[英]Convert a part of Json to HashMap using Jackson ObjectMapper
I am trying to unmarshall a json file in a way such that few properties of Json are mapped into a HashMap that is present in my model class.Rest of the properties are mapped to the respective fields of the class.Please find the Json below: 我试图以一种方式解组json文件,使得Json的少数属性被映射到我的模型类中存在的HashMap。属性的重置被映射到类的相应字段。请在下面找到Json:
{
"_id":2,
"Name":"xyz",
"Age":20,
"MEMO_TEXT":"yyy",
"MEMO_LINK":"zzz",
"MEMO_DOB":"",
"MEMO_USERNAME":"linie orange",
"MEMO_CATEGORY":2,
"MEMO_UID":"B82071415B07495F9DD02C152E4805EC"
}
And here is the Model class to which I want to map this Json: 这里是我要映射这个Json的Model类:
public class Model{
private int _id;
private String name;
private int age
private HashMap<String, String> columns;
//Getters and Setter methods
}
So here, what i want is to get a map columns
that contains keys "MEMO_TEXT","MEMO_LINK","MEMO_DOB","MEMO_USERNAME","MEMO_CATEGORY","MEMO_UID"
所以在这里,我想要的是获得一个包含键
"MEMO_TEXT","MEMO_LINK","MEMO_DOB","MEMO_USERNAME","MEMO_CATEGORY","MEMO_UID"
的地图columns
and rest of the properties in Json are mapped to their respective fields. Json中的其余属性映射到它们各自的字段。
Is it possible to do this using ObjectMapper of Jackson Library? 是否可以使用杰克逊图书馆的ObjectMapper来做到这一点?
You can use @JsonAnySetter to annotate a method to be called for "other" properties: 您可以使用@JsonAnySetter来注释要为“其他”属性调用的方法:
@Test
public void partial_binding() throws Exception {
Model model = mapper.readValue(Resources.getResource("partial_binding.json"), Model.class);
assertThat(model.name, equalTo("xyz"));
assertThat(model.columns, hasEntry("MEMO_TEXT", "yyy"));
assertThat(
mapper.writeValueAsString(model),
json(jsonObject()
.withProperty("Name", "xyz")
.withProperty("MEMO_TEXT", "yyy")
.withAnyOtherProperties()));
}
public static class Model {
@JsonProperty
private int _id;
@JsonProperty("Name")
private String name;
@JsonProperty("Age")
private int age;
private HashMap<String, String> columns;
@JsonAnyGetter
public HashMap<String, String> getColumns() {
return columns;
}
public void setColumns(HashMap<String, String> columns) {
this.columns = columns;
}
@JsonAnySetter
public void putColumn(String key, String value) {
if (columns == null) columns = new HashMap<>();
columns.put(key, value);
}
}
Also, @JsonAnyGetter does "kind of the reverse", so this should serialize and deserialize the same way. 此外,@ JsonAnyGetter做了“反向”,所以这应该以相同的方式序列化和反序列化。
One of several ways to achieve what you want is to add a constructor: 实现所需内容的几种方法之一是添加构造函数:
@JsonCreator
public Model(Map<String, Object> fields) {
this._id = (int) fields.remove("_id");
this.name = (String) fields.remove("Name");
this.age = (int) fields.remove("Age");
this.columns = new HashMap<String, String>();
for (Entry<String, Object> column : fields.entrySet()) {
columns.put(column.getKey(), column.getValue().toString());
}
}
Be aware that if you serialize it back to JSON the structure will be diffrent than the initial one. 请注意,如果将其序列化为JSON,则结构将与初始结构不同。
Try using a SerializerProvider. 尝试使用SerializerProvider。 A SerializerProvider can modify the deserialization, enabling custom deserialization.
SerializerProvider可以修改反序列化,从而启用自定义反序列化。
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