How do you create a REST client for Java

Question

With JSR 311 and its implementations we have a powerful standard for exposing Java objects via REST  However on the client side there seems to be something missing that is comparable to Apache Axis for SOAP - something that hides the web service and marshals the data transparently back to Java objects   How do you create Java RESTful clients  Using HTTPConnection and manual parsing of the result  Or specialized clients for e g  Jersey or Apache CXR

User · Answer

I ve recently tried Retrofit Library from square  Its great and you can call your rest API very easily   Annotation based configuration allows us to get rid of lot of boiler plate coding

User · Answer

This is an old question  2008  so there are many more options now than there were then    Apache CXF has three different REST Client options Jersey  mentioned above   Spring RestTemplate superceded by Spring WebClient Commons HTTP Client build your own for older Java projects    UPDATES  projects still active in 2020     Apache HTTP Components  4 2  Fluent adapter - Basic replacement for JDK  used by several other candidates in this list  Better than old Commons HTTP Client 3 and easier to use for building your own REST client  You ll have to use something like Jackson for JSON parsing support and you can use HTTP components URIBuilder to construct resource URIs similar to Jersey JAX-RS Rest client  HTTP components also supports NIO but I doubt you will get better performance than BIO given the short requestnature of REST  Apache HttpComponents 5 has HTTP 2 support  OkHttp - Basic replacement for JDK  similar to http components  used by several other candidates in this list  Supports newer HTTP protocols  SPDY and HTTP2   Works on Android  Unfortunately it does not offer a true reactor-loop based async option  see Ning and HTTP components above   However if you use the newer HTTP2 protocol this is less of a problem  assuming connection count is  problem   Ning Async-http-client - provides NIO support  Previously known as Async-http-client by Sonatype  Feign   wrapper for lower level http clients  okhttp  apache httpcomponents   Auto-creates clients based on interface stubs similar to some Jersey and CXF extensions  Strong spring integration  Retrofit - wrapper for lower level http clients  okhttp   Auto-creates clients based on interface stubs similar to some Jersey and CXF extensions  Volley     wrapper for jdk http client  by google google-http wrapper for jdk http client  or apache httpcomponents  by google Unirest    wrapper for jdk http client  by kong Resteasy   JakartaEE wrapper for jdk http client  by jboss  part of jboss framework jcabi-http wrapper for apache httpcomponents  part of jcabi collection restlet wrapper for apache httpcomponents  part of restlet framework rest-assured wrapper with asserts for easy testing   A caveat on picking HTTP REST clients  Make sure to check what your framework stack is using for an HTTP client  how it does threading  and ideally use the same client if it offers one  That is if your using something like Vert x or Play you may want to try to use its backing client to participate in whatever bus or reactor loop the framework provides    otherwise be prepared for possibly interesting threading issues

User · Answer

I use Apache HTTPClient to handle all the HTTP side of things   I write XML SAX parsers for the XML content that parses the XML into your object model  I believe that Axis2 also exposes XML -  Model methods  Axis 1 hid this part  annoyingly   XML generators are trivially simple   It doesn t take long to code  and is quite efficient  in my opinion

User · Answer

You could try Rapa  Let us know your feedback about the same  And feel free to log issues or expected features

User · Answer

I used RestAssured most of the time to parse rest service response and test the services  Apart from Rest Assured  I used below libraries too to communicate with Resful services   a  Jersey Rest Client  b  Spring RestTemplate  c  Apache HTTP Client

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You can also check Restlet which has full client-side capabilities  more REST oriented that lower-level libraries such as HttpURLConnection or Apache HTTP Client  which we can leverage as connectors    Best regards  Jerome Louvel

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OkHttp is lightweight and powerful when combined with Retrofit as well   This works well for general Java use as well as on Android   OkHttp  http   square github io okhttp   public static final MediaType JSON       MediaType parse  application json  charset utf-8     OkHttpClient client   new OkHttpClient     String post String url  String json  throws IOException     RequestBody body   RequestBody create JSON  json     Request request   new Request Builder          url url         post body         build      Response response   client newCall request  execute      return response body   string        Retrofit  http   square github io retrofit   public interface GitHubService      GET   users  user  repos     Call lt List lt Repo gt  gt  listRepos  Path  user   String user

