春季测试休息模板：无法提取响应：没有找到适合响应类型的 HttpMessageConverter答案

【问题标题】：spring test rest template : Could not extract response: no suitable HttpMessageConverter found for response type春季测试休息模板：无法提取响应：没有找到适合响应类型的 HttpMessageConverter
【发布时间】：2020-02-09 22:48:24
【问题描述】：

我得到了这个异常

org.springframework.web.client.RestClientException：无法提取响应：没有找到适合响应类型 [AnalyticsResponse] 和内容类型 [application/json;charset=UTF-8] 的 HttpMessageConverter

仅在我的 junit 测试用例中（Rest 端点工作正常）如果我的 DTO 包含 一个以用户定义的类作为键的映射

@Data
public class AnalyticsResponse {

    private List<Committer> commitersList; //OK
    private Map<Committer , Long> comittersCommitsMap; // Problem
    private Map<Date, List<CommitItem>> commitItemsTimeLineMap; //OK

}

如果 committersCommitsMap 字段被移除，一切都会正常

我的测试用例代码sn-p：

ResponseEntity<AnalyticsResponse> analyticsResponse = testRestTemplate.getForEntity(ANALYSIS_CONTROLLER_BASE_URL+"analytics?repo-full-name=" + searchResponse.getBody().get(0).getFull_name() ,
                AnalyticsResponse.class);

---更新：提交者类

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Committer {

    private  String name;
    private String email;

}

【问题讨论】：

标签： spring spring-mvc spring-test fasterxml

【解决方案1】：

默认情况下，ObjectMapper 无法确定Map 的序列化和反序列化，其中key 不是String，您必须提供自定义实现。

为Committer和Date实现KeyDeserializer和JsonSerializer（作为Map的键）

使用KeyDeserializer 和KeySerializer（JsonSerializer）配置ObjectMapper - register 模块

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    // KeyDeserializer for Committer (simple without 'null' check)
    @RequiredArgsConstructor
    public static class CommitterKeyDeserializer extends KeyDeserializer {

        private final ObjectMapper mapper;

        @Override
        public Object deserializeKey(final String key,
                                     final DeserializationContext ctxt)
                throws IOException, JsonProcessingException {

            return mapper.readValue(key, Committer.class);
        }
    }

    // KeyDeserializer for Date (simple without 'null' check)
    @RequiredArgsConstructor
    public static class DateKeyDeserializer extends KeyDeserializer {

        private final ObjectMapper mapper;

        @Override
        public Object deserializeKey(final String key,
                                     final DeserializationContext ctxt)
                throws IOException, JsonProcessingException {

            return mapper.readValue(key, Date.class);
        }
    }

    // JsonSerializer for Committer (simple without 'null' check)
    @RequiredArgsConstructor
    public static class CommitterJsonSerializer extends JsonSerializer<Committer> {

        private final ObjectMapper mapper;

        @Override
        public void serialize(Committer committer,
                              JsonGenerator jgen,
                              SerializerProvider provider)
                throws IOException, JsonProcessingException {

            jgen.writeFieldName(mapper.writeValueAsString(committer));
        }

    }

    // JsonSerializer for Date (simple without 'null' check)
    public static class DateJsonSerializer extends JsonSerializer<Date> {

        @Override
        public void serialize(Date date,
                              JsonGenerator jgen,
                              SerializerProvider provider)
                throws IOException, JsonProcessingException {

            jgen.writeFieldName(String.valueOf(date.getTime()));
        }

    }

    // ObjectMapper configuration
    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();

        // register module with custom serializers and deserializers
        mapper.registerModule(new SimpleModule()
                .addKeyDeserializer(
                        Committer.class,
                        new CommitterKeyDeserializer(mapper))
                .addKeyDeserializer(
                        Date.class,
                        new DateKeyDeserializer(mapper))
                .addKeySerializer(
                        Committer.class,
                        new CommitterJsonSerializer(mapper))
                .addKeySerializer(
                        Date.class,
                        new DateJsonSerializer()));

        return mapper;
    }

    // RestTemplate configuration
    @Bean
    public RestTemplate restTemplate(List<HttpMessageConverter<?>> converters) {
        RestTemplate restTemplate = new RestTemplate();
        // add spring's predefined converters
        restTemplate.setMessageConverters(converters);

        return restTemplate;
    }

}

请注意，在这个简单的实现中，comittersCommitsMap 中的 key Committer 在 JSON 响应中表示为 String（RestTemplate 与此实现同样有效）：

{
    "commitersList": [
        {
            "name": "name",
            "email": "email"
        }
    ],
    "comittersCommitsMap": {
        "{\"name\":\"name\",\"email\":\"email\"}": 1
    },
    "commitItemsTimeLineMap": {
        "1570929503854": [
            {
                "data": "data"
            }
        ]
    }
}

【讨论】：