java 在桌面应用程序中使用 RestTemplate 使用 Rest 服务时出现的问题
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Issue When Consume Rest Service with RestTemplate in Desktop App
提问by Deny Prasetyo
I have a problem when Consume Rest Service with RestTemplate in Desktop App whereas the problem doesn't appear when i use in Web app.
我在桌面应用程序中使用 RestTemplate 使用 Rest 服务时遇到问题，而当我在 Web 应用程序中使用时没有出现问题。
This Is the Debugging logs
这是调试日志
15:30:40.448 [main] DEBUG o.s.web.client.RestTemplate - Reading [java.util.List] as "application/json" using [org.springframework.http.converter.json.MappingHymansonHttpMessageConverter@98adae2]
15:30:40.452 [main] DEBUG httpclient.wire.content - << "[{"name":"Indonesia","id":1},{"name":"AlaySia","id":2},{"name":"Autraliya","id":3}]"
Exception in thread "main" java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.mgm.domain.Country
线程“main”中的异常 java.lang.ClassCastException：java.util.LinkedHashMap 无法转换为 com.mgm.domain.Country
And this is the Code that i use.
这是我使用的代码。
String url = "http://localhost:8080/mgm/country";
List<MediaType> mediaTypes = new ArrayList<MediaType>();
mediaTypes.add(MediaType.APPLICATION_JSON);
HttpHeaders headers = new HttpHeaders();
headers.setAccept(mediaTypes);
HttpEntity<Country> httpEntity = new HttpEntity<Country>(null, headers);
try {
ResponseEntity<List> responseEntity = restTemplate.exchange(url, HttpMethod.GET, httpEntity, List.class);
List<Country> countries = responseEntity.getBody();
System.out.println(countries.get(0).getName());
} catch (RestClientException exception) {
exception.printStackTrace();
}
Code above doesn't give errors when i place it in web app. I use Spring Rest MVC to Provide JSON and Consume it with RestTemplate.
当我将它放在网络应用程序中时，上面的代码不会出错。我使用 Spring Rest MVC 提供 JSON 并使用 RestTemplate 使用它。
I think there is a problem when Hymanson Convert java.util.LinkedHashMapto Country. it Seems that countries.get(0)actually has LinkedHashMaptype not Countryand problem will appeared when i invoke one of Countrymethode like .getName()
我认为 Hymanson 转换java.util.LinkedHashMap为Country. 似乎countries.get(0)实际上没有LinkedHashMap类型Country，当我调用其中一个Country方法时会出现问题.getName()
回答by stoffer
Try using an array instead:
尝试改用数组：
String url = "http://localhost:8080/mgm/country";
List<MediaType> mediaTypes = new ArrayList<MediaType>();
mediaTypes.add(MediaType.APPLICATION_JSON);
HttpHeaders headers = new HttpHeaders();
headers.setAccept(mediaTypes);
HttpEntity<Country> httpEntity = new HttpEntity<Country>(null, headers);
try {
ResponseEntity<Country[]> responseEntity = restTemplate.exchange(url, HttpMethod.GET, httpEntity, Country[].class);
Country[] countries = responseEntity.getBody();
System.out.println(countries[0].getName());
} catch (RestClientException exception) {
exception.printStackTrace();
}
