自定义 Jackson HttpMessageConverter 在 Spring 4.2 中不再有效

json java spring-mvc jackson

2022-09-04 21:36:47

我正在将Spring Platform版本1.1.3.RELEASE更新到2.0.1.RELEASE，它将Spring Framework版本从4.1.7升级到4.2.4，Jackson从2.4.6升级到2.6.4。在Spring或Jackson对自定义实现的处理中似乎没有任何重大变化，但我的自定义JSON序列化未能发生，我无法确定原因。以下内容在以前的Spring Platform版本中工作正常：HttpMessageConverter

型

@JsonFilter("fieldFilter")
public class MyModel { 
    /*model fields and methods*/ 
}

模型包装器

public class ResponseEnvelope {

    private Set<String> fieldSet;
    private Set<String> exclude;
    private Object entity;

    public ResponseEnvelope(Object entity) {
        this.entity = entity;
    }

    public ResponseEnvelope(Object entity, Set<String> fieldSet, Set<String> exclude) {
        this.fieldSet = fieldSet;
        this.exclude = exclude;
        this.entity = entity;
    }

    public Object getEntity() {
        return entity;
    }

    @JsonIgnore
    public Set<String> getFieldSet() {
        return fieldSet;
    }

    @JsonIgnore
    public Set<String> getExclude() {
        return exclude;
    }

    public void setExclude(Set<String> exclude) {
        this.exclude = exclude;
    }

    public void setFieldSet(Set<String> fieldSet) {
        this.fieldSet = fieldSet;
    }

    public void setFields(String fields) {
        Set<String> fieldSet = new HashSet<String>();
        if (fields != null) {
            for (String field : fields.split(",")) {
                fieldSet.add(field);
            }
        }
        this.fieldSet = fieldSet;
    }
}

控制器

@Controller
public class MyModelController {

    @Autowired MyModelRepository myModelRepository;

    @RequestMapping(value = "/model", method = RequestMethod.GET, produces = { MediaType.APPLICATION_JSON_VALUE })
    public HttpEntity find(@RequestParam(required=false) Set<String> fields, @RequestParam(required=false) Set<String> exclude){
        List<MyModel> objects = myModelRepository.findAll();
        ResponseEnvelope envelope = new ResponseEnvelope(objects, fields, exclude);
        return new ResponseEntity<>(envelope, HttpStatus.OK);
    }
}

自定义 HttpMessageConverter

public class FilteringJackson2HttpMessageConverter extends MappingJackson2HttpMessageConverter {

    private boolean prefixJson = false;

    @Override
    public void setPrefixJson(boolean prefixJson) {
        this.prefixJson = prefixJson;
        super.setPrefixJson(prefixJson);
    }

    @Override
    protected void writeInternal(Object object, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {

        ObjectMapper objectMapper = getObjectMapper();
        JsonGenerator jsonGenerator = objectMapper.getFactory().createGenerator(outputMessage.getBody());

        try {

            if (this.prefixJson) {
                jsonGenerator.writeRaw(")]}', ");
            }

            if (object instanceof ResponseEnvelope) {

                ResponseEnvelope envelope = (ResponseEnvelope) object;
                Object entity = envelope.getEntity();
                Set<String> fieldSet = envelope.getFieldSet();
                Set<String> exclude = envelope.getExclude();
                FilterProvider filters = null;

                if (fieldSet != null && !fieldSet.isEmpty()) {
                    filters = new SimpleFilterProvider()
                            .addFilter("fieldFilter", SimpleBeanPropertyFilter.filterOutAllExcept(fieldSet))
                                .setFailOnUnknownId(false);
                } else if (exclude != null && !exclude.isEmpty()) {
                    filters = new SimpleFilterProvider()
                            .addFilter("fieldFilter", SimpleBeanPropertyFilter.serializeAllExcept(exclude))
                                .setFailOnUnknownId(false);
                } else {
                    filters = new SimpleFilterProvider()
                            .addFilter("fieldFilter", SimpleBeanPropertyFilter.serializeAllExcept())
                                .setFailOnUnknownId(false);
                }

                objectMapper.setFilterProvider(filters);
                objectMapper.writeValue(jsonGenerator, entity);

            } else if (object == null){
                jsonGenerator.writeNull();
            } else {
                FilterProvider filters = new SimpleFilterProvider().setFailOnUnknownId(false);
                objectMapper.setFilterProvider(filters);
                objectMapper.writeValue(jsonGenerator, object);
            }

        } catch (JsonProcessingException e){
            e.printStackTrace();
            throw new HttpMessageNotWritableException("Could not write JSON: " + e.getMessage());
        }

