@JsonValue 注释在方法级别很有用。我们可以使用此注释从 java 对象生成 JSON 字符串。如果我们想打印序列化对象,则重写 toString() 方法。但是使用@JsonValue注解,我们可以定义java对象序列化的方式。
@Target(value={ANNOTATION_TYPE,METHOD,FIELD}) @Retention(value=RUNTIME) public @interface JsonValue
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 class class 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 + ']'; } }
"Sai Adithya,115,Student[studentId = 115, studentName = Sai Adithya]"
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