User · Answer

I d like to point out 2 more options    Restfulie  based on the VRaptor web framework  has both server and client side implementations with very good Hypermedia support  RESTEasy has a JAX-RS proxy based client implementation

User · Answer

You can also check Restlet which has full client-side capabilities  more REST oriented that lower-level libraries such as HttpURLConnection or Apache HTTP Client  which we can leverage as connectors    Best regards  Jerome Louvel

User · Answer

I used RestAssured most of the time to parse rest service response and test the services  Apart from Rest Assured  I used below libraries too to communicate with Resful services   a  Jersey Rest Client  b  Spring RestTemplate  c  Apache HTTP Client

User · Answer

Try JdkRequest from jcabi-http  I m a developer   This is how it works   String body   new JdkRequest  http   www google com      header  User-Agent    it s me      fetch      body     Check this blog post for more details  http   www yegor256 com 2014 04 11 jcabi-http-intro html

User · Answer

Since no one mentioned  here is another one  Feign  which is used by Spring Cloud

User · Answer

I ve recently tried Retrofit Library from square  Its great and you can call your rest API very easily   Annotation based configuration allows us to get rid of lot of boiler plate coding

User · Answer

As I mentioned in this thread I tend to use Jersey which implements JAX-RS and comes with a nice REST client  The nice thing is if you implement your RESTful resources using JAX-RS then the Jersey client can reuse the entity providers such as for JAXB XML JSON Atom and so forth - so you can reuse the same objects on the server side as you use on the client side unit test   For example here is a unit test case from the Apache Camel project which looks up XML payloads from a RESTful resource  using the JAXB object Endpoints   The resource uri  method is defined in this base class which just uses the Jersey client API   e g        clientConfig   new DefaultClientConfig        client   Client create clientConfig        resource   client resource  http   localhost 8080           lets get the XML as a String     String text   resource  foo   accept  application xml   get String class             BTW I hope that future version of JAX-RS add a nice client side API along the lines of the one in Jersey

User · Answer

Try JdkRequest from jcabi-http  I m a developer   This is how it works   String body   new JdkRequest  http   www google com      header  User-Agent    it s me      fetch      body     Check this blog post for more details  http   www yegor256 com 2014 04 11 jcabi-http-intro html

User · Answer

I use Apache HTTPClient to handle all the HTTP side of things   I write XML SAX parsers for the XML content that parses the XML into your object model  I believe that Axis2 also exposes XML -  Model methods  Axis 1 hid this part  annoyingly   XML generators are trivially simple   It doesn t take long to code  and is quite efficient  in my opinion

User · Answer

This is an old question  2008  so there are many more options now than there were then    Apache CXF has three different REST Client options Jersey  mentioned above   Spring RestTemplate superceded by Spring WebClient Commons HTTP Client build your own for older Java projects    UPDATES  projects still active in 2020     Apache HTTP Components  4 2  Fluent adapter - Basic replacement for JDK  used by several other candidates in this list  Better than old Commons HTTP Client 3 and easier to use for building your own REST client  You ll have to use something like Jackson for JSON parsing support and you can use HTTP components URIBuilder to construct resource URIs similar to Jersey JAX-RS Rest client  HTTP components also supports NIO but I doubt you will get better performance than BIO given the short requestnature of REST  Apache HttpComponents 5 has HTTP 2 support  OkHttp - Basic replacement for JDK  similar to http components  used by several other candidates in this list  Supports newer HTTP protocols  SPDY and HTTP2   Works on Android  Unfortunately it does not offer a true reactor-loop based async option  see Ning and HTTP components above   However if you use the newer HTTP2 protocol this is less of a problem  assuming connection count is  problem   Ning Async-http-client - provides NIO support  Previously known as Async-http-client by Sonatype  Feign   wrapper for lower level http clients  okhttp  apache httpcomponents   Auto-creates clients based on interface stubs similar to some Jersey and CXF extensions  Strong spring integration  Retrofit - wrapper for lower level http clients  okhttp   Auto-creates clients based on interface stubs similar to some Jersey and CXF extensions  Volley     wrapper for jdk http client  by google google-http wrapper for jdk http client  or apache httpcomponents  by google Unirest    wrapper for jdk http client  by kong Resteasy   JakartaEE wrapper for jdk http client  by jboss  part of jboss framework jcabi-http wrapper for apache httpcomponents  part of jcabi collection restlet wrapper for apache httpcomponents  part of restlet framework rest-assured wrapper with asserts for easy testing   A caveat on picking HTTP REST clients  Make sure to check what your framework stack is using for an HTTP client  how it does threading  and ideally use the same client if it offers one  That is if your using something like Vert x or Play you may want to try to use its backing client to participate in whatever bus or reactor loop the framework provides    otherwise be prepared for possibly interesting threading issues

