Java 解决；未找到合适的HttpMessageConverter“；错误

我有一个简单的应用程序正在尝试使用Rest服务：

@SpringBootApplication
public class ConsumingRestApplication
{

    private static final Logger log = LoggerFactory.getLogger(ConsumingRestApplication.class);

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

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder)
    {
        return builder.build();
    }

    @Bean
    public CommandLineRunner run(RestTemplate restTemplate) throws Exception
    {
        return args -> {
            try
            {
                restTemplate.getForObject("https://gturnquist-quoters.cfapps.io/api/random", Quote.class);
                
            } catch (RestClientException e)
            {
                e.printStackTrace();
            }
        };
    }
}

报价类别：

@JsonIgnoreProperties(ignoreUnknown = true)
public class Quote {

  private String type;
  private Value value;

  public Quote() {
  }

  public String getType() {
    return type;
  }

  public void setType(String type) {
    this.type = type;
  }

  public Value getValue() {
    return value;
  }

  public void setValue(Value value) {
    this.value = value;
  }

  @Override
  public String toString() {
    return "Quote{" +
        "type='" + type + '\'' +
        ", value=" + value +
        '}';
  }
}

出现错误：

org.springframework.web.client.UnknownContentTypeException: Could not extract response: no suitable HttpMessageConverter found for response type [class com.example.consumingrest.Quote] and content type [application/json;charset=UTF-8]

整个异常跟踪：

2020-10-19 12:39:04.984  INFO 8328 --- [  restartedMain] c.e.c.ConsumingRestApplication           : Starting ConsumingRestApplication on GM with PID 8328 (C:\gdrive\java_test\consumingrest\build\classes\java\main started by g in C:\gdrive\java_test\consumingrest)
2020-10-19 12:39:04.987  INFO 8328 --- [  restartedMain] c.e.c.ConsumingRestApplication           : No active profile set, falling back to default profiles: default
2020-10-19 12:39:05.070  INFO 8328 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2020-10-19 12:39:05.070  INFO 8328 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2020-10-19 12:39:06.843  INFO 8328 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2020-10-19 12:39:06.856  INFO 8328 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-10-19 12:39:06.857  INFO 8328 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.38]
2020-10-19 12:39:06.957  INFO 8328 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-10-19 12:39:06.957  INFO 8328 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1887 ms
2020-10-19 12:39:07.204  INFO 8328 --- [  restartedMain] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-10-19 12:39:07.395  INFO 8328 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2020-10-19 12:39:07.603  INFO 8328 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2020-10-19 12:39:07.617  INFO 8328 --- [  restartedMain] c.e.c.ConsumingRestApplication           : Started ConsumingRestApplication in 3.076 seconds (JVM running for 3.545)
2020-10-19 12:39:07.786  WARN 8328 --- [  restartedMain] .c.j.MappingJackson2HttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type, class com.example.consumingrest.Quote]]: com.fasterxml.jackson.databind.JsonMappingException: Cannot deserialize Class org.springframework.beans.factory.annotation.Value (of type annotation) as a Bean
2020-10-19 12:39:07.786  WARN 8328 --- [  restartedMain] .c.j.MappingJackson2HttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type, class com.example.consumingrest.Quote]]: com.fasterxml.jackson.databind.JsonMappingException: Cannot deserialize Class org.springframework.beans.factory.annotation.Value (of type annotation) as a Bean
2020-10-19 12:39:08.541  WARN 8328 --- [  restartedMain] .c.j.MappingJackson2HttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type, class com.example.consumingrest.Quote]]: com.fasterxml.jackson.databind.JsonMappingException: Cannot deserialize Class org.springframework.beans.factory.annotation.Value (of type annotation) as a Bean
2020-10-19 12:39:08.542  WARN 8328 --- [  restartedMain] .c.j.MappingJackson2HttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type, class com.example.consumingrest.Quote]]: com.fasterxml.jackson.databind.JsonMappingException: Cannot deserialize Class org.springframework.beans.factory.annotation.Value (of type annotation) as a Bean
2020-10-19 12:39:08.544  WARN 8328 --- [  restartedMain] .c.j.MappingJackson2HttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type, class com.example.consumingrest.Quote]]: com.fasterxml.jackson.databind.JsonMappingException: Cannot deserialize Class org.springframework.beans.factory.annotation.Value (of type annotation) as a Bean
2020-10-19 12:39:08.545  WARN 8328 --- [  restartedMain] .c.j.MappingJackson2HttpMessageConverter : Failed to evaluate Jackson deserialization for type [[simple type, class com.example.consumingrest.Quote]]: com.fasterxml.jackson.databind.JsonMappingException: Cannot deserialize Class org.springframework.beans.factory.annotation.Value (of type annotation) as a Bean
org.springframework.web.client.UnknownContentTypeException: Could not extract response: no suitable HttpMessageConverter found for response type [class com.example.consumingrest.Quote] and content type [application/json;charset=UTF-8]
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:126)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:741)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:674)
    at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:315)
    at com.example.consumingrest.ConsumingRestApplication.lambda$run$0(ConsumingRestApplication.java:37)
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:795)
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:779)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:322)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at com.example.consumingrest.ConsumingRestApplication.main(ConsumingRestApplication.java:21)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)

---

解决这个问题的出发点是什么？我应该用什么逻辑来查找问题？

我认为您缺少

值

对象，或者一定是错误的导入。此外，如果字段是私有的，则需要为其添加getter方法，当您直接在响应中返回该对象时，我是这样做的：

import org.springframework.beans.factory.annotation.Autowired；
导入org.springframework.boot.SpringApplication；
导入org.springframework.boot.autoconfigure.springboot应用程序；
导入org.springframework.boot.web.client.RestTemplateBuilder；
导入org.springframework.context.annotation.Bean；
导入org.springframework.web.bind.annotation.GetMapping；
导入org.springframework.web.bind.annotation.RestController；
导入org.springframework.web.client.rest模板；
@SpringBoot应用程序
公共类演示应用程序{
公共静态void main（字符串[]args）{
run（DemoApplication.class，args）；
}
@豆子
公共RestTemplate RestTemplate（RestTemplateBuilder）{
返回builder.build（）；
}
@RestController
公共静态类测试{
@自动连线
私有RestTemplate RestTemplate；
@GetMapping
公开报价测试（）{
返回restTemplate.getForObject（“https://gturnquist-quoters.cfapps.io/api/random“，Quote.class）；
}
}
公共静态类引用{
私有字符串类型；
私人价值；
公共字符串getType（）{
返回类型；
}
公共值getValue（）{
返回值；
}
}
公共静态类值{
私人长id；
私有字符串引用；
公共长getId（）{
返回id；
}
公共字符串getQuote（）{
返回报价；
}
}
}