如何使用 Java 中的 @JsonCreator 注释反序列化 JSON 字符串?
javajsonobject oriented programmingprogramming
@JsonProperty 注释可用于指示 JSON 中的 属性名称。此注释可用于 构造函数 或 工厂方法。@JsonCreator 注释在无法使用 @JsonSetter 注释的情况下很有用。例如，不可变对象没有任何 setter 方法，因此它们需要将其初始值注入构造函数中。
@JsonProperty - 构造函数
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 + "]";
}
}
输出
JSON: {"id":"101", "fullname":"Ravi Chandra", "location":"Pune"}
Customer [id=101, name=Ravi Chandra, address=Pune]
@JsonCreator - Factory 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 + "]";
}
}
输出
JSON: {"id":"101", "fullname":"Raja Ramesh", "location":"Hyderabad"}
Customer [id=102, name=Raja Ramesh, address=Hyderabad]
