add oauth support to feign client

modules/swagger-codegen/src/main/resources/Java/libraries/feign/ApiClient.mustache

@@ -3,6 +3,9 @@ package {{invokerPackage}};
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.AuthenticationRequestBuilder;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.TokenRequestBuilder;
+
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
@@ -13,6 +16,7 @@ import feign.jackson.JacksonDecoder;
 import feign.jackson.JacksonEncoder;
 import feign.slf4j.Slf4jLogger;
 import {{invokerPackage}}.auth.*;
+import {{invokerPackage}}.auth.OAuth.AccessTokenListener;
 
 {{>generatedAnnotation}}
 public class ApiClient {
@@ -77,10 +81,32 @@ public class ApiClient {
     this.setCredentials(username,  password);
   }
 
+  /**
+   * Helper constructor for single password oauth2
+   * @param authName
+   * @param clientId
+   * @param secret
+   * @param username
+   * @param password
+   */
+   public ApiClient(String authName, String clientId, String secret, String username, String password) {
+     this(authName);
+     this.getTokenEndPoint()
+            .setClientId(clientId)
+            .setClientSecret(secret)
+            .setUsername(username)
+            .setPassword(password);
+   }
+
   public String getBasePath() {
     return basePath;
   }
 
+  public ApiClient setBasePath(String basePath) {
+    this.basePath = basePath;
+    return this;
+  }
+
   public Map<String, RequestInterceptor> getApiAuthorizations() {
     return apiAuthorizations;
   }
@@ -89,11 +115,6 @@ public class ApiClient {
     this.apiAuthorizations = apiAuthorizations;
   }
 
-  public ApiClient setBasePath(String basePath) {
-    this.basePath = basePath;
-    return this;
-  }
-
   public Feign.Builder getFeignBuilder() {
     return feignBuilder;
   }
@@ -180,8 +201,92 @@ public class ApiClient {
         basicAuth.setCredentials(username, password);
         return;
       }
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.getTokenRequestBuilder().setUsername(username).setPassword(password);
+        return;
+      }
+    }
+    throw new RuntimeException("No Basic authentication or OAuth configured!");
+  }
+
+  /**
+   * Helper method to configure the token endpoint of the first oauth found in the apiAuthorizations (there should be only one)
+   * @return
+   */
+  public TokenRequestBuilder getTokenEndPoint() {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        return oauth.getTokenRequestBuilder();
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Helper method to configure authorization endpoint of the first oauth found in the apiAuthorizations (there should be only one)
+   * @return
+   */
+  public AuthenticationRequestBuilder getAuthorizationEndPoint() {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        return oauth.getAuthenticationRequestBuilder();
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Helper method to pre-set the oauth access token of the first oauth found in the apiAuthorizations (there should be only one)
+   * @param accessToken
+   * @param expiresIn : validity period in seconds
+   */
+  public void setAccessToken(String accessToken, Long expiresIn) {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.setAccessToken(accessToken, expiresIn);
+        return;
+      }
+    }
+  }
+
+  /**
+   * Helper method to configure the oauth accessCode/implicit flow parameters
+   * @param clientId
+   * @param clientSecret
+   * @param redirectURI
+   */
+  public void configureAuthorizationFlow(String clientId, String clientSecret, String redirectURI) {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.getTokenRequestBuilder()
+                .setClientId(clientId)
+                .setClientSecret(clientSecret)
+                .setRedirectURI(redirectURI);
+        oauth.getAuthenticationRequestBuilder()
+                .setClientId(clientId)
+                .setRedirectURI(redirectURI);
+        return;
+      }
+    }
+  }
+
+  /**
+   * Configures a listener which is notified when a new access token is received.
+   * @param accessTokenListener
+   */
+  public void registerAccessTokenListener(AccessTokenListener accessTokenListener) {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.registerAccessTokenListener(accessTokenListener);
+        return;
+      }
     }
-    throw new RuntimeException("No Basic authentication configured!");
   }
 
   public RequestInterceptor getAuthorization(String authName) {

modules/swagger-codegen/src/main/resources/Java/libraries/feign/auth/OAuth.mustache

