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法律學如何使用 Java 中的 @JsonCreator 註解來反序列化 JSON 字串?
@JsonProperty 註解可用於指示 JSON 中的屬性名稱。此註解可用於建構函式 或工廠方法。@JsonCreator註解在不可使用@JsonSetter註解的情況下非常有用。例如，不可變物件沒有 setter 方法，因此需要將它們的初始值注入到建構函式中。
@JsonProperty - 建構函式
示例
import com.fasterxml.jackson.annotation.*;
import java.io.IOException;
import com.fasterxml.jackson.databind.*;
public class JsonCreatorTest1 {
public static void main(String[] args) throws IOException {
ObjectMapper om = new ObjectMapper();
String jsonString = "{\"id\":\"101\", \"fullname\":\"Ravi Chandra\", \"location\":\"Pune\"}";
System.out.println("JSON: " + jsonString);
Customer customer = om.readValue(jsonString, Customer.class);
System.out.println(customer);
}
}
// Customer class
class Customer {
private String id;
private String name;
private String address;
public Customer() {
}
@JsonCreator
public Customer(
@JsonProperty("id") String id,
@JsonProperty("fullname") String name,
@JsonProperty("location") String address) {
this.id = id;
this.name = name;
this.address = address;
}
@Override
public String toString() {
return "Customer [id=" + id + ", name=" + name + ", address=" + address + "]";
}
}輸出
JSON: {"id":"101", "fullname":"Ravi Chandra", "location":"Pune"}
Customer [id=101, name=Ravi Chandra, address=Pune]@JsonCreator - 工廠方法
示例
import com.fasterxml.jackson.annotation.*;
import java.io.IOException;
import com.fasterxml.jackson.databind.*;
public class JsonCreatorTest2 {
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
String jsonString = "{\"id\":\"102\", \"fullname\":\"Raja Ramesh\", \"location\":\"Hyderabad\"}";
System.out.println("JSON: " + jsonString);
Customer customer = mapper.readValue(jsonString, Customer.class);
System.out.println(customer);
}
}
// Customer class
class Customer {
private String id;
private String name;
private String address;
public Customer() {
}
@JsonCreator
public static Customer createCustomer(
@JsonProperty("id") String id,
@JsonProperty("fullname") String name,
@JsonProperty("location") String address) {
Customer customer = new Customer();
customer.id = id;
customer.name = name;
customer.address = address;
return customer;
}
@Override
public String toString() {
return "Customer [id=" + id + ", name=" + name + ", address=" + address + "]";
}
}輸出
JSON: {"id":"101", "fullname":"Raja Ramesh", "location":"Hyderabad"}
Customer [id=102, name=Raja Ramesh, address=Hyderabad]
更新於: 17-2-2020
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