below is my code where I am deserializing JSON into my POJO by making an http call:
ResponseEntity<Stuff> responseEntity = HttpClient.getInstance().getClient()
.exchange(URI.create(endpoint), HttpMethod.POST, requestEntity, Stuff.class);
Stuff response = responseEntity.getBody();
List<Posting> postings = response.getPostings();
for(Posting postings : postings) {
//....
}
我遇到的困惑是 - 如何为上面的JSON制作POJO？我尝试使用 jsonschema2pojo ，但它没有为 parentCategory 。因为我可以拥有嵌套级别的parentCategory，这是我手头不知道的。
Confusion I have is - How to make POJO for above JSON? I tried using jsonschema2pojo but it's not making right classes for parentCategory. Since I can have nested levels of parentCategory which I don't know before hand.
使用Jackson可以做到吗？
Is this possible to do using Jackson?
这是为 Category 和 ParentCategory 生成的POJO类。我不确定是否需要在此处进行任何更改，以便我可以解析递归 parentCategory 对象。
This is the POJO class generated for Category and ParentCategory. I am not sure whether I need to make any changes here so that I can parse recursive parentCategory object.
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"taskid", "name", "parentCategory"})
public class Category {
@JsonProperty("taskid")
private String taskid;
@JsonProperty("name")
private String name;
@JsonProperty("parentCategory")
private ParentCategory parentCategory;
@JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();
...
}
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"taskid", "name", "parentCategory"})
public class ParentCategory {
@JsonProperty("taskid")
private String taskid;
@JsonProperty("name")
private String name;
@JsonProperty("parentCategory")
private ParentCategory parentCategory;
@JsonIgnore
private Map<String, Object> additionalProperties = new HashMap<String, Object>();
...
}
推荐答案
这次我将使用 GSon
以较少的工作量管理递归。
Which manages recursion with less effort.
Pojos可以从json2pojo网站制作，只需选择GSon作为JSon库。
Pojos can be made from json2pojo website, simply choosing GSon as JSon library.
这些是Pojos：
import java.io.Serializable;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Pagination implements Serializable
{
public Pagination() {
super();
// TODO Auto-generated constructor stub
}
@SerializedName("number")
@Expose
private Integer number;
@SerializedName("entriesPerPage")
@Expose
private Integer entriesPerPage;
@SerializedName("total")
@Expose
private Integer total;
private final static long serialVersionUID = 5114620434202813556L;
public Integer getNumber() {
return number;
}
public void setNumber(Integer number) {
this.number = number;
}
public Integer getEntriesPerPage() {
return entriesPerPage;
}
public void setEntriesPerPage(Integer entriesPerPage) {
this.entriesPerPage = entriesPerPage;
}
public Integer getTotal() {
return total;
}
public void setTotal(Integer total) {
this.total = total;
}
}
import java.io.Serializable;
import java.util.List;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Categories implements Serializable
{
public Categories() {
super();
// TODO Auto-generated constructor stub
}
@SerializedName("pagination")
@Expose
private Pagination pagination;
@SerializedName("postings")
@Expose
private List<Posting> postings = null;
@SerializedName("total")
@Expose
private Integer total;
private final static long serialVersionUID = 4589512697836725240L;
public Pagination getPagination() {
return pagination;
}
public void setPagination(Pagination pagination) {
this.pagination = pagination;
}
public List<Posting> getPostings() {
return postings;
}
public void setPostings(List<Posting> postings) {
this.postings = postings;
}
public Integer getTotal() {
return total;
}
public void setTotal(Integer total) {
this.total = total;
}
}
import java.io.Serializable;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Category implements Serializable
{
public Category() {
super();
// TODO Auto-generated constructor stub
}
@SerializedName("taskid")
@Expose
private String taskid;
@SerializedName("name")
@Expose
private String name;
@SerializedName("parentCategory")
@Expose
private ParentCategory parentCategory;
private final static long serialVersionUID = -2127963072268572959L;
public String getTaskid() {
return taskid;
}
public void setTaskid(String taskid) {
this.taskid = taskid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public ParentCategory getParentCategory() {
return parentCategory;
}
public void setParentCategory(ParentCategory parentCategory) {
this.parentCategory = parentCategory;
}
}
import java.io.Serializable;
import java.util.List;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Posting implements Serializable
{
@SerializedName("categories")
@Expose
private List<Category> categories = null;
private final static long serialVersionUID = 8135185675909461065L;
public List<Category> getCategories() {
return categories;
}
public Posting() {
super();
// TODO Auto-generated constructor stub
}
public void setCategories(List<Category> categories) {
this.categories = categories;
}
}
import java.io.Serializable;
import java.util.List;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class ParentCategory implements Serializable
{
@SerializedName("taskid")
@Expose
private String taskid;
@SerializedName("name")
@Expose
private String name;
@SerializedName("parentCategory")
@Expose