User · Answer

If you only wish to invoke a REST service and parse the response you can try out Rest Assured     Make a GET request to   lotto  String json   get   lotto   asString      Parse the JSON response List lt String gt  winnderIds   with json  get  lotto winners winnerId        Make a POST request to   shopping  String xml   post   shopping   andReturn   body   asString      Parse the XML Node category   with xml  get  shopping category 0

User · Answer

I use Apache HTTPClient to handle all the HTTP side of things   I write XML SAX parsers for the XML content that parses the XML into your object model  I believe that Axis2 also exposes XML -  Model methods  Axis 1 hid this part  annoyingly   XML generators are trivially simple   It doesn t take long to code  and is quite efficient  in my opinion

User · Answer

You can also check Restlet which has full client-side capabilities  more REST oriented that lower-level libraries such as HttpURLConnection or Apache HTTP Client  which we can leverage as connectors    Best regards  Jerome Louvel

User · Answer

Examples of jersey Rest client   Adding dependency               lt  -- jersey -- gt       lt dependency gt           lt groupId gt com sun jersey lt  groupId gt           lt artifactId gt jersey-json lt  artifactId gt           lt version gt 1 8 lt  version gt       lt  dependency gt      lt dependency gt           lt groupId gt com sun jersey lt  groupId gt           lt artifactId gt jersey-server lt  artifactId gt           lt version gt 1 8 lt  version gt       lt  dependency gt    lt dependency gt       lt groupId gt com sun jersey lt  groupId gt       lt artifactId gt jersey-client lt  artifactId gt       lt version gt 1 8 lt  version gt   lt  dependency gt        lt dependency gt       lt groupId gt org json lt  groupId gt       lt artifactId gt json lt  artifactId gt       lt version gt 20090211 lt  version gt   lt  dependency gt    ForGetMethod and passing two parameter               Client client   Client create               WebResource webResource1   client                          resource  http   localhost 10102 NewsTickerServices AddGroup                                     userN         groupName                    ClientResponse response1   webResource1 get ClientResponse class                   System out println  responser is    response1     GetMethod  passing one parameter and Getting a Respone of List                Client client   Client create             WebResource webResource1   client                      resource  http   localhost 10102 NewsTickerServices GetAssignedUser   grpName             value changed     String response1   webResource1 type MediaType APPLICATION JSON  get String class        List  lt String  gt  Assignedlist  new ArrayList lt String gt          JSONArray jsonArr2  new JSONArray response1       for  int i  0 i lt jsonArr2 length   i              Assignedlist add jsonArr2 getString i                In Above It Returns a List which we are accepting as a List and then converting it to Json Array and then Json Array to List     If  Post Request passing Json Object as Parameter        Client client   Client create        WebResource webResource   client              resource  http   localhost 10102 NewsTickerServices CreateJUser           value added      ClientResponse response   webResource type MediaType APPLICATION JSON  post ClientResponse class mapper writeValueAsString user         if  response getStatus      500             context addMessage null  new FacesMessage  User already exist

