如何在Java中使用Jackson库忽略JSON对象的字段？

Jackson @JsonIgnore 注释可用于忽略某个属性或字段一个 Java 对象。将 JSON 读入 Java 对象以及将 Java 对象写入 JSON 时，都可以忽略该属性。我们可以使用ObjectMapper类的readValue()和writeValueAsString()方法将JSON读取为Java对象并将Java对象写入JSON。

语法

@Target(value={ANNOTATION_TYPE,METHOD,CONSTRUCTOR,FIELD})
@Retention(value=RUNTIME)
public @interface JsonIgnore

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示例

import java.io.*;
import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.databind.*;
public class JsonIgnoreTest {
public static void main(String[] args) throws IOException {
Customer customer = new Customer("110", "Surya Kiran", "Chennai");
System.out.println(customer);
ObjectMapper mapper = new ObjectMapper();
String jsonString = mapper.writeValueAsString(customer);
System.out.println("JSON: " + jsonString);
System.out.println("---------");
jsonString = "{"id":"120","name":"Devaraj", "address":"Banglore"}";
System.out.println("JSON: " + jsonString);
customer = mapper.readValue(jsonString, Customer.class);
System.out.println(customer);
}
}
// Customer class
class Customer {
private String id;
private String name;
@JsonIgnore
private String address;
public Customer() {
}
public Customer(String id, String name, String address) {
this.id = id;
this.name = name;
this.address = address;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public String getAddress() {
return address;
}
@Override
public String toString() {
return "Customer [id=" + id + ", name=" + name + ", address=" + address + "]";
}
}

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输出

Customer [id=110, name=Surya Kiran, address=Chennai]
JSON: {"id":"110","name":"Surya Kiran"}
---------
JSON: {"id":"120","name":"Devaraj", "address":"Banglore"}
Customer [id=120, name=Devaraj, address=null]

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