Spring RestTemplate GET with parameters

Question

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 lt String  String gt  params   new HashMap lt String  String gt     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 lt String gt  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

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I was attempting something similar  and the RoboSpice example helped me work it out   HttpHeaders headers   new HttpHeaders    headers set  Accept    application json     HttpEntity lt String gt  request   new HttpEntity lt  gt  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 lt String gt  response   restTemplate exchange url  HttpMethod GET  request   String class

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I take different approach  you may agree or not but I want to control from  properties file instead of compiled Java code  Inside application properties file  endpoint url   https   yourHost resource requestParam1  0  amp 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 lt String gt  entity   new HttpEntity lt  gt  headers        try         String formatted URL   MessageFormat format endpointURL  value1  value2         ResponseEntity lt String gt  response   restTemplate exchange                      formatted URL                       HttpMethod GET                      entity                      String class        return response getBody          catch  Exception e    e printStackTrace

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Converting of a hash map to a string of query parameters   Map lt String  String gt  params   new HashMap lt  gt     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 lt String  String gt  entry   params entrySet          builder queryParam entry getKey    entry getValue        HttpHeaders headers   new HttpHeaders    headers set  Accept    application json     HttpEntity lt String gt  response   restTemplate exchange builder toUriString    HttpMethod GET  new HttpEntity headers   String class

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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

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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  amp param2  param2    instead of  http   my-url action param1 XXXX amp param2 YYYY   The second case is what you get by using UriComponentsBuilder class   One way to implement the first behavior is the following   Map lt String  Object gt  params   new HashMap lt  gt     params put  param1    XXXX    params put  param2    YYYY     String url    http   my-url action  s    String parametrizedArgs   params keySet   stream   map k - gt      String format   s   s    k  k    collect Collectors joining   amp       HttpHeaders headers   new HttpHeaders    headers set  Accept   MediaType APPLICATION JSON VALUE   HttpEntity lt String gt  entity   new HttpEntity lt  gt  headers    restTemplate exchange String format url  parametrizedArgs   HttpMethod GET  entity  String class  params

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String uri   http   my-rest-url org rest account  account        Map lt String  String gt  uriParam   new HashMap lt  gt         uriParam put  account    my account         UriComponents builder   UriComponentsBuilder fromHttpUrl uri                   queryParam  pageSize   2                            queryParam  page   0                            queryParam  name   my name   build         HttpEntity lt String gt  requestEntity   new HttpEntity lt  gt  null  getHeaders          ResponseEntity lt String gt  strResponse   restTemplate exchange builder toUriString   HttpMethod GET  requestEntity                          String class uriParam          final URL  http   my-rest-url org rest account my account pageSize 2 amp page 0 amp name my name   RestTemplate  Build dynamic URI using UriComponents  URI variable and Request parameters

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OK  so I m being an idiot and I m confusing query parameters with url parameters  I was kinda hoping there would be a nicer way to populate my query parameters rather than an ugly concatenated String but there we are  It s simply a case of build the URL with the correct parameters  If you pass it as a String Spring will also take care of the encoding for you

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In Spring Web 4 3 6 I also see  public  lt T gt  T getForObject String url  Class lt T gt  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  amp param2  param2    You can either do  restTemplate getForObject url  Response class  param1  param2    or  restTemplate getForObject url  Response class  param

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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  quot Accept quot   MediaType APPLICATION JSON VALUE    UriComponentsBuilder builder   UriComponentsBuilder fromHttpUrl url           queryParam  quot msisdn quot   msisdn           queryParam  quot email quot   email           queryParam  quot clientVersion quot   clientVersion           queryParam  quot clientType quot   clientType           queryParam  quot issuerName quot   issuerName           queryParam  quot applicationName quot   applicationName    HttpEntity lt   gt  entity   new HttpEntity lt  gt  headers    HttpEntity lt String gt  response   restTemplate exchange          builder toUriString             HttpMethod GET           entity           String class

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If your url is http   localhost 8080 context path msisdn  msisdn  amp email  email   then   Map lt String Object gt  queryParams new HashMap lt  gt     queryParams put  msisdn  your value  queryParams put  email  your value    works for resttemplate exchange method as described by you

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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 lt String  String gt  params   new HashMap lt String  String gt              params put  code    123456             HttpEntity lt   gt  httpEntity    new HttpEntity lt  gt  httpHeaders             RestTemplate restTemplate    new RestTemplate             restTemplate exchange url  HttpMethod GET  httpEntity String class  params

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I am providing a code snippet of RestTemplate GET method with path param example public ResponseEntity lt String gt  getName int id        final String url    quot http   localhost 8080 springrestexample employee name id  id  quot       Map lt String  String gt  params   new HashMap lt String  String gt         params put  quot id quot   id       HttpHeaders headers   new HttpHeaders        headers setContentType MediaType APPLICATION JSON       HttpEntity request   new HttpEntity headers       ResponseEntity lt String gt  response   restTemplate exchange url  HttpMethod GET  String class  params       return response

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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 a String vararg  or as   Map lt String String gt        For example with a String vararg   restTemplate getForObject      http   example com hotels  hotel  rooms  room    String class   42    21          Or with a Map lt String  String gt    Map lt String  String gt  vars   new HashMap lt  gt     vars put  hotel    42    vars put  room    21     restTemplate getForObject  http   example com hotels  hotel  rooms  room         String class  vars      Reference  https   docs spring io spring docs current spring-framework-reference integration html rest-resttemplate-uri  If you look at the JavaDoc for RestTemplate and search for  URI Template   you can see which methods you can use placeholders with

[java] Spring RestTemplate GET with parameters

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