@@ -1,17 +1,203 @@
 package {{invokerPackage}}.auth;
 
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.oltu.oauth2.client.HttpClient;
+import org.apache.oltu.oauth2.client.OAuthClient;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.AuthenticationRequestBuilder;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.TokenRequestBuilder;
+import org.apache.oltu.oauth2.client.response.OAuthClientResponse;
+import org.apache.oltu.oauth2.client.response.OAuthClientResponseFactory;
+import org.apache.oltu.oauth2.client.response.OAuthJSONAccessTokenResponse;
+import org.apache.oltu.oauth2.common.exception.OAuthProblemException;
+import org.apache.oltu.oauth2.common.exception.OAuthSystemException;
+import org.apache.oltu.oauth2.common.message.types.GrantType;
+import org.apache.oltu.oauth2.common.token.BasicOAuthToken;
+
+import feign.Client;
+import feign.Request.Options;
 import feign.RequestInterceptor;
 import feign.RequestTemplate;
+import feign.Response;
+import feign.Util;
+import {{invokerPackage}}.StringUtil;
+
 
 public class OAuth implements RequestInterceptor {
 
+    public interface AccessTokenListener {
+        public void notify(BasicOAuthToken token);
+    }
+
+    private volatile String accessToken;
+    private Long expirationTimeMillis;
+    private OAuthClient oauthClient;
+    private TokenRequestBuilder tokenRequestBuilder;
+    private AuthenticationRequestBuilder authenticationRequestBuilder;
+    private AccessTokenListener accessTokenListener;
+
+    public OAuth(Client client, TokenRequestBuilder requestBuilder) {
+        setOauthClient(client);
+        this.tokenRequestBuilder = requestBuilder;
+    }
+
+    public OAuth(Client client, OAuthFlow flow, String authorizationUrl, String tokenUrl, String scopes) {
+        this(client, OAuthClientRequest.tokenLocation(tokenUrl).setScope(scopes));
+        setFlow(flow);
+        authenticationRequestBuilder = OAuthClientRequest.authorizationLocation(authorizationUrl);
+    }
+
     public OAuth(OAuthFlow flow, String authorizationUrl, String tokenUrl, String scopes) {
-        // TODO Not implemented yet
+        this(new Client.Default(null, null), flow, authorizationUrl, tokenUrl, scopes);
+    }
+
+    public void setFlow(OAuthFlow flow) {
+        switch(flow) {
+        case accessCode:
+        case implicit:
+            tokenRequestBuilder.setGrantType(GrantType.AUTHORIZATION_CODE);
+            break;
+        case password:
+            tokenRequestBuilder.setGrantType(GrantType.PASSWORD);
+            break;
+        case application:
+            tokenRequestBuilder.setGrantType(GrantType.CLIENT_CREDENTIALS);
+            break;
+        default:
+            break;
+        }
     }
 
     @Override
     public void apply(RequestTemplate template) {
-        // TODO Not implemented yet
+        // If the request already have an authorization (eg. Basic auth), do nothing
+        if (template.headers().containsKey("Authorization")) {
+            return;
+        }
+        // If first time, get the token
+        if (expirationTimeMillis == null || System.currentTimeMillis() >= expirationTimeMillis) {
+            try {
+                updateAccessToken();
+            } catch (OAuthSystemException e) {
+                e.printStackTrace();
+                return;
+            } catch (OAuthProblemException e) {
+                e.printStackTrace();
+                return;
+            }
+        }
+        if (getAccessToken() != null) {
+            template.header("Authorization", "Bearer " + getAccessToken());
+        }
     }
 