User · Answer

You can also check Restlet which has full client-side capabilities  more REST oriented that lower-level libraries such as HttpURLConnection or Apache HTTP Client  which we can leverage as connectors    Best regards  Jerome Louvel

User · Answer

OkHttp is lightweight and powerful when combined with Retrofit as well   This works well for general Java use as well as on Android   OkHttp  http   square github io okhttp   public static final MediaType JSON       MediaType parse  application json  charset utf-8     OkHttpClient client   new OkHttpClient     String post String url  String json  throws IOException     RequestBody body   RequestBody create JSON  json     Request request   new Request Builder          url url         post body         build      Response response   client newCall request  execute      return response body   string        Retrofit  http   square github io retrofit   public interface GitHubService      GET   users  user  repos     Call lt List lt Repo gt  gt  listRepos  Path  user   String user

User · Answer

I d like to point out 2 more options    Restfulie  based on the VRaptor web framework  has both server and client side implementations with very good Hypermedia support  RESTEasy has a JAX-RS proxy based client implementation

User · Answer

I am currently using https   github com kevinsawicki http-request I like their simplicity and the way examples are shown  but mostly I was sold when I read   What are the dependencies  None  The goal of this library is to be a single class class with some inner static classes  The test project does require Jetty in order to test requests against an actual HTTP server implementation   which sorted out some problems on a java 1 6 project  As for decoding json into objects gson is just invincible

User · Answer

You can use the standard Java SE APIs   private void updateCustomer Customer customer         try            URL url   new URL  http   www example com customers             HttpURLConnection connection    HttpURLConnection  url openConnection             connection setDoOutput true            connection setInstanceFollowRedirects false            connection setRequestMethod  PUT             connection setRequestProperty  Content-Type    application xml              OutputStream os   connection getOutputStream             jaxbContext createMarshaller   marshal customer  os            os flush              connection getResponseCode             connection disconnect           catch Exception e             throw new RuntimeException e                Or you can use the REST client APIs provided by JAX-RS implementations such as Jersey  These APIs are easier to use  but require additional jars on your class path   WebResource resource   client resource  http   www example com customers     ClientResponse response   resource type  application xml     put ClientResponse class    lt customer gt     lt  customer      System out println response      For more information see    http   bdoughan blogspot com 2010 08 creating-restful-web-service-part-55 html

User · Answer

I am currently using https   github com kevinsawicki http-request I like their simplicity and the way examples are shown  but mostly I was sold when I read   What are the dependencies  None  The goal of this library is to be a single class class with some inner static classes  The test project does require Jetty in order to test requests against an actual HTTP server implementation   which sorted out some problems on a java 1 6 project  As for decoding json into objects gson is just invincible

User · Answer

Examples of jersey Rest client   Adding dependency               lt  -- jersey -- gt       lt dependency gt           lt groupId gt com sun jersey lt  groupId gt           lt artifactId gt jersey-json lt  artifactId gt           lt version gt 1 8 lt  version gt       lt  dependency gt      lt dependency gt           lt groupId gt com sun jersey lt  groupId gt           lt artifactId gt jersey-server lt  artifactId gt           lt version gt 1 8 lt  version gt       lt  dependency gt    lt dependency gt       lt groupId gt com sun jersey lt  groupId gt       lt artifactId gt jersey-client lt  artifactId gt       lt version gt 1 8 lt  version gt   lt  dependency gt        lt dependency gt       lt groupId gt org json lt  groupId gt       lt artifactId gt json lt  artifactId gt       lt version gt 20090211 lt  version gt   lt  dependency gt    ForGetMethod and passing two parameter               Client client   Client create               WebResource webResource1   client                          resource  http   localhost 10102 NewsTickerServices AddGroup                                     userN         groupName                    ClientResponse response1   webResource1 get ClientResponse class                   System out println  responser is    response1     GetMethod  passing one parameter and Getting a Respone of List                Client client   Client create             WebResource webResource1   client                      resource  http   localhost 10102 NewsTickerServices GetAssignedUser   grpName             value changed     String response1   webResource1 type MediaType APPLICATION JSON  get String class        List  lt String  gt  Assignedlist  new ArrayList lt String gt          JSONArray jsonArr2  new JSONArray response1       for  int i  0 i lt jsonArr2 length   i              Assignedlist add jsonArr2 getString i                In Above It Returns a List which we are accepting as a List and then converting it to Json Array and then Json Array to List     If  Post Request passing Json Object as Parameter        Client client   Client create        WebResource webResource   client              resource  http   localhost 10102 NewsTickerServices CreateJUser           value added      ClientResponse response   webResource type MediaType APPLICATION JSON  post ClientResponse class mapper writeValueAsString user         if  response getStatus      500             context addMessage null  new FacesMessage  User already exist

