如何用java中的jackson将json反序列化为enum？

我有一个与名称字段的接口，如下所示：

public interface Field {
}

public enum BField implements Field {
    SOME_FIELD
}

public class C implements Serializable {
    private Set<Field> f;

    public Set<Field> getF() { return f; }
    public void setF(Set<Field> f) { this f = f; }
}

@RequestMapping(method=RequestMethod.Post, value="/save")
@ResponseBody
public void save (@RequestBody C c) {
    //save c
}

public class JsonBFieldDeserializer extends StdDeserializer<Field> {
    public JsonBFieldDeserializer() {
        this(null);
    }
    public JsonBFieldDeserializer(Class<?> vc) {
        super(vc);
    }
    @Overrid
    public Field deserialize(JsonParser jsonParser, DeserializationContext dC) throws IOException, JsonProcessingException {
        JsonNode node = jsonParser.getCodec().readTree();
        String text = node.asText();
        return BField.valueOf(text);
    }
}

@Configuration
public class BConfiguration extends WebMVCConfigurationSupport {
    protected void configureMessageConverters(List<HttpMessageConverters<?>> converters){
        converters.add(convert());
        addDefaultHttpMessageConverters(converters);
    }
    @Bean
    MappingJackson2HttpMessageConverter convert(){
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addDeserializer(Field.class, new JsonBFieldDeserializer());
        objectMapper.registerModule(module);
        converter.setObjectMapper(objectMapper);
        return converter;
    }
}

此接口位于模块A中。 我有一个名为BField的枚举，它位于模块B中，实现如下：

public interface Field {
}

public enum BField implements Field {
    SOME_FIELD
}

public class C implements Serializable {
    private Set<Field> f;

    public Set<Field> getF() { return f; }
    public void setF(Set<Field> f) { this f = f; }
}

@RequestMapping(method=RequestMethod.Post, value="/save")
@ResponseBody
public void save (@RequestBody C c) {
    //save c
}

public class JsonBFieldDeserializer extends StdDeserializer<Field> {
    public JsonBFieldDeserializer() {
        this(null);
    }
    public JsonBFieldDeserializer(Class<?> vc) {
        super(vc);
    }
    @Overrid
    public Field deserialize(JsonParser jsonParser, DeserializationContext dC) throws IOException, JsonProcessingException {
        JsonNode node = jsonParser.getCodec().readTree();
        String text = node.asText();
        return BField.valueOf(text);
    }
}

@Configuration
public class BConfiguration extends WebMVCConfigurationSupport {
    protected void configureMessageConverters(List<HttpMessageConverters<?>> converters){
        converters.add(convert());
        addDefaultHttpMessageConverters(converters);
    }
    @Bean
    MappingJackson2HttpMessageConverter convert(){
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addDeserializer(Field.class, new JsonBFieldDeserializer());
        objectMapper.registerModule(module);
        converter.setObjectMapper(objectMapper);
        return converter;
    }
}

模块a中有一个名为C的类，如下所示：

public interface Field {
}

public enum BField implements Field {
    SOME_FIELD
}

public class C implements Serializable {
    private Set<Field> f;

    public Set<Field> getF() { return f; }
    public void setF(Set<Field> f) { this f = f; }
}

@RequestMapping(method=RequestMethod.Post, value="/save")
@ResponseBody
public void save (@RequestBody C c) {
    //save c
}

public class JsonBFieldDeserializer extends StdDeserializer<Field> {
    public JsonBFieldDeserializer() {
        this(null);
    }
    public JsonBFieldDeserializer(Class<?> vc) {
        super(vc);
    }
    @Overrid
    public Field deserialize(JsonParser jsonParser, DeserializationContext dC) throws IOException, JsonProcessingException {
        JsonNode node = jsonParser.getCodec().readTree();
        String text = node.asText();
        return BField.valueOf(text);
    }
}

@Configuration
public class BConfiguration extends WebMVCConfigurationSupport {
    protected void configureMessageConverters(List<HttpMessageConverters<?>> converters){
        converters.add(convert());
        addDefaultHttpMessageConverters(converters);
    }
    @Bean
    MappingJackson2HttpMessageConverter convert(){
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addDeserializer(Field.class, new JsonBFieldDeserializer());
        objectMapper.registerModule(module);
        converter.setObjectMapper(objectMapper);
        return converter;
    }
}

我将此JSON对象发送到此方法：

{
    "f": ["SOME_FIELD"]
}

然后，我得到HTTP 400错误请求错误代码和以下异常日志：

抽象类型只能用其他类型实例化 信息

---

模块的层次结构为模块B依赖于模块A。我试图使用@JsonTypeInfo，但模块之间的依赖关系是一个限制，不允许我在@JsonSubTypes注释中为类C中的字段f使用BField.class。