+    public synchronized void updateAccessToken() throws OAuthSystemException, OAuthProblemException {
+        if (getAccessToken() == null) {
+            OAuthJSONAccessTokenResponse accessTokenResponse = oauthClient.accessToken(tokenRequestBuilder.buildBodyMessage());
+            if (accessTokenResponse != null && accessTokenResponse.getAccessToken() != null) {
+                setAccessToken(accessTokenResponse.getAccessToken(), accessTokenResponse.getExpiresIn());
+                if (accessTokenListener != null) {
+                    accessTokenListener.notify((BasicOAuthToken) accessTokenResponse.getOAuthToken());
+                }
+            }
+        }
+    }
+
+    public void registerAccessTokenListener(AccessTokenListener accessTokenListener) {
+        this.accessTokenListener = accessTokenListener;
+    }
+
+    public synchronized String getAccessToken() {
+        return accessToken;
+    }
+
+    public synchronized void setAccessToken(String accessToken, Long expiresIn) {
+        this.accessToken = accessToken;
+        this.expirationTimeMillis = System.currentTimeMillis() + expiresIn * 1000;
+    }
+
+    public TokenRequestBuilder getTokenRequestBuilder() {
+        return tokenRequestBuilder;
+    }
+
+    public void setTokenRequestBuilder(TokenRequestBuilder tokenRequestBuilder) {
+        this.tokenRequestBuilder = tokenRequestBuilder;
+    }
+
+    public AuthenticationRequestBuilder getAuthenticationRequestBuilder() {
+        return authenticationRequestBuilder;
+    }
+
+    public void setAuthenticationRequestBuilder(AuthenticationRequestBuilder authenticationRequestBuilder) {
+        this.authenticationRequestBuilder = authenticationRequestBuilder;
+    }
+
+    public OAuthClient getOauthClient() {
+        return oauthClient;
+    }
+
+    public void setOauthClient(OAuthClient oauthClient) {
+        this.oauthClient = oauthClient;
+    }
+
+    public void setOauthClient(Client client) {
+        this.oauthClient = new OAuthClient( new OAuthFeignClient(client));
+    }
+
+    public class OAuthFeignClient implements HttpClient {
+
+        private Client client;
+
+        public OAuthFeignClient() {
+            this.client = new Client.Default(null, null);
+        }
+
+        public OAuthFeignClient(Client client) {
+            this.client = client;
+        }
+
+        public <T extends OAuthClientResponse> T execute(OAuthClientRequest request, Map<String, String> headers,
+                String requestMethod, Class<T> responseClass)
+                        throws OAuthSystemException, OAuthProblemException {
+
+            RequestTemplate req = new RequestTemplate()
+                    .append(request.getLocationUri())
+                    .method(requestMethod)
+                    .body(request.getBody());
+
+            for (Entry<String, String> entry : headers.entrySet()) {
+                req.header(entry.getKey(), entry.getValue());
+            }
+            Response feignResponse;
+            String body = "";
+            try {
+                feignResponse = client.execute(req.request(), new Options());
+                body = Util.toString(feignResponse.body().asReader());
+            } catch (IOException e) {
+                throw new OAuthSystemException(e);
+            }
+
+            String contentType = null;
+            Collection<String> contentTypeHeader =  feignResponse.headers().get("Content-Type");
+            if(contentTypeHeader != null) {
+                contentType = StringUtil.join(contentTypeHeader.toArray(new String[0]), ";");
+            }
+
+            return OAuthClientResponseFactory.createCustomResponse(
+                    body,
+                    contentType,
+                    feignResponse.status(),
+                    responseClass
+            );
+        }
+
+        public void shutdown() {
+            // Nothing to do here
+        }
+
+    }
 }

