keycloak提供了jwks服务，其地址可以在/auth/realms/fabao/.well-known/openid-configuration的返回结果中找到，jwks_uri它表示了公钥的颁发者，可以使用颁发出来的公钥来验证token的签名，基地址也是固定的/auth/realms/fabao/protocol/openid-connect/certs。

springboot构建keycloak的token校验服务

依赖包

jwt的解析以来于java-jwt包，由jwks服务解析依赖于jwks-rsa包，jwks是什么，可以看这里

   <dependencyManagement>
      <dependencies>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-parent</artifactId>
              <version>${spring-boot-dependencies.version}</version>
              <type>pom</type>
              <scope>import</scope>
          </dependency>
          <dependency>
              <groupId>org.keycloak.bom</groupId>
              <artifactId>keycloak-adapter-bom</artifactId>
              <version>14.0.0</version>
              <type>pom</type>
              <scope>import</scope>
          </dependency>
      </dependencies>
  </dependencyManagement>

  <dependencies>
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-web</artifactId>
      </dependency>
      <!-- keycloak -->
      <dependency>
          <groupId>org.keycloak</groupId>
          <artifactId>keycloak-spring-boot-starter</artifactId>
      </dependency>
       <!-- jwt -->
      <dependency>
          <groupId>com.auth0</groupId>
          <artifactId>java-jwt</artifactId>
          <version>3.11.0</version>
      </dependency>
      <dependency>
          <groupId>com.auth0</groupId>
          <artifactId>jwks-rsa</artifactId>
          <version>0.12.0</version>
      </dependency>
  </dependencies>

相关配置

keycloak:
    realm: fabao
    resource: pkulaw
    client-key-password: c0b7ab8e-485b-4a10-bff8-7c7d3f472096
    auth-server-url: http://192.168.xx.xx:8080/auth/realms/fabao/protocol/openid-connect/auth
kc:
  jwk-set-uri: http://192.168.xx.xx:8080/auth/realms/fabao/protocol/openid-connect/certs
  certs-id: E_6ih35yTLJMieI0vqg9MmTQrJ6RcUSxiXeNdcMaoYk

jwks服务

@Service
public class JwtService {

    @Value("${kc.jwk-set-uri}")
    private String jwksUrl;

    @Value("${kc.certs-id}")
    private String certsId;

    @Cacheable(value = "jwkCache")
    public Jwk getJwk() throws Exception {
        return new UrlJwkProvider(new URL(jwksUrl)).get(certsId);
    }
}

校验token

这只是个简单的demo，真实项目中，这种校验的代码应该写在拦截器中，统一进行处理

 @GetMapping("/teacher")
  public HashMap teacher(@RequestHeader("Authorization") String authHeader) {
    try {
        DecodedJWT jwt = JWT.decode(authHeader.replace("Bearer", "").trim());

        // check JWT is valid
        Jwk jwk = jwtService.getJwk();
        Algorithm algorithm = Algorithm.RSA256((RSAPublicKey) jwk.getPublicKey(), null);

        algorithm.verify(jwt);

        // check JWT role is correct
        List<String> roles = ((List)jwt.getClaim("realm_access").asMap().get("roles"));
        if(!roles.contains("teacher"))
            throw new Exception("not a teacher role");

        // check JWT is still active
        Date expiryDate = jwt.getExpiresAt();
        if(expiryDate.before(new Date()))
            throw new Exception("token is expired");

        // all validation passed
        return new HashMap() {{
            put("role", "teacher");
        }};
    } catch (Exception e) {
        logger.error("exception : {} ", e.getMessage());
        return new HashMap() {{
            put("status", "forbidden");
        }};
    }
}

{
  "keys": [
    {
      "kty": "RSA",
      "kid": "123",
      "use": "sig",
      "alg": "RS256",
      "n": "public_key_value",
      "e": "AQAB"
    }
  ]
}