在@ dmitri-algazin之后，您可以实现工作流，基本上有两个选择：

1. 如果您想涵盖Keycloak之外的其他IDM，该解决方案以某种方式解决了“ 单一职责”原则，我会使用RestTemplate。在下面可以找到变量：

   //Constants
   @Value("${keycloak.url}")
   private String keycloakUrl;
   
   @Value("${keycloak.realm}")
   private String keycloakRealm;
   
   @Value("${keycloak.client_id}")
   private String keycloakClientId;
   
   RestTemplate restTemplate = new RestTemplate();
   private static final String BEARER = "BEARER ";
   

首先，您需要生成访问令牌：

    @Override
    public AccessTokenResponse login(KeycloakUser user) throws NotAuthorizedException {
        try {
            String uri = keycloakUrl + "/realms/" + keycloakRealm + 
                    "/protocol/openid-connect/token";
            String data = "grant_type=password&username="+
                    user.getUsername()+"&password="+user.getPassword()+"&client_id="+
                    keycloakClientId;

            HttpHeaders headers = new HttpHeaders();
            headers.set("Content-Type", "application/x-www-form-urlencoded");

            HttpEntity<String> entity = new HttpEntity<String>(data, headers);
            ResponseEntity<AccessTokenResponse> response = restTemplate.exchange(uri, 
                    HttpMethod.POST, entity, AccessTokenResponse.class);

            if (response.getStatusCode().value() != HttpStatus.SC_OK) {
                log.error("Unauthorised access to protected resource", response.getStatusCode().value());
                throw new NotAuthorizedException("Unauthorised access to protected resource");
            }
            return response.getBody();
        } catch (Exception ex) {
            log.error("Unauthorised access to protected resource", ex);
            throw new NotAuthorizedException("Unauthorised access to protected resource");
        } 
    }

然后，使用令牌可以从用户检索信息：

    @Override
    public String user(String authToken) throws NotAuthorizedException {

        if (! authToken.toUpperCase().startsWith(BEARER)) {
            throw new NotAuthorizedException("Invalid OAuth Header. Missing Bearer prefix");
        }

        HttpHeaders headers = new HttpHeaders();
        headers.set("Authorization", authToken);

        HttpEntity<String> entity = new HttpEntity<>(headers);

        ResponseEntity<AccessToken> response = restTemplate.exchange(
                keycloakUrl + "/realms/" + keycloakRealm + "/protocol/openid-connect/userinfo", 
                HttpMethod.POST, 
                entity, 
                AccessToken.class);

        if (response.getStatusCode().value() != HttpStatus.SC_OK) {
            log.error("OAuth2 Authentication failure. "
                    + "Invalid OAuth Token supplied in Authorization Header on Request. Code {}", response.getStatusCode().value());
            throw new NotAuthorizedException("OAuth2 Authentication failure. "
                    + "Invalid OAuth Token supplied in Authorization Header on Request.");
        }

        log.debug("User info: {}", response.getBody().getPreferredUsername());
        return response.getBody().getPreferredUsername();
    }

您可以将该URL替换为@ dimitri-algazin提供的URL，以检索所有用户信息。

1. 可以使用Keycloak依赖项：

       <!-- keycloak -->
       <dependency>
           <groupId>org.keycloak</groupId>
           <artifactId>keycloak-admin-client</artifactId>
           <version>3.4.3.Final</version>
       </dependency>
   
       <dependency>
           <groupId>org.jboss.resteasy</groupId>
           <artifactId>resteasy-client</artifactId>
           <version>3.1.4.Final</version>
       </dependency>
   

并使用这些类来生成令牌：

            Keycloak keycloak = KeycloakBuilder
                    .builder()
                    .serverUrl(keycloakUrl)
                    .realm(keycloakRealm)
                    .username(user.getUsername())
                    .password(user.getPassword())
                    .clientId(keycloakClientId)
                    .resteasyClient(new ResteasyClientBuilder().connectionPoolSize(10).build())
                    .build();

            return keycloak.tokenManager().getAccessToken();

例子摘自这里。我们还将映像上传到Docker
Hub，以促进与Keycloak的交互。因此，我们从选项2）开始。目前，我们正在涵盖其他IdM，我们选择了选项1），以避免包括额外的依赖项。结论：

如果您坚持使用Keycloak，我会 选择选项2 ，因为类包含Keycloak工具的额外功能。我会 选择选项1
进行进一步介绍，并使用其他OAuth 2.0工具。