modules/swagger-codegen/src/main/resources/Java/libraries/feign/pom.mustache

@@ -164,6 +164,12 @@
       <version>2.2</version>
     </dependency>
 
+    <dependency>
+      <groupId>org.apache.oltu.oauth2</groupId>
+      <artifactId>org.apache.oltu.oauth2.client</artifactId>
+      <version>${oltu-version}</version>
+    </dependency>
+
     <!-- test dependencies -->
     <dependency>
       <groupId>junit</groupId>
@@ -179,5 +185,6 @@
     <jodatime-version>2.5</jodatime-version>
     <junit-version>4.12</junit-version>
     <maven-plugin-version>1.0.0</maven-plugin-version>
+    <oltu-version>1.0.0</oltu-version>
   </properties>
 </project>

samples/client/petstore/java/feign/pom.xml

@@ -164,6 +164,12 @@
       <version>2.2</version>
     </dependency>
 
+    <dependency>
+      <groupId>org.apache.oltu.oauth2</groupId>
+      <artifactId>org.apache.oltu.oauth2.client</artifactId>
+      <version>${oltu-version}</version>
+    </dependency>
+
     <!-- test dependencies -->
     <dependency>
       <groupId>junit</groupId>
@@ -179,5 +185,6 @@
     <jodatime-version>2.5</jodatime-version>
     <junit-version>4.12</junit-version>
     <maven-plugin-version>1.0.0</maven-plugin-version>
+    <oltu-version>1.0.0</oltu-version>
   </properties>
 </project>

samples/client/petstore/java/feign/src/main/java/io/swagger/client/ApiClient.java

@@ -3,6 +3,9 @@ package io.swagger.client;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.AuthenticationRequestBuilder;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.TokenRequestBuilder;
+
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
@@ -13,8 +16,9 @@ import feign.jackson.JacksonDecoder;
 import feign.jackson.JacksonEncoder;
 import feign.slf4j.Slf4jLogger;
 import io.swagger.client.auth.*;
+import io.swagger.client.auth.OAuth.AccessTokenListener;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class ApiClient {
   public interface Api {}
 
@@ -76,10 +80,32 @@ public class ApiClient {
     this.setCredentials(username,  password);
   }
 
+  /**
+   * Helper constructor for single password oauth2
+   * @param authName
+   * @param clientId
+   * @param secret
+   * @param username
+   * @param password
+   */
+   public ApiClient(String authName, String clientId, String secret, String username, String password) {
+     this(authName);
+     this.getTokenEndPoint()
+            .setClientId(clientId)
+            .setClientSecret(secret)
+            .setUsername(username)
+            .setPassword(password);
+   }
+
   public String getBasePath() {
     return basePath;
   }
 
+  public ApiClient setBasePath(String basePath) {
+    this.basePath = basePath;
+    return this;
+  }
+
   public Map<String, RequestInterceptor> getApiAuthorizations() {
     return apiAuthorizations;
   }
@@ -88,11 +114,6 @@ public class ApiClient {
     this.apiAuthorizations = apiAuthorizations;
   }
 