User · Answer

I wrote a library that maps a java interface to a remote JSON REST service   https   github com ggeorgovassilis spring-rest-invoker  public interface BookService       RequestMapping   volumes      QueryResult findBooksByTitle  RequestParam  q   String q        RequestMapping   volumes  id       Item findBookById  PathVariable  id   String id

User · Answer

Though its simple to create a HTTP client and make a reuest  But if you want to make use of some auto generated clients   You can make use of WADL to describe and generate code    You can use RestDescribe to generate and compile WSDL  you can generate clients in php  ruby  python  java and C  using this  It generates clean code and there is a good change that you have to tweak it a bit after code generation  you can find good documentation and underlying thoughts behind the tool here   There are few interesting and useful WADL tools mentioned on wintermute

User · Answer

Try looking at http-rest-client  https   github com g00dnatur3 http-rest-client  Here is a simple example   RestClient client   RestClient builder   build    String geocoderUrl    http   maps googleapis com maps api geocode json  Map lt String  String gt  params   Maps newHashMap    params put  address    beverly hills 90210    params put  sensor    false    JsonNode node   client get geocoderUrl  params  JsonNode class     The library takes care of json serialization and binding for you   Here is another example    RestClient client   RestClient builder   build    String url       Person person       Header header   client create url  person   if  header    null  System out println  Location header is     header value       And one last example   RestClient client   RestClient builder   build    String url       Person person   client get url  null  Person class     no queryParams   Cheers

User · Answer

Try looking at http-rest-client  https   github com g00dnatur3 http-rest-client  Here is a simple example   RestClient client   RestClient builder   build    String geocoderUrl    http   maps googleapis com maps api geocode json  Map lt String  String gt  params   Maps newHashMap    params put  address    beverly hills 90210    params put  sensor    false    JsonNode node   client get geocoderUrl  params  JsonNode class     The library takes care of json serialization and binding for you   Here is another example    RestClient client   RestClient builder   build    String url       Person person       Header header   client create url  person   if  header    null  System out println  Location header is     header value       And one last example   RestClient client   RestClient builder   build    String url       Person person   client get url  null  Person class     no queryParams   Cheers

User · Answer

As I mentioned in this thread I tend to use Jersey which implements JAX-RS and comes with a nice REST client  The nice thing is if you implement your RESTful resources using JAX-RS then the Jersey client can reuse the entity providers such as for JAXB XML JSON Atom and so forth - so you can reuse the same objects on the server side as you use on the client side unit test   For example here is a unit test case from the Apache Camel project which looks up XML payloads from a RESTful resource  using the JAXB object Endpoints   The resource uri  method is defined in this base class which just uses the Jersey client API   e g        clientConfig   new DefaultClientConfig        client   Client create clientConfig        resource   client resource  http   localhost 8080           lets get the XML as a String     String text   resource  foo   accept  application xml   get String class             BTW I hope that future version of JAX-RS add a nice client side API along the lines of the one in Jersey

User · Answer

I use Apache HTTPClient to handle all the HTTP side of things   I write XML SAX parsers for the XML content that parses the XML into your object model  I believe that Axis2 also exposes XML -  Model methods  Axis 1 hid this part  annoyingly   XML generators are trivially simple   It doesn t take long to code  and is quite efficient  in my opinion

