如何使用Java中的Jackson库忽略JSON对象的字段？
Jackson@JsonIgnore批注可用于忽略Java对象的某些属性 或字段 。在将JSON读取到Java对象中以及将Java对象写入JSON中时，都可以忽略该属性。我们可以使用ObjectMapper 类的readValue()和writeValueAsString()方法将JSON读取到JavaObject并将Java对象写入JSON。
语法
@Target(value={ANNOTATION_TYPE,METHOD,CONSTRUCTOR,FIELD})
@Retention(value=RUNTIME)
public @interface JsonIgnore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 classclass 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 + "]";
}
}输出结果
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]