spring boot / cloud (八) 使用RestTemplate来构建远程调用服务

前言

上周因家里突发急事,请假一周,故博客没有正常更新

RestTemplate介绍:

RestTemplate是spring框架中自带的rest客户端工具类,具有丰富的API,并且在spring cloud中,标记@LoadBalanced注解,可以实现客户端负载均衡的rest调用.

思路

RestTemplate虽然提供了丰富的API,但是这些API过于底层,如果不稍加控制,让开发人员随意使用,那后续的代码也将会变的五花八门,难以维护.

同时,当系统规模大了之后,将会有更多的服务,并且服务之间的调用关系也将更加复杂,如果不进行管控治理的话,同样,项目同期也将越来越不可控,

最后,服务间调用也需要有明确的权限认证机制,最好是能通过配置的方式来明确,哪些服务可以调用那些服务.从而来把控项目的复杂度.

本文将从以下几点来提供一个解决问题的思路:

通过spring boot的@ConfigurationProperties机制来定义远程服务的元数据,从而实现权限认证的配置化
使用HandlerInterceptor来进行拦截,实现权限的验证
定义通用Rms类,来规范RestTemplate的使用

实现

1.实现权限配置

1.定义Application元数据

public class ApplicationMeta implements Serializable {
  //ID
  private static final long serialVersionUID = 1L;
  //服务ID
  private String serviceId;
  //私钥
  private String secret;
  //权限
  private String purview;
  //所有服务的调用权限(优先判定)
  private Boolean all = false;
  //禁止服务调用
  private Boolean disabled = false;
  //描述
  private String description;
}

2.定义Service元数据

public class ServiceMeta implements Serializable {
  //ID
  private static final long serialVersionUID = 1L;
  //应用名称
  private String owner;
  //地址
  private String uri;
  //服务方法
  private String method;
  //是否HTTPS
  private Boolean isHttps = false;
  //描述
  private String description;

3.定义RmsProperties类

@Component
@ConfigurationProperties(prefix = "org.itkk.rms.properties")
public class RmsProperties implements Serializable {
  //ID
  private static final long serialVersionUID = 1L;
  //应用清单(应用名称 : 应用地址)
  private Map<String, ApplicationMeta> application;
  //服务路径(服务编号 : 服务元数据)
  private Map<String, ServiceMeta> service;

4.在properties文件中进行配置

#定义了一个叫udf-demo(跟spring boot的应用ID一致),设置了私钥,以及可调用的服务
org.itkk.rms.properties.application.udf-demo.serviceId=127.0.0.1:8080
org.itkk.rms.properties.application.udf-demo.secret=ADSFHKW349546RFSGF
org.itkk.rms.properties.application.udf-demo.purview=FILE_3
org.itkk.rms.properties.application.udf-demo.all=false
org.itkk.rms.properties.application.udf-demo.disabled=false
org.itkk.rms.properties.application.udf-demo.description=sample application

#定义了一个叫FILE_3的服务,后续使用这个服务编号进行调用即可
org.itkk.rms.properties.service.FILE_3.owner=udf-demo
org.itkk.rms.properties.service.FILE_3.uri=/service/file/download
org.itkk.rms.properties.service.FILE_3.method=POST
org.itkk.rms.properties.service.FILE_3.isHttps=false
org.itkk.rms.properties.service.FILE_3.description=文件下载

2.实现权限校验

1.定义RmsAuthHandlerInterceptor拦截器

public class RmsAuthHandlerInterceptor implements HandlerInterceptor {
  //环境标识
  private static final String DEV_PROFILES = "dev";
  //配置
  @Autowired
  private RmsProperties rmsProperties;
  //环境变量
  @Autowired
  private Environment env;
  
  @Override
  public boolean preHandle(HttpServletRequest request, 
      HttpServletResponse response,
      Object handler) {
      
      .......
      
  }
}

2.完善preHandle方法-取出认证信息

    String rmsApplicationName = request.getHeader(Constant.HEADER_RMS_APPLICATION_NAME_CODE);
    if (StringUtils.isBlank(rmsApplicationName)) {
      rmsApplicationName = request.getParameter(Constant.HEADER_RMS_APPLICATION_NAME_CODE);
    }
    //获取认证信息(sign)
    String rmsSign = request.getHeader(Constant.HEADER_RMS_SIGN_CODE);
    if (StringUtils.isBlank(rmsSign)) {
      rmsSign = request.getParameter(Constant.HEADER_RMS_SIGN_CODE);
    }
    //获取认证信息(服务代码)
    String rmsServiceCode = request.getHeader(Constant.HEADER_SERVICE_CODE_CODE);
    if (StringUtils.isBlank(rmsServiceCode)) {
      rmsServiceCode = request.getParameter(Constant.HEADER_SERVICE_CODE_CODE);
    }
    //获取请求地址
    String url = request.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE).toString();
    //获取请求方法
    String method = request.getMethod();

