Spring 假装 : Could not extract response: no suitable HttpMessageConverter found for response type

Question

我想得到一个 Spring Cloud Netflix Feign客户端通过 HTTP 获取一些 JSON 并将其转换为对象。我不断收到此错误:

org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class io.urig.checkout.Book] and content type [application/json;charset=UTF-8]

这是从远程服务返回的 JSON 部分:

{
    "id": 1,
    "title": "Moby Dick",
    "author": "Herman Melville"
}

这是我尝试反序列化的相应类:

package io.urig.checkout;

public class Book {
    private long id;
    private String title;
    private String author;

    public Book() {}

    public Book(long id, String title, String author) {
        super();
        this.id = id;
        this.title = title;
        this.author = author;
    }

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getAuthor() {
        return author;
    }
    public void setAuthor(String author) {
        this.author = author;
    }
}

这是我的 Feign 客户端:

package io.urig.checkout;

import java.util.Optional;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import io.urig.checkout.Book;

@FeignClient(name="inventory", url="http://localhost:8080/")
public interface InventoryClient {

    @RequestMapping(method = RequestMethod.GET, value = "books/{bookId}")
    public Optional<Book> getBookById(@PathVariable(value="bookId") Long bookId);

}

我需要做什么才能让它发挥作用？

Answer 1

我不知道 Feign，但是当我过去出现“找不到合适的 HttpMessageConverter...”错误时，这是​​因为尚未注册内容类型。也许您需要将其添加到 RequestMapping 中:

consumes = "application/json"

我只能建议尝试确认 Feign 配置是否将 MappingJackson2HttpMessageConverter 注册为 Book 的转换器。不确定这是否应该与 Feign 一起开箱即用，或者您是否必须手动完成。我在 Feign 的 GitHub 上看到一个例子，它有:

GitHub github = Feign.builder()
                 .encoder(new JacksonEncoder())
                 .decoder(new JacksonDecoder())
                 .target(GitHub.class, "https://api.github.com");

您是否使用 Feign.builder() 或一些等效的配置文件创建了配置？