@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。
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"sai adithya,115,student[studentid = 115, studentname = sai adithya]"
以上就是在java中使用jackson时，何时使用@jsonvalue注解？的详细内容。