Spring 弹簧不'；不使用RESTful Web服务，但正确地反序列化相应的字符串，为什么？

我试图使用

Spring

使用

restfulweb服务

，我的参考代码就是其中的一个。我询问的服务返回

JSON

，如下所示：

{ "id": 1,
  "content": [
    { "dependencies": [
      { "parent": 0, "child": 1, "type": "PUNCT" },
      { "parent": 0, "child": 2, "type": "NPADVMOD" },
      { "parent": 0, "child": 3, "type": "PUNCT" } ], 
      "tokens": [
      { "ent": "", "index": 0, "lemma": "hello", "pos": "INTJ", "tag": "UH", "text": "Hello" },
      { "ent": "", "index": 1, "lemma": ",", "pos": "PUNCT", "tag": ",", "text": "," },
      { "ent": "PERSON", "index": 2, "lemma": "world", "pos": "PROPN", "tag": "NNP", "text": "World" },
      { "ent": "", "index": 3, "lemma": "!", "pos": "PUNCT", "tag": ".", "text": "!" } ]
    } ]
}

我创建了以下对象（为了简洁起见，省略了它们的所有方法）：

正如我在日志中看到的：

17:26:34.609 [qtp990226843-17] INFO a.c.j.controllers.ExampleController - Message[content = [Content[dependencies = [Dependency[child = 1, parent = 0, type = PUNCT], Dependency[child = 2, parent = 0, type = NPADVMOD], Dependency[child = 3, parent = 0, type = PUNCT]], tokens = [Token[ent = , index = 0, lemma = hello, pos = INTJ, tag = UH, text = Hello], Token[ent = , index = 1, lemma = ,, pos = PUNCT, tag = ,, text = ,], Token[ent = PERSON, index = 2, lemma = world, pos = PROPN, tag = NNP, text = World], Token[ent = , index = 3, lemma = !, pos = PUNCT, tag = ., text = !]]]], id = 1]

如果我尝试使用以下代码直接连接到RESTful Web服务：

@RequestMapping("/remote")
public Boolean remote() {
    RestTemplate restTemplate = new RestTemplate();

    Map<String, String> env = System.getenv();
    String host = env.getOrDefault("MY_HOST", "localhost");
    String port = env.getOrDefault("MY_HOST", "7890");
    String url = String.format("http://%s:%s", host, port);

    String content = "Hello, World!";

    URI uri = UriComponentsBuilder.fromHttpUrl(url).queryParam("content", content).build().encode().toUri();
    Message response = REST_TEMPLATE.getForObject(uri, Message.class);
    logger.info("I got: {}", response);

    return Boolean.TRUE;
}

我在网上搜索，在这个网站上寻找解决方案，但我想不出任何关键字，导致有意义的结果。。。有什么帮助吗

为什么会出现此错误？如何修复它？

谢谢

PS：我刚刚尝试实现一个

哑服务

，它连接到

远程服务

，并将该服务接收到的JSON作为字符串返回，我修改了

解码服务

，该服务已经能够对JSON进行反序列化，从而从

哑服务

而不是

远程服务

获取数据，而且它工作正常！我大吃一惊！这没有道理！ 无论如何，代码如下（请告诉我是否可以避免使用

哑服务

）：

@RequestMapping（“/dumb”）
公共字符串dumb（）{
Map env=System.getenv（）；
字符串host=env.getOrDefault（“SPACY_主机”、“本地主机”）；
String port=env.getOrDefault（“SPACY_主机”、“7890”）；
字符串url=String.format（“http://%s:%s”、主机、端口）；
String content=“你好，世界！”；
URI URI=UriComponentsBuilder.fromHttpUrl（url）.queryParam（“content”，content.build（）.encode（）.tori（）；
RestTemplate RestTemplate=新RestTemplate（）；
String response=restTemplate.getForObject（uri，String.class）；
info（“我得到：{}”，响应）；
返回响应；
}
@请求映射（“/decode”）
公共布尔解码（）{
RestTemplate RestTemplate=新RestTemplate（）；
消息响应=restTemplate.getForObject（“http://localhost:8080/dumb“，Message.class）；
info（“我得到：{}”，响应）；
返回Boolean.TRUE；
}

将RestTemplate注入控制器，不要为每个请求创建RestTemplate。问题是您的RestTemplate实例中没有注册的消息转换器。请提供一些代码好吗？我试图扩展这个例子，但没有成功。。。非常感谢。

17:26:34.609 [qtp990226843-17] INFO a.c.j.controllers.ExampleController - Message[content = [Content[dependencies = [Dependency[child = 1, parent = 0, type = PUNCT], Dependency[child = 2, parent = 0, type = NPADVMOD], Dependency[child = 3, parent = 0, type = PUNCT]], tokens = [Token[ent = , index = 0, lemma = hello, pos = INTJ, tag = UH, text = Hello], Token[ent = , index = 1, lemma = ,, pos = PUNCT, tag = ,, text = ,], Token[ent = PERSON, index = 2, lemma = world, pos = PROPN, tag = NNP, text = World], Token[ent = , index = 3, lemma = !, pos = PUNCT, tag = ., text = !]]]], id = 1]

@RequestMapping("/remote")
public Boolean remote() {
    RestTemplate restTemplate = new RestTemplate();

    Map<String, String> env = System.getenv();
    String host = env.getOrDefault("MY_HOST", "localhost");
    String port = env.getOrDefault("MY_HOST", "7890");
    String url = String.format("http://%s:%s", host, port);

    String content = "Hello, World!";

    URI uri = UriComponentsBuilder.fromHttpUrl(url).queryParam("content", content).build().encode().toUri();
    Message response = REST_TEMPLATE.getForObject(uri, Message.class);
    logger.info("I got: {}", response);

    return Boolean.TRUE;
}

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Fri Jun 02 16:53:42 BST 2017
There was an unexpected error (type=Internal Server Error, status=500).
org.springframework.web.util.NestedServletException: Request processing failed; 
nested exception is org.springframework.web.client.RestClientException: 
Could not extract response: no suitable HttpMessageConverter found for response 
type [class ai.context_scout.joshi.model.Message] and content type 
[text/plain;charset=utf-8]

@RequestMapping("/dumb")
public String dumb() {
    Map<String, String> env = System.getenv();
    String host = env.getOrDefault("SPACY_HOST", "localhost");
    String port = env.getOrDefault("SPACY_HOST", "7890");
    String url = String.format("http://%s:%s", host, port);

    String content = "Hello, World!";

    URI uri = UriComponentsBuilder.fromHttpUrl(url).queryParam("content", content).build().encode().toUri();

    RestTemplate restTemplate = new RestTemplate();

    String response = restTemplate.getForObject(uri, String.class);
    logger.info("I got: {}", response);

    return response;
}

@RequestMapping("/decode")
public Boolean decode() {
    RestTemplate restTemplate = new RestTemplate();

    Message response = restTemplate.getForObject("http://localhost:8080/dumb", Message.class);
    logger.info("I got: {}", response);

    return Boolean.TRUE;
}