序列化与杰克逊(JSON) -得到“没有发现序列化器”?

当我试图使用Jackson序列化一个非常简单的对象时，我得到了一个异常。错误:

jsonmappingexception:没有找到序列化器类MyPackage。TestA和没有属性发现以创建BeanSerializer(为避免异常，禁用 SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS))

下面是要序列化的简单类和代码。

有人能告诉我为什么我得到这个错误吗?

public class TestA {
    String SomeString = "asd";
}

TestA testA = new TestA();
ObjectMapper om = new ObjectMapper();
try {
    String testAString = om.writeValueAsString(testA); // error here!

    TestA newTestA = om.readValue(testAString, TestA.class);
} catch (JsonGenerationException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (JsonMappingException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

当前回答

如果可以编辑包含该对象的类，我通常只添加注释

import com.fasterxml.jackson.annotation.JsonIgnore;

@JsonIgnore 
NonSerializeableClass obj;

2015-01-16 02:57:21

其他回答

Jackson要序列化该类，SomeString字段需要是公共的(目前它是包级隔离)，或者需要为它定义getter和setter方法。

2011-12-03 11:29:50

Jackson使用getter和setter序列化。/反序列化。所以在模型类中添加getter和setter。

2021-10-12 09:26:36

As already described, the default configuration of an ObjectMapper instance is to only access properties that are public fields or have public getters/setters. An alternative to changing the class definition to make a field public or to provide a public getter/setter is to specify (to the underlying VisibilityChecker) a different property visibility rule. Jackson 1.9 provides the ObjectMapper.setVisibility() convenience method for doing so. For the example in the original question, I'd likely configure this as

myObjectMapper.setVisibility(JsonMethod.FIELD, Visibility.ANY);

杰克逊>2.0:

myObjectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);

有关相关配置选项的更多信息和详细信息，我建议查看ObjectMapper.setVisibility()上的JavaDocs。

2011-12-06 05:53:26

SpringBoot2.0，我通过下面的代码来解决它:

@Bean public ObjectMapper objectMapper() {
 return new ObjectMapper().disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);}

2018-09-08 09:58:06

对于Oracle Java应用程序，在ObjectMapper实例化之后添加这个:

mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);

2016-11-24 22:06:12

序列化与杰克逊(JSON) -得到“没有发现序列化器”?

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