User · Answer

You could try Rapa  Let us know your feedback about the same  And feel free to log issues or expected features

User · Answer

Though its simple to create a HTTP client and make a reuest  But if you want to make use of some auto generated clients   You can make use of WADL to describe and generate code    You can use RestDescribe to generate and compile WSDL  you can generate clients in php  ruby  python  java and C  using this  It generates clean code and there is a good change that you have to tweak it a bit after code generation  you can find good documentation and underlying thoughts behind the tool here   There are few interesting and useful WADL tools mentioned on wintermute

User · Answer

I wrote a library that maps a java interface to a remote JSON REST service   https   github com ggeorgovassilis spring-rest-invoker  public interface BookService       RequestMapping   volumes      QueryResult findBooksByTitle  RequestParam  q   String q        RequestMapping   volumes  id       Item findBookById  PathVariable  id   String id

User · Answer

As I mentioned in this thread I tend to use Jersey which implements JAX-RS and comes with a nice REST client  The nice thing is if you implement your RESTful resources using JAX-RS then the Jersey client can reuse the entity providers such as for JAXB XML JSON Atom and so forth - so you can reuse the same objects on the server side as you use on the client side unit test   For example here is a unit test case from the Apache Camel project which looks up XML payloads from a RESTful resource  using the JAXB object Endpoints   The resource uri  method is defined in this base class which just uses the Jersey client API   e g        clientConfig   new DefaultClientConfig        client   Client create clientConfig        resource   client resource  http   localhost 8080           lets get the XML as a String     String text   resource  foo   accept  application xml   get String class             BTW I hope that future version of JAX-RS add a nice client side API along the lines of the one in Jersey

User · Answer

Since no one mentioned  here is another one  Feign  which is used by Spring Cloud

User · Answer

If you only wish to invoke a REST service and parse the response you can try out Rest Assured     Make a GET request to   lotto  String json   get   lotto   asString      Parse the JSON response List lt String gt  winnderIds   with json  get  lotto winners winnerId        Make a POST request to   shopping  String xml   post   shopping   andReturn   body   asString      Parse the XML Node category   with xml  get  shopping category 0

User · Answer

As I mentioned in this thread I tend to use Jersey which implements JAX-RS and comes with a nice REST client  The nice thing is if you implement your RESTful resources using JAX-RS then the Jersey client can reuse the entity providers such as for JAXB XML JSON Atom and so forth - so you can reuse the same objects on the server side as you use on the client side unit test   For example here is a unit test case from the Apache Camel project which looks up XML payloads from a RESTful resource  using the JAXB object Endpoints   The resource uri  method is defined in this base class which just uses the Jersey client API   e g        clientConfig   new DefaultClientConfig        client   Client create clientConfig        resource   client resource  http   localhost 8080           lets get the XML as a String     String text   resource  foo   accept  application xml   get String class             BTW I hope that future version of JAX-RS add a nice client side API along the lines of the one in Jersey

User · Answer

You can use the standard Java SE APIs   private void updateCustomer Customer customer         try            URL url   new URL  http   www example com customers             HttpURLConnection connection    HttpURLConnection  url openConnection             connection setDoOutput true            connection setInstanceFollowRedirects false            connection setRequestMethod  PUT             connection setRequestProperty  Content-Type    application xml              OutputStream os   connection getOutputStream             jaxbContext createMarshaller   marshal customer  os            os flush              connection getResponseCode             connection disconnect           catch Exception e             throw new RuntimeException e                Or you can use the REST client APIs provided by JAX-RS implementations such as Jersey  These APIs are easier to use  but require additional jars on your class path   WebResource resource   client resource  http   www example com customers     ClientResponse response   resource type  application xml     put ClientResponse class    lt customer gt     lt  customer      System out println response      For more information see    http   bdoughan blogspot com 2010 08 creating-restful-web-service-part-55 html

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