-  public ApiClient setBasePath(String basePath) {
-    this.basePath = basePath;
-    return this;
-  }
-
   public Feign.Builder getFeignBuilder() {
     return feignBuilder;
   }
@@ -179,8 +200,92 @@ public class ApiClient {
         basicAuth.setCredentials(username, password);
         return;
       }
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.getTokenRequestBuilder().setUsername(username).setPassword(password);
+        return;
+      }
+    }
+    throw new RuntimeException("No Basic authentication or OAuth configured!");
+  }
+
+  /**
+   * Helper method to configure the token endpoint of the first oauth found in the apiAuthorizations (there should be only one)
+   * @return
+   */
+  public TokenRequestBuilder getTokenEndPoint() {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        return oauth.getTokenRequestBuilder();
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Helper method to configure authorization endpoint of the first oauth found in the apiAuthorizations (there should be only one)
+   * @return
+   */
+  public AuthenticationRequestBuilder getAuthorizationEndPoint() {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        return oauth.getAuthenticationRequestBuilder();
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Helper method to pre-set the oauth access token of the first oauth found in the apiAuthorizations (there should be only one)
+   * @param accessToken
+   * @param expiresIn : validity period in seconds
+   */
+  public void setAccessToken(String accessToken, Long expiresIn) {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.setAccessToken(accessToken, expiresIn);
+        return;
+      }
+    }
+  }
+
+  /**
+   * Helper method to configure the oauth accessCode/implicit flow parameters
+   * @param clientId
+   * @param clientSecret
+   * @param redirectURI
+   */
+  public void configureAuthorizationFlow(String clientId, String clientSecret, String redirectURI) {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.getTokenRequestBuilder()
+                .setClientId(clientId)
+                .setClientSecret(clientSecret)
+                .setRedirectURI(redirectURI);
+        oauth.getAuthenticationRequestBuilder()
+                .setClientId(clientId)
+                .setRedirectURI(redirectURI);
+        return;
+      }
+    }
+  }
+
+  /**
+   * Configures a listener which is notified when a new access token is received.
+   * @param accessTokenListener
+   */
+  public void registerAccessTokenListener(AccessTokenListener accessTokenListener) {
+    for(RequestInterceptor apiAuthorization : apiAuthorizations.values()) {
+      if (apiAuthorization instanceof OAuth) {
+        OAuth oauth = (OAuth) apiAuthorization;
+        oauth.registerAccessTokenListener(accessTokenListener);
+        return;
+      }
     }
-    throw new RuntimeException("No Basic authentication configured!");
   }
 
   public RequestInterceptor getAuthorization(String authName) {

samples/client/petstore/java/feign/src/main/java/io/swagger/client/FormAwareEncoder.java

@@ -14,7 +14,7 @@ import feign.codec.EncodeException;
 import feign.codec.Encoder;
 import feign.RequestTemplate;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class FormAwareEncoder implements Encoder {
   public static final String UTF_8 = "utf-8";
   private static final String LINE_FEED = "\r\n";

samples/client/petstore/java/feign/src/main/java/io/swagger/client/StringUtil.java

@@ -1,6 +1,6 @@
 package io.swagger.client;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class StringUtil {
   /**
    * Check if the given array contains the given value (with case-insensitive comparison).

samples/client/petstore/java/feign/src/main/java/io/swagger/client/api/PetApi.java

@@ -8,7 +8,7 @@ import java.io.File;
 import java.util.*;
 import feign.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public interface PetApi extends ApiClient.Api {
 
 

samples/client/petstore/java/feign/src/main/java/io/swagger/client/api/StoreApi.java

@@ -8,7 +8,7 @@ import io.swagger.client.model.Order;
 import java.util.*;
 import feign.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public interface StoreApi extends ApiClient.Api {
 
 

samples/client/petstore/java/feign/src/main/java/io/swagger/client/api/UserApi.java

@@ -8,7 +8,7 @@ import java.util.*;
 import java.util.*;
 import feign.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public interface UserApi extends ApiClient.Api {
 
 

samples/client/petstore/java/feign/src/main/java/io/swagger/client/auth/OAuth.java

@@ -1,17 +1,203 @@
 package io.swagger.client.auth;
 
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.oltu.oauth2.client.HttpClient;
+import org.apache.oltu.oauth2.client.OAuthClient;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.AuthenticationRequestBuilder;
+import org.apache.oltu.oauth2.client.request.OAuthClientRequest.TokenRequestBuilder;
+import org.apache.oltu.oauth2.client.response.OAuthClientResponse;
+import org.apache.oltu.oauth2.client.response.OAuthClientResponseFactory;
+import org.apache.oltu.oauth2.client.response.OAuthJSONAccessTokenResponse;
+import org.apache.oltu.oauth2.common.exception.OAuthProblemException;
+import org.apache.oltu.oauth2.common.exception.OAuthSystemException;
+import org.apache.oltu.oauth2.common.message.types.GrantType;
+import org.apache.oltu.oauth2.common.token.BasicOAuthToken;
+
+import feign.Client;
+import feign.Request.Options;
 import feign.RequestInterceptor;
 import feign.RequestTemplate;
+import feign.Response;
+import feign.Util;
+import io.swagger.client.StringUtil;
+
 
