Question

我按照http://tutorials.jenkov.com/java-json/jackson-objectmapper.html上的教程进行操作，并且syntex中没有错误。在代码中似乎没有问题，我已经使用向Netbeans项目添加库的标准方法在Netbeans中将JACKSON jar文件添加到库中。我仍然无法将JSON字符串转换为java对象。这是我的代码。

class Car {

    private int doors;
    private String brand;

    public int getDoors() {
        return doors;
    }

    public void setDoors(int doors) {
        this.doors = doors;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    void printCar() {
        System.out.println("car.brand = " + getBrand());
        System.out.println("car.doors = " + getDoors());
    }

}//class Car ends here.

以下是使用ObjectMapper类的方法readValue的代码

import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ObjectMapperExampleWithString1 {

    public static void main(String args[]) {
        ObjectMapper objectMapper = new ObjectMapper();

        String carJson
                = "{ \"brand\" : \"Mercedes\", \"doors\" : 5 }";

        Car car = null;
        try {
            car = objectMapper.readValue(carJson, Car.class);
        } catch (IOException ex) {
            Logger.getLogger(ObjectMapperExampleWithString1.class.getName()).log(Level.SEVERE, null, ex);
        }
        if (car != null){
            car.printCar();
        }else{
            System.out.println("Object car of type Car is null. Problem!!!");
        }

    }
}

这是我得到的例外。

运行：线程＆＃34; main＆＃34;中的例外情况java.lang.NoSuchMethodError：com.fasterxml.jackson.databind.JavaType.isReferenceType（）Z 在com.fasterxml.jackson.databind.deser.BasicDeserializerFactory.findDefaultDeserializer（BasicDeserializerFactory.java:1522）在com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.findStdDeserializer（BeanDeserializerFactory.java:167）在com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.createBeanDeserializer（BeanDeserializerFactory.java:132）在com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2（DeserializerCache.java:403）在com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer（DeserializerCache.java:352）在com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2（DeserializerCache.java:264）在com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer（DeserializerCache.java:244）在com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer（DeserializerCache.java:142） at com.fasterxml.jackson.databind.DeserializationContext.findRootValueDeserializer（DeserializationContext.java:461） at com.fasterxml.jackson.databind.ObjectMapper._findRootDeserializer（ObjectMapper.java:3804） at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose（ObjectMapper.java:3698） at com.fasterxml.jackson.databind.ObjectMapper.readValue（ObjectMapper.java:2714） at myJackson.ObjectMapperExampleWithString1.main（ObjectMapperExampleWithString1.java:18） Java结果：1 建立成功（总时间：0秒）

Jackson objectMapper.readValue（）没有从字符串

0 个答案: