什么时候在Java中使用Jackson来使用@JsonValue注释？
@JsonValue注释是在方法级别是有用的。我们可以使用此批注从java对象生成JSON字符串。如果要打印序列化的对象，则重写toString()方法。但是，使用@JsonValue批注，我们可以定义一种Java对象序列化的方式。
语法
@Target(value={ANNOTATION_TYPE,METHOD,FIELD})
@Retention(value=RUNTIME)
public @interface JsonValue示例
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonValue;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class JsonValueAnnotationTest {
public static void main(String args[]) throws Exception {
ObjectMapper mapper = new ObjectMapper();
String jsonString = mapper.writeValueAsString(new Student());
System.out.println(jsonString);
}
}// Student classclass Student {
@JsonProperty private int studentId = 115;
@JsonProperty private String studentName = "Sai Adithya";
@JsonValue public String toJson() {
return this.studentName + "," + this.studentId + "," + this.toString();
}
@Override public String toString() {
return "Student[" +
"studentId = " + studentId +
", studentName = " + studentName +
']';
}
}输出结果
"Sai Adithya,115,Student[studentId = 115, studentName = Sai Adithya]"