 public class OAuth implements RequestInterceptor {
 
+    public interface AccessTokenListener {
+        public void notify(BasicOAuthToken token);
+    }
+
+    private volatile String accessToken;
+    private Long expirationTimeMillis;
+    private OAuthClient oauthClient;
+    private TokenRequestBuilder tokenRequestBuilder;
+    private AuthenticationRequestBuilder authenticationRequestBuilder;
+    private AccessTokenListener accessTokenListener;
+
+    public OAuth(Client client, TokenRequestBuilder requestBuilder) {
+        setOauthClient(client);
+        this.tokenRequestBuilder = requestBuilder;
+    }
+
+    public OAuth(Client client, OAuthFlow flow, String authorizationUrl, String tokenUrl, String scopes) {
+        this(client, OAuthClientRequest.tokenLocation(tokenUrl).setScope(scopes));
+        setFlow(flow);
+        authenticationRequestBuilder = OAuthClientRequest.authorizationLocation(authorizationUrl);
+    }
+
     public OAuth(OAuthFlow flow, String authorizationUrl, String tokenUrl, String scopes) {
-        // TODO Not implemented yet
+        this(new Client.Default(null, null), flow, authorizationUrl, tokenUrl, scopes);
+    }
+
+    public void setFlow(OAuthFlow flow) {
+        switch(flow) {
+        case accessCode:
+        case implicit:
+            tokenRequestBuilder.setGrantType(GrantType.AUTHORIZATION_CODE);
+            break;
+        case password:
+            tokenRequestBuilder.setGrantType(GrantType.PASSWORD);
+            break;
+        case application:
+            tokenRequestBuilder.setGrantType(GrantType.CLIENT_CREDENTIALS);
+            break;
+        default:
+            break;
+        }
     }
 
     @Override
     public void apply(RequestTemplate template) {
-        // TODO Not implemented yet
+        // If the request already have an authorization (eg. Basic auth), do nothing
+        if (template.headers().containsKey("Authorization")) {
+            return;
+        }
+        // If first time, get the token
+        if (expirationTimeMillis == null || System.currentTimeMillis() >= expirationTimeMillis) {
+            try {
+                updateAccessToken();
+            } catch (OAuthSystemException e) {
+                e.printStackTrace();
+                return;
+            } catch (OAuthProblemException e) {
+                e.printStackTrace();
+                return;
+            }
+        }
+        if (getAccessToken() != null) {
+            template.header("Authorization", "Bearer " + getAccessToken());
+        }
     }
 
+    public synchronized void updateAccessToken() throws OAuthSystemException, OAuthProblemException {
+        if (getAccessToken() == null) {
+            OAuthJSONAccessTokenResponse accessTokenResponse = oauthClient.accessToken(tokenRequestBuilder.buildBodyMessage());
+            if (accessTokenResponse != null && accessTokenResponse.getAccessToken() != null) {
+                setAccessToken(accessTokenResponse.getAccessToken(), accessTokenResponse.getExpiresIn());
+                if (accessTokenListener != null) {
+                    accessTokenListener.notify((BasicOAuthToken) accessTokenResponse.getOAuthToken());
+                }
+            }
+        }
+    }
+
+    public void registerAccessTokenListener(AccessTokenListener accessTokenListener) {
+        this.accessTokenListener = accessTokenListener;
+    }
+
+    public synchronized String getAccessToken() {
+        return accessToken;
+    }
+
+    public synchronized void setAccessToken(String accessToken, Long expiresIn) {
+        this.accessToken = accessToken;
+        this.expirationTimeMillis = System.currentTimeMillis() + expiresIn * 1000;
+    }
+
+    public TokenRequestBuilder getTokenRequestBuilder() {
+        return tokenRequestBuilder;
+    }
+
+    public void setTokenRequestBuilder(TokenRequestBuilder tokenRequestBuilder) {
+        this.tokenRequestBuilder = tokenRequestBuilder;
+    }
+
+    public AuthenticationRequestBuilder getAuthenticationRequestBuilder() {
+        return authenticationRequestBuilder;
+    }
+
+    public void setAuthenticationRequestBuilder(AuthenticationRequestBuilder authenticationRequestBuilder) {
+        this.authenticationRequestBuilder = authenticationRequestBuilder;
+    }
+
+    public OAuthClient getOauthClient() {
+        return oauthClient;
+    }
+
+    public void setOauthClient(OAuthClient oauthClient) {
+        this.oauthClient = oauthClient;
+    }
+
+    public void setOauthClient(Client client) {
+        this.oauthClient = new OAuthClient( new OAuthFeignClient(client));
+    }
+
+    public class OAuthFeignClient implements HttpClient {
+
+        private Client client;
+
+        public OAuthFeignClient() {
+            this.client = new Client.Default(null, null);
+        }
+
+        public OAuthFeignClient(Client client) {
+            this.client = client;
+        }
+
+        public <T extends OAuthClientResponse> T execute(OAuthClientRequest request, Map<String, String> headers,
+                String requestMethod, Class<T> responseClass)
+                        throws OAuthSystemException, OAuthProblemException {
+
+            RequestTemplate req = new RequestTemplate()
+                    .append(request.getLocationUri())
+                    .method(requestMethod)
+                    .body(request.getBody());
+
+            for (Entry<String, String> entry : headers.entrySet()) {
+                req.header(entry.getKey(), entry.getValue());
+            }
+            Response feignResponse;
+            String body = "";
+            try {
+                feignResponse = client.execute(req.request(), new Options());
+                body = Util.toString(feignResponse.body().asReader());
+            } catch (IOException e) {
+                throw new OAuthSystemException(e);
+            }
+
+            String contentType = null;
+            Collection<String> contentTypeHeader =  feignResponse.headers().get("Content-Type");
+            if(contentTypeHeader != null) {
+                contentType = StringUtil.join(contentTypeHeader.toArray(new String[0]), ";");
+            }
+
+            return OAuthClientResponseFactory.createCustomResponse(
+                    body,
+                    contentType,
+                    feignResponse.status(),
+                    responseClass
+            );
+        }
+
+        public void shutdown() {
+            // Nothing to do here
+        }
+
+    }
 }

samples/client/petstore/java/feign/src/main/java/io/swagger/client/model/Category.java

@@ -10,7 +10,7 @@ import io.swagger.annotations.ApiModelProperty;
 
 
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class Category   {
   
   private Long id = null;

samples/client/petstore/java/feign/src/main/java/io/swagger/client/model/Order.java

@@ -11,7 +11,7 @@ import java.util.Date;
 
 
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class Order   {
   
   private Long id = null;

samples/client/petstore/java/feign/src/main/java/io/swagger/client/model/Pet.java

@@ -13,7 +13,7 @@ import java.util.*;
 
 
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class Pet   {
   
   private Long id = null;

samples/client/petstore/java/feign/src/main/java/io/swagger/client/model/Tag.java

@@ -10,7 +10,7 @@ import io.swagger.annotations.ApiModelProperty;
 
 
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class Tag   {
   
   private Long id = null;

samples/client/petstore/java/feign/src/main/java/io/swagger/client/model/User.java

@@ -10,7 +10,7 @@ import io.swagger.annotations.ApiModelProperty;
 
 
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-09T15:18:34.525Z")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2016-01-11T21:48:33.457Z")
 public class User   {
   
   private Long id = null;