    }
}

配置

@Configuration
@EnableWebMvc
public class WebServicesConfig extends WebMvcConfigurerAdapter {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FilteringJackson2HttpMessageConverter jsonConverter = new FilteringJackson2HttpMessageConverter();
        jsonConverter.setSupportedMediaTypes(MediaTypes.APPLICATION_JSON);
        converters.add(jsonConverter);
    }

    // Other configurations
}

现在我得到这个异常（被Spring捕获并记录）和500错误，当提出任何类型的请求时：

[main] WARN  o.s.w.s.m.s.DefaultHandlerExceptionResolver - Failed to write HTTP message: 
  org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: 
  Can not resolve PropertyFilter with id 'fieldFilter'; 
  no FilterProvider configured (through reference chain:
  org.oncoblocks.centromere.web.controller.ResponseEnvelope["entity"]->java.util.ArrayList[0]); 
  nested exception is com.fasterxml.jackson.databind.JsonMappingException: 
  Can not resolve PropertyFilter with id 'fieldFilter'; 
  no FilterProvider configured (through reference chain: 
  org.oncoblocks.centromere.web.controller.ResponseEnvelope["entity"]->java.util.ArrayList[0])

该方法执行，但它看起来不像在请求期间使用过自定义转换器。是否有可能另一个消息转换器阻止此消息转换器到达我的响应？我的理解是，覆盖将阻止使用手动注册的转换器以外的转换器。configureMessageConvertersconfigureMessageConverters

除了通过Spring平台更新依赖项版本外，此代码的工作版本和非工作版本之间没有进行任何更改。JSON 序列化中是否有任何更改，我只是在文档中缺少这些更改？

编辑

进一步的测试会产生奇怪的结果。我想测试以检查以下内容：

我的自定义是否实际已注册？HttpMessageConverter
另一个转换器是否覆盖/取代了它？
这是否仅与我的测试设置有关？

因此，我添加了一个额外的测试并查看了输出：

@Autowired WebApplicationContext webApplicationContext;

@Before
public void setup(){
    mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
}

@Test
public void test() throws Exception {
    RequestMappingHandlerAdapter adapter = (RequestMappingHandlerAdapter) webApplicationContext.getBean("requestMappingHandlerAdapter");
    List<EntrezGene> genes = EntrezGene.createDummyData();
    Set<String> exclude = new HashSet<>();
    exclude.add("entrezGeneId");
    ResponseEnvelope envelope = new ResponseEnvelope(genes, new HashSet<String>(), exclude);
    for (HttpMessageConverter converter: adapter.getMessageConverters()){
        System.out.println(converter.getClass().getName());
        if (converter.canWrite(ResponseEnvelope.class, MediaType.APPLICATION_JSON)){
            MockHttpOutputMessage message =  new MockHttpOutputMessage();
            converter.write((Object) envelope, MediaType.APPLICATION_JSON, message);    
            System.out.println(message.getBodyAsString());
        }
    }
}

...它工作正常。我的对象及其内容已正确序列化和筛选。因此，要么请求处理在到达消息转换器之前存在问题，要么在测试请求的方式上发生了变化。envelopeMockMvc

答案 1

您的配置正常。未从自定义转换器调用的原因是因为您重写了错误的方法。writeInternal()

查看的源代码4.2.4.RELEASE

摘要MessageConverterMethodProcessor#writeWithMessageConverters

protected <T> void writeWithMessageConverters(T returnValue, MethodParameter returnType,
            ServletServerHttpRequest inputMessage, ServletServerHttpResponse outputMessage)
            throws IOException, HttpMediaTypeNotAcceptableException, HttpMessageNotWritableException {
    ...
    ((GenericHttpMessageConverter<T>) messageConverter).write(returnValue, returnValueType, selectedMediaType, outputMessage);
    ...
}

摘要GenericHttpMessageConverter#write

public final void write(final T t, final Type type, MediaType contentType, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {
    ...
    writeInternal(t, type, outputMessage);
    ...
}

从内部调用的方法有三个参数 - 。您正在覆盖只有 2 个参数的重载版本 - 。writeInternal(...)AbstractGenericHttpMessageConverter#write(...)(T t, Type type, HttpOutputMessage outputMessage)writeInternal(...)(T t, HttpOutputMessage outputMessage)

但是，在版本，事实并非如此，因此是问题的根本原因。此版本中使用的是您重写的另一个重载方法（具有 2 个参数的方法）。这就解释了为什么它在中工作正常。4.1.7.RELEASEwriteInternal(...)4.1.7.RELEASE

@Override
public final void write(final T t, MediaType contentType, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {
    ...
    writeInternal(t, outputMessage);
    ...
}

因此，要解决您的问题，而不是覆盖，覆盖writeInternal(Object object, HttpOutputMessage outputMessage)writeInternal(Object object, Type type, HttpOutputMessage outputMessage)

答案 2