GSON fromJson 没有为 Java 字段赋值

Question

我有一个 Json 字符串 "{"value":"3A72fd4ccb-1980-26cf-8db3-9eaadf1205c2"}", 同时将相同的字符串传递给以下代码：

Gson headerGson = new GsonBuilder().create();
Object  ob = headerGson.fromJson(jsonStr, cl);

结果对象未分配给 "value" is json 字符串。当我尝试使用 ReflectionAPI 打印对象字段时，我得到：这些字段是：值对应字段类型 --> class java.lang.String 对应的值为--> null

我在fromJson方法中作为"cl"传递的javaclass如下：

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "AttributedURI", propOrder = {
    "value"
})
public class AttributedURI {
@XmlValue
@XmlSchemaType(name = "anyURI")
protected String value;
@XmlAnyAttribute
private Map<QName, String> otherAttributes = new HashMap<QName, String>();

/**
 * Gets the value of the value property.
 * 
 * @return
 *     possible object is
 *     {@link String }
 *     
 */
public String getValue() {
    return value;
}

/**
 * Sets the value of the value property.
 * 
 * @param value
 *     allowed object is
 *     {@link String }
 *     
 */
public void setValue(String value) {
    this.value = value;
}

/**
 * Gets a map that contains attributes that aren't bound to any typed property on this class.
 * 
 * <p>
 * the map is keyed by the name of the attribute and 
 * the value is the string value of the attribute.
 * 
 * the map returned by this method is live, and you can add new attribute
 * by updating the map directly. Because of this design, there's no setter.
 * 
 * 
 * @return
 *     always non-null
 */
public Map<QName, String> getOtherAttributes() {
    return otherAttributes;
}

}

请让我知道我在这里遗漏了什么。

Answer 1

Class AttributedURI代表你的json的内部：{"value":"3A72fd4ccb-1980-26cf-8db3-9eaadf1205c2"}。所以，当你执行 methodheaderGson.fromJson(jsonStr, cl) 时，Gson 试图在 AttributedURI class 中找到 MessageID 字段，这显然是不存在的。要反序列化您的 json，您可以将 AttributedURI 包装在其他 class 中。例如：

public class OuterClass {
    @SerializedName("MessageID")
    private AttributedURI messageID;

    public AttributedURI getMessageID(){
          return messageID;
    }
}

我也怀疑你在这里需要 XML 注释：afaik，GSON 作品不需要它们。

另外，Gson#fromJson是泛型方法，所以可以这样写：

 OuterClass  ob = headerGson.fromJson(jsonStr, OuterClass.class);

GSON fromJson 没有为 Java 字段赋值

GSON fromJson is not assigning values to the Java fields

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json

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