I have to make a REST
call that includes custom headers and query parameters. I set my HttpEntity
with just the headers (no body), and I use the RestTemplate.exchange()
method as follows:
HttpHeaders headers = new HttpHeaders();
headers.set("Accept", "application/json");
Map<String, String> params = new HashMap<String, String>();
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 entity = new HttpEntity(headers);
HttpEntity<String> response = restTemplate.exchange(url, HttpMethod.GET, entity, String.class, params);
This fails at the client end with the dispatcher servlet
being unable to resolve the request to a handler. Having debugged it, it looks like the request parameters are not being sent.
When I do a an exchange with a POST
using a request body and no query parameters it works just fine.
Does anyone have any ideas?
If your url is http://localhost:8080/context path?msisdn={msisdn}&email={email}
then
Map<String,Object> queryParams=new HashMap<>();
queryParams.put("msisdn",your value)
queryParams.put("email",your value)
works for resttemplate exchange method as described by you
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: Build dynamic URI using UriComponents (URI variable and Request parameters)
To easily manipulate URLs / path / params / etc., you can use Spring's UriComponentsBuilder class. It's cleaner than manually concatenating strings and it takes care of the URL encoding for you:
HttpHeaders headers = new HttpHeaders();
headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);
UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url)
.queryParam("msisdn", msisdn)
.queryParam("email", email)
.queryParam("clientVersion", clientVersion)
.queryParam("clientType", clientType)
.queryParam("issuerName", issuerName)
.queryParam("applicationName", applicationName);
HttpEntity<?> entity = new HttpEntity<>(headers);
HttpEntity<String> response = restTemplate.exchange(
builder.toUriString(),
HttpMethod.GET,
entity,
String.class);
public static void main(String[] args) {
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.set("Accept", MediaType.APPLICATION_JSON_VALUE);
final String url = "https://host:port/contract/{code}";
Map<String, String> params = new HashMap<String, String>();
params.put("code", "123456");
HttpEntity<?> httpEntity = new HttpEntity<>(httpHeaders);
RestTemplate restTemplate = new RestTemplate();
restTemplate.exchange(url, HttpMethod.GET, httpEntity,String.class, params);
}
Converting of a hash map to a string of query parameters:
Map<String, 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);
UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url);
for (Map.Entry<String, String> entry : params.entrySet()) {
builder.queryParam(entry.getKey(), entry.getValue());
}
HttpHeaders headers = new HttpHeaders();
headers.set("Accept", "application/json");
HttpEntity<String> response = restTemplate.exchange(builder.toUriString(), HttpMethod.GET, new HttpEntity(headers), String.class);
If you pass non-parametrized params for RestTemplate, you'll have one Metrics for everyone single different URL that you pass, considering the parameters. You would like to use parametrized urls:
http://my-url/action?param1={param1}¶m2={param2}
instead of
http://my-url/action?param1=XXXX¶m2=YYYY
The second case is what you get by using UriComponentsBuilder class.
One way to implement the first behavior is the following:
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);
I am providing a code snippet of RestTemplate GET method with path param example
public ResponseEntity<String> getName(int id) {
final String url = "http://localhost:8080/springrestexample/employee/name?id={id}";
Map<String, String> params = new HashMap<String, String>();
params.put("id", id);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity request = new HttpEntity(headers);
ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.GET, String.class, params);
return response;
}
In Spring Web 4.3.6 I also see
public <T> T getForObject(String url, Class<T> responseType, Object... uriVariables)
That means you don't have to create an ugly map
So if you have this url
http://my-url/action?param1={param1}¶m2={param2}
You can either do
restTemplate.getForObject(url, Response.class, param1, param2)
or
restTemplate.getForObject(url, Response.class, param [])
I take different approach, you may agree or not but I want to control from .properties file instead of compiled Java code
endpoint.url = https://yourHost/resource?requestParam1={0}&requestParam2={1}
Java code goes here, you can write if or switch condition to find out if endpoint URL in .properties file has @PathVariable (contains {}) or @RequestParam (yourURL?key=value) etc... then invoke method accordingly... that way its dynamic and not need to code change in future one stop shop...
I'm trying to give more of idea than actual code here ...try to write generic method each for @RequestParam, and @PathVariable etc... then call accordingly when needed
@Value("${endpoint.url}")
private String endpointURL;
// you can use variable args feature in Java
public String requestParamMethodNameHere(String value1, String value2) {
RestTemplate restTemplate = new RestTemplate();
restTemplate
.getMessageConverters()
.add(new MappingJackson2HttpMessageConverter());
HttpHeaders headers = new HttpHeaders();
headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);
HttpEntity<String> entity = new HttpEntity<>(headers);
try {
String formatted_URL = MessageFormat.format(endpointURL, value1, value2);
ResponseEntity<String> response = restTemplate.exchange(
formatted_URL ,
HttpMethod.GET,
entity,
String.class);
return response.getBody();
} catch (Exception e) { e.printStackTrace(); }
I was attempting something similar, and the RoboSpice example helped me work it out:
HttpHeaders headers = new HttpHeaders();
headers.set("Accept", "application/json");
HttpEntity<String> request = new HttpEntity<>(input, createHeader());
String url = "http://awesomesite.org";
Uri.Builder uriBuilder = Uri.parse(url).buildUpon();
uriBuilder.appendQueryParameter(key, value);
uriBuilder.appendQueryParameter(key, value);
...
String url = uriBuilder.build().toString();
HttpEntity<String> response = restTemplate.exchange(url, HttpMethod.GET, request , String.class);
The uriVariables are also expanded in the query string. For example, the following call will expand values for both, account and name:
restTemplate.exchange("http://my-rest-url.org/rest/account/{account}?name={name}",
HttpMethod.GET,
httpEntity,
clazz,
"my-account",
"my-name"
);
so the actual request url will be
http://my-rest-url.org/rest/account/my-account?name=my-name
Look at HierarchicalUriComponents.expandInternal(UriTemplateVariables) for more details. Version of Spring is 3.1.3.
Since at least Spring 3, instead of using UriComponentsBuilder
to build the URL (which is a bit verbose), many of the RestTemplate
methods accept placeholders in the path for parameters (not just exchange
).
From the documentation:
Many of the
RestTemplate
methods accepts a URI template and URI template variables, either as aString
vararg, or asMap<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);
If you look at the JavaDoc for RestTemplate
and search for "URI Template", you can see which methods you can use placeholders with.
Source: Stackoverflow.com