今天遇到一个这样的问题:需要把json串返序列化成对象,但是有些json串的某些值是不对了,类型为List的值为空时,json串里的内容是 “” 而不是 [],最终想到用注解
@JsonDeserialize 来解决,下面是一个代码例子。
我们的对象:
public class Student implements Serializable{ private String name; private String country; private List<String> courseList; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } public List<String> getCourseList() { return courseList; } @JsonDeserialize(using = StudentCourseDeserializer.class,as = List.class,contentAs = String.class) public void setCourseList(List<String> courseList) { this.courseList = courseList; } }
自己的反序列化注解:
import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.DeserializationContext; import com.fasterxml.jackson.databind.JsonDeserializer; import java.io.IOException; import java.util.ArrayList; import java.util.List; public class StudentCourseDeserializer extends JsonDeserializer<List>{ @Override public List deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException { Object value = jsonParser.readValueAs(Object.class); if(value instanceof List){ return (List)value; }else return null; } }
应用实例:
public class JacksonTest { public static void main(String[] args) throws Exception{ ObjectMapper objectMapper = new ObjectMapper(); String studentJson = "{\"name\":\"小王\",\"country\":\"中国\",\"courseList\":\"\"}";//此处courseList节点值是 "",但是对应的对象中的courseList 却是一个List Student student1 = objectMapper.readValue(studentJson,Student.class); if(null != student1){ } } }