Java 克服；无法构造InterfaceClass的实例“；没有暗示父母

我的控制器中有此方法：

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {

    // Do something
}

我得到的错误非常直截了当且不言自明：

Can not construct instance of InterfaceClass: abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information.

基本上，我需要告诉Spring我有一个

InterfaceClass

，

ClassImpl

的具体实现

我试过：

@JsonRootName("InterfaceClass")
public class ClassImpl implements InterfaceClass {
}

毫无疑问。我不能使用

@JsonTypeInfo

，因为父接口类

InterfaceClass

不应该知道

ClassImpl

，它们在不同的模块中。我也尝试过：

使用abstract

AbstractClass

实现

InterfaceClass

，并放置：

@JsonDeserialize(as = AbstractClass.class)

在

接口类的顶部

。然后使用

ClassImpl

扩展

AbstractClass

。错误只会变成：

Can not construct instance of InterfaceClass: abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information.

进一步审判：

public class ControllerClass<E extends InterfaceClass> {

    @RequestMapping(method = RequestMethod.POST)
    InterfaceClass insert(@RequestBody E interfaceClass) {
        InterfaceClass object = (InterfaceClass) interfaceClass;
    }
}

正如所料

我真的很期待Spring Boot处理组件发现，因为

InterfaceClass

或

AbstractClass

只有一个具体的实现，那就是我的类路径中的

ClassImpl

。也许我做错了什么？我如何克服这一问题，而不显式地暗示

接口类

其实现的位置（例如，no

@JsonDeserialize

等）？

解决方案1-动态注册子类型 可以动态定义子类型

1。在接口上，定义一个JSON字段（@type）用作标识符：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

2。将“@type”字段添加到JSON有效负载中

{
    ...
    "@type": "someName"
}

2。动态注册接口的子类型：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

4。在具体类上指定“@type”名称（可选）：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

5。Use现在可以使用@RequestBody:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

---

解决方案2-动态注册自定义反序列化程序 如果无法（或不需要）添加

@type

字段，您还可以为接口定义自定义反序列化程序，这实际上会创建

ClassImpl

：

1。定义自定义反序列化程序：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

3。从接口中删除@JsonTypeInfo:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

解决方案1-动态注册子类型 可以动态定义子类型

1。在接口上，定义一个JSON字段（@type）用作标识符：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

2。将“@type”字段添加到JSON有效负载中

{
    ...
    "@type": "someName"
}

2。动态注册接口的子类型：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

4。在具体类上指定“@type”名称（可选）：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

5。Use现在可以使用@RequestBody:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

---

解决方案2-动态注册自定义反序列化程序 如果无法（或不需要）添加

@type

字段，您还可以为接口定义自定义反序列化程序，这实际上会创建

ClassImpl

：

1。定义自定义反序列化程序：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}

3。从接口中删除@JsonTypeInfo:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, 
              include = JsonTypeInfo.As.PROPERTY, property = "@type")
public interface InterfaceClass {
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder() {
        public void configure(ObjectMapper objectMapper) {
            objectMapper.registerSubtypes(ClassImpl.class);
            super.configure(objectMapper);
        };
    };
    return builder;
}

//Optional, otherwise uses the Simple class name (ie: 'ClassImpl')
@JsonTypeName("someName") 
public class ClassImpl implements InterfaceClass {
}

@RequestMapping(method = RequestMethod.POST)
InterfaceClass insert(@RequestBody InterfaceClass interfaceClass) {
}

class ClassImplJsonDeserializer extends JsonDeserializer<ClassImpl> {
    @Override
    public ClassImpl deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        return jp.readValuesAs(ClassImpl.class).next();
    }
}

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.deserializerByType(InterfaceClass.class, new ClassImplJsonDeserializer());
    return builder;
}

public interface InterfaceClass {
}