这里的问题不是

枚举

，而是

集合

和

字段

接口

您需要告诉Jackson您想要什么类型的

集合

和什么类型的

字段

，您可以通过以下方式注释该属性：

@JsonDeserialize(as = EnumSet.class, contentAs = BField.class)

---

最后我找到了解决办法

我在上下文中删除

为字段

私有集f添加
@JsonDeserialize（as=EnumSet.class）
注释在C类中

在模块B中创建一个名为JsonBFieldDeserializer的类，如下所示：

public interface Field {
}

public enum BField implements Field {
    SOME_FIELD
}

public class C implements Serializable {
    private Set<Field> f;

    public Set<Field> getF() { return f; }
    public void setF(Set<Field> f) { this f = f; }
}

@RequestMapping(method=RequestMethod.Post, value="/save")
@ResponseBody
public void save (@RequestBody C c) {
    //save c
}

public class JsonBFieldDeserializer extends StdDeserializer<Field> {
    public JsonBFieldDeserializer() {
        this(null);
    }
    public JsonBFieldDeserializer(Class<?> vc) {
        super(vc);
    }
    @Overrid
    public Field deserialize(JsonParser jsonParser, DeserializationContext dC) throws IOException, JsonProcessingException {
        JsonNode node = jsonParser.getCodec().readTree();
        String text = node.asText();
        return BField.valueOf(text);
    }
}

@Configuration
public class BConfiguration extends WebMVCConfigurationSupport {
    protected void configureMessageConverters(List<HttpMessageConverters<?>> converters){
        converters.add(convert());
        addDefaultHttpMessageConverters(converters);
    }
    @Bean
    MappingJackson2HttpMessageConverter convert(){
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addDeserializer(Field.class, new JsonBFieldDeserializer());
        objectMapper.registerModule(module);
        converter.setObjectMapper(objectMapper);
        return converter;
    }
}

公共类JsonBFieldDeserializer扩展了StdDeserializer{
公共JsonBFieldDeserializer（）{
这个（空）；
}
公共JsonBFieldDeserializer（类vc）{
超级（vc）；
}
@凌驾
公共字段反序列化（JsonParser、JsonParser、反序列化上下文dC）引发IOException、JsonProcessingException{
JsonNode节点=jsonParser.getCodec（）.readTree（）；
String text=node.asText（）；
返回BField.valueOf（文本）；
}
}

在模块B中创建一个名为BConfiguration的类，如下所示：

public interface Field {
}

public enum BField implements Field {
    SOME_FIELD
}

public class C implements Serializable {
    private Set<Field> f;

    public Set<Field> getF() { return f; }
    public void setF(Set<Field> f) { this f = f; }
}

@RequestMapping(method=RequestMethod.Post, value="/save")
@ResponseBody
public void save (@RequestBody C c) {
    //save c
}

public class JsonBFieldDeserializer extends StdDeserializer<Field> {
    public JsonBFieldDeserializer() {
        this(null);
    }
    public JsonBFieldDeserializer(Class<?> vc) {
        super(vc);
    }
    @Overrid
    public Field deserialize(JsonParser jsonParser, DeserializationContext dC) throws IOException, JsonProcessingException {
        JsonNode node = jsonParser.getCodec().readTree();
        String text = node.asText();
        return BField.valueOf(text);
    }
}

@Configuration
public class BConfiguration extends WebMVCConfigurationSupport {
    protected void configureMessageConverters(List<HttpMessageConverters<?>> converters){
        converters.add(convert());
        addDefaultHttpMessageConverters(converters);
    }
    @Bean
    MappingJackson2HttpMessageConverter convert(){
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addDeserializer(Field.class, new JsonBFieldDeserializer());
        objectMapper.registerModule(module);
        converter.setObjectMapper(objectMapper);
        return converter;
    }
}

@配置
公共类B配置扩展了WebMVCConfigurationSupport{
受保护的无效配置MessageConverters（ListXcuse我忘了注意接口字段有多个实现。例如模块B中的BField和模块D中的DField。谢谢。当我只使用接口字段的一个实现来测试它时，您的解决方案是有效的，但我也必须依赖模块A到模块B。我的问题有点不同。首先，我不想依赖模块A到模块B，第二个接口字段在多个模块中有多个实现。只有从模块中收集Jackson片段并将其聚合，您才可能需要它；一个示例是Druid如何允许您注册自定义解析器和其他内容：