private List<ParentCategory> parentCategory;
public ParentCategory() {
super();
// TODO Auto-generated constructor stub
}
private final static long serialVersionUID = -5989749742502713615L;
public String getTaskid() {
return taskid;
}
public void setTaskid(String taskid) {
this.taskid = taskid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<ParentCategory> getParentCategory() {
return parentCategory;
}
public void setParentCategory(List<ParentCategory> parentCategory) {
this.parentCategory = parentCategory;
}
}
所以这是一个测试实现：
So this is a test implementation:
Pagination pagination = new Pagination();
pagination.setNumber(1);
pagination.setEntriesPerPage(200);
pagination.setTotal(3);
Categories categories = new Categories();
categories.setPagination(pagination);
Category category = new Category();
category.setName("Sunglasses");
category.setTaskid("79720");
List<Category> categoryList = new ArrayList<Category>();
Posting posting = new Posting();
posting.setCategories(categoryList);
List<ParentCategory> parentCategoryList = new ArrayList<ParentCategory>();
List<ParentCategory> parentCategoryList2 = new ArrayList<ParentCategory>();
ParentCategory parentCategory1 = new ParentCategory();
parentCategory1.setName("Sunglasses & Fashion Eyewear");
parentCategory1.setTaskid("394");
ParentCategory parentCategory2 = new ParentCategory();
parentCategory2.setName("Men's Accessories");
parentCategory2.setTaskid("2340");
ParentCategory parentCategory3 = new ParentCategory();
parentCategory3.setName("Clothing, Shoes & Accessories");
parentCategory3.setTaskid("10987");
parentCategoryList.add(parentCategory2);
parentCategoryList2.add(parentCategory3);
parentCategory2.setParentCategory(parentCategoryList2);
parentCategory1.setParentCategory(parentCategoryList);
category.setParentCategory(parentCategory1);
Gson gson = new Gson();
System.out.println(gson.toJson(category));
...这是由此产生的Json：
...and this is the resulting Json:
{
"taskid": "79720",
"name": "Sunglasses",
"parentCategory": {
"taskid": "394",
"name": "Sunglasses \u0026 Fashion Eyewear",
"parentCategory": [{
"taskid": "2340",
"name": "Men\u0027s Accessories",
"parentCategory": [{
"taskid": "10987",
"name": "Clothing, Shoes \u0026 Accessories"
}]
}]
}
}
也许还需要一些调整，但你明白了。
Maybe still need a bit of tweaking but you got the idea.
希望有所帮助！
编辑：正如操作要求我添加杰克逊版本。
as the op requests I add the Jackson Version.
Pojos：
import java.io.Serializable;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"taskid", "name", "parentCategory"})
public class ParentCategory implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
@JsonProperty("taskid")
private String taskid;
@JsonProperty("name")
private String name;
@JsonProperty("parentCategory")
private ParentCategory parentCategory;
public String getTaskid() {
return taskid;
}
public void setTaskid(String taskid) {
this.taskid = taskid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public ParentCategory getParentCategory() {
return parentCategory;
}
public void setParentCategory(ParentCategory parentCategory) {
this.parentCategory = parentCategory;
}
}
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"taskid", "name", "parentCategory"})
public class Category implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
@JsonProperty("taskid")
private String taskid;
@JsonProperty("name")
private String name;
@JsonProperty("parentCategory")
private ParentCategory parentCategory;
public String getTaskid() {
return taskid;
}
public void setTaskid(String taskid) {
this.taskid = taskid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public ParentCategory getParentCategory() {
return parentCategory;
}
public void setParentCategory(ParentCategory parentCategory) {
this.parentCategory = parentCategory;
}
}
public class Test {
public static void main(String[] args) throws JsonProcessingException {
Category category = new Category();
category.setName("Sunglasses");
category.setTaskid("79720");
List<Category> categoryList = new ArrayList<Category>();
List<ParentCategory> parentCategoryList = new ArrayList<ParentCategory>();
List<ParentCategory> parentCategoryList2 = new ArrayList<ParentCategory>();
ParentCategory parentCategory1 = new ParentCategory();
parentCategory1.setName("Sunglasses & Fashion Eyewear");
parentCategory1.setTaskid("394");
ParentCategory parentCategory2 = new ParentCategory();
parentCategory2.setName("Men's Accessories");
parentCategory2.setTaskid("2340");
ParentCategory parentCategory3 = new ParentCategory();
parentCategory3.setName("Clothing, Shoes & Accessories");
parentCategory3.setTaskid("10987");
parentCategory1.setParentCategory(parentCategory2);
parentCategory2.setParentCategory(parentCategory3);
category.setParentCategory(parentCategory1);
ObjectMapper objectMapper = new ObjectMapper();
String testJson = objectMapper.writeValueAsString(category);
System.out.println(testJson);
}
}
再次测试结果如下：
{
"taskid": "79720",
"name": "Sunglasses",
"parentCategory": {
"taskid": "394",
"name": "Sunglasses & Fashion Eyewear",
"parentCategory": {
"taskid": "2340",
"name": "Men's Accessories",
"parentCategory": {
"taskid": "10987",
"name": "Clothing, Shoes & Accessories"
}
}
}
}
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