uriVariables也在查询字符串中展开。例如，下面的调用将展开account和name的值:

restTemplate.exchange("http://my-rest-url.org/rest/account/{account}?name={name}",
    HttpMethod.GET,
    httpEntity,
    clazz,
    "my-account",
    "my-name"
);

实际的请求url是

http://my-rest-url.org/rest/account/my-account?name=my-name

查看HierarchicalUriComponents.expandInternal(UriTemplateVariables)了解更多细节。 Spring的版本是3.1.3。

我真是个白痴，我把查询参数和url参数搞混了。我有点希望有一个更好的方式来填充我的查询参数，而不是一个丑陋的连接字符串，但我们有。这只是一个用正确的参数构建URL的例子。如果你把它作为一个字符串传递，Spring也会为你处理编码。

为了方便地操作URL / path / params /等等，您可以使用Spring的UriComponentsBuilder类创建一个URL模板，其中包含参数占位符，然后在RestOperations.exchange(…)调用中提供这些参数的值。它比手动连接字符串更干净，它会为你处理URL编码:

HttpHeaders headers = new HttpHeaders();
headers.set(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_VALUE);
HttpEntity<?> entity = new HttpEntity<>(headers);

String urlTemplate = UriComponentsBuilder.fromHttpUrl(url)
        .queryParam("msisdn", "{msisdn}")
        .queryParam("email", "{email}")
        .queryParam("clientVersion", "{clientVersion}")
        .queryParam("clientType", "{clientType}")
        .queryParam("issuerName", "{issuerName}")
        .queryParam("applicationName", "{applicationName}")
        .encode()
        .toUriString();

Map<String, ?> params = new HashMap<>();
params.put("msisdn", msisdn);
params.put("email", email);
params.put("clientVersion", clientVersion);
params.put("clientType", clientType);
params.put("issuerName", issuerName);
params.put("applicationName", applicationName);

HttpEntity<String> response = restOperations.exchange(
        urlTemplate,
        HttpMethod.GET,
        entity,
        String.class,
        params
);

如果您为RestTemplate传递非参数参数，那么考虑到参数，您将为传递的每个不同URL都有一个Metrics。你想要使用参数化url:

http://my-url/action?param1={param1}&param2={param2}

而不是

http://my-url/action?param1=XXXX&param2=YYYY

第二种情况是使用UriComponentsBuilder类得到的结果。

实现第一个行为的方法如下:

Map<String, Object> params = new HashMap<>();
params.put("param1", "XXXX");
params.put("param2", "YYYY");

String url = "http://my-url/action?%s";

String parametrizedArgs = params.keySet().stream().map(k ->
    String.format("%s={%s}", k, k)
).collect(Collectors.joining("&"));

HttpHeaders headers = new HttpHeaders();
headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);
HttpEntity<String> entity = new HttpEntity<>(headers);

restTemplate.exchange(String.format(url, parametrizedArgs), HttpMethod.GET, entity, String.class, params);

    String uri = http://my-rest-url.org/rest/account/{account};

    Map<String, String> uriParam = new HashMap<>();
    uriParam.put("account", "my_account");

    UriComponents builder = UriComponentsBuilder.fromHttpUrl(uri)
                .queryParam("pageSize","2")
                        .queryParam("page","0")
                        .queryParam("name","my_name").build();

    HttpEntity<String> requestEntity = new HttpEntity<>(null, getHeaders());

    ResponseEntity<String> strResponse = restTemplate.exchange(builder.toUriString(),HttpMethod.GET, requestEntity,
                        String.class,uriParam);

    //final URL: http://my-rest-url.org/rest/account/my_account?pageSize=2&page=0&name=my_name

RestTemplate:使用UriComponents (URI变量和请求参数)构建动态URI

至少从Spring 3开始，许多RestTemplate方法不是使用UriComponentsBuilder来构建URL(这有点啰嗦)，而是在参数路径中接受占位符(不仅仅是交换)。

从文档中可以看到:

Many of the RestTemplate methods accepts a URI template and URI template variables, either as a String vararg, or as Map<String,String>. For example with a String vararg: restTemplate.getForObject( "http://example.com/hotels/{hotel}/rooms/{room}", String.class, "42", "21"); Or with a Map<String, String>: Map<String, String> vars = new HashMap<>(); vars.put("hotel", "42"); vars.put("room", "21"); restTemplate.getForObject("http://example.com/hotels/{hotel}/rooms/{room}", String.class, vars);

参考:https://docs.spring.io/spring/docs/current/spring-framework-reference/integration.html # rest-resttemplate-uri

如果你查看JavaDoc for RestTemplate并搜索“URI Template”，你可以看到哪些方法可以使用占位符。