3.完善preHandle方法-校验

    //判断环境(开发环境无需校验)
    if (!DEV_PROFILES.equals(env.getProperty("spring.profiles.active"))) {
      //判断是否缺少认证信息
      if (StringUtils.isBlank(rmsApplicationName) || StringUtils.isBlank(rmsSign)
          || StringUtils.isBlank(rmsServiceCode)) {
        throw new AuthException("missing required authentication parameters (rmsApplicationName , rmsSign)");
      }
      //判断systemTag是否有效
      if (!this.rmsProperties.getApplication().containsKey(rmsApplicationName)) {
        throw new AuthException("unrecognized systemTag:" + rmsApplicationName);
      }
      //获得应用元数据
      ApplicationMeta applicationMeta = rmsProperties.getApplication().get(rmsApplicationName);
      //获得secret
      String secret = applicationMeta.getSecret();
      //计算sign
      String sign = Constant.sign(rmsApplicationName, secret);
      //比较sign
      if (!rmsSign.equals(sign)) {
        throw new AuthException("sign Validation failed");
      }
      //判断是否有调用所有服务的权限
      if (!applicationMeta.getAll()) {
        //判断是否禁止调用所有服务权限
        if (applicationMeta.getDisabled()) {
          throw new PermissionException(rmsApplicationName + " is disabled");
        }
        //判断是否有调用该服务的权限
        if (applicationMeta.getPurview().indexOf(rmsServiceCode) == -1) {
          throw new PermissionException("no access to this servoceCode : " + rmsServiceCode);
        }
        //判断服务元数据是否存在
        if (!rmsProperties.getService().containsKey(rmsServiceCode)) {
          throw new PermissionException("service code not exist");
        }
        //获得服务元数据
        ServiceMeta serviceMeta = rmsProperties.getService().get(rmsServiceCode);
        //比较url和method的有效性
        if (!serviceMeta.getUri().equals(url) || !serviceMeta.getMethod().equals(method)) {
          throw new PermissionException("url and method verification error");
        }
      }
    }

4.定义RmsConfig类

@Configuration
@ConfigurationProperties(prefix = "org.itkk.rms.config")
@Validated
public class RmsConfig {

  //RMS扫描路径
  @NotNull
  private String rmsPathPatterns;

  .........
  
}

5.定义RmsConfig类-注册bean

  @Bean
  @LoadBalanced
  RestTemplate restTemplate(ClientHttpRequestFactory requestFactory) {
    return new RestTemplate(requestFactory);
  }
  
  @Bean
  public RmsAuthHandlerInterceptor rmsAuthHandlerInterceptor() {
    return new RmsAuthHandlerInterceptor();
  }
  
  @Bean
  public WebMvcConfigurer rmsAuthConfigurer() { //NOSONAR
    return new WebMvcConfigurerAdapter() {
      @Override
      public void addInterceptors(InterceptorRegistry registry) {
        String[] rmsPathPatternsArray = rmsPathPatterns.split(",");
        registry.addInterceptor(rmsAuthHandlerInterceptor()).addPathPatterns(rmsPathPatternsArray);
        super.addInterceptors(registry);
      }
    };
  }

6.在properties文件中进行配置

#拦截路径
org.itkk.rms.config.rmsPathPatterns=/service/**

3.实现Rms类

1.定义rms类

@Component
public class Rms {
  //应用名称
  @Value("${spring.application.name}")
  private String springApplicationName;
  //restTemplate
  @Autowired
  private RestTemplate restTemplate;
  //配置
  @Autowired
  private RmsProperties rmsProperties;

2.定义rms类-call方法

  public <I, O> ResponseEntity<O> call(String serviceCode, I input, String uriParam,
      ParameterizedTypeReference<O> responseType, Map<String, ?> uriVariables) {
    //客户端权限验证
    verification(serviceCode);
    //构建请求路径
    String path = getRmsUrl(serviceCode);
    //获得请求方法
    String method = getRmsMethod(serviceCode);
    //拼装路径参数
    if (StringUtils.isNotBlank(uriParam)) {
      path += uriParam;
    }
    //构建请求头
    HttpHeaders httpHeaders = buildSystemTagHeaders(serviceCode);
    //构建请求消息体
    HttpEntity<I> requestEntity = new HttpEntity<>(input, httpHeaders);
    //请求并且返回
    return restTemplate.exchange(path, HttpMethod.resolve(method), requestEntity, responseType,
        uriVariables != null ? uriVariables : new HashMap<String, String>());
  }

3.定义rms类-其他方法

  //构建请求头
  private HttpHeaders buildSystemTagHeaders(String serviceCode) {
    String secret = rmsProperties.getApplication().get(springApplicationName).getSecret();
    HttpHeaders headers = new HttpHeaders();
    headers.add(Constant.HEADER_RMS_APPLICATION_NAME_CODE, springApplicationName);
    headers.add(Constant.HEADER_RMS_SIGN_CODE, Constant.sign(springApplicationName, secret));
    headers.add(Constant.HEADER_SERVICE_CODE_CODE, serviceCode);
    return headers;
  }
  //客户端验证
  private void verification(String serviceCode) {
    ApplicationMeta applicationMeta = rmsProperties.getApplication().get(springApplicationName);
    if (!applicationMeta.getAll()) {
      if (applicationMeta.getDisabled()) {
        throw new PermissionException(springApplicationName + " is disabled");
      }
      if (applicationMeta.getPurview().indexOf(serviceCode) == -1) {
        throw new PermissionException("no access to this servoceCode : " + serviceCode);
      }
    }
  }
  //获得请求方法
  private String getRmsMethod(String serviceCode) {
    return rmsProperties.getService().get(serviceCode).getMethod();
  }
  //构造url
  private String getRmsUrl(String serviceCode) {
    //获取服务元数据
    ServiceMeta serviceMeta = rmsProperties.getService().get(serviceCode);
    //构建请求路径
    StringBuilder url =
        new StringBuilder(serviceMeta.getIsHttps() ? Constant.HTTPS : Constant.HTTP);
    url.append(rmsProperties.getApplication().get(serviceMeta.getOwner()).getServiceId());
    url.append(serviceMeta.getUri());
    return url.toString();
  }
  //计算sign
  public static String sign(String rmsApplicationName, String secret) {
    final String split = "_";
    StringBuilder sb = new StringBuilder();
    sb.append(rmsApplicationName).append(split).append(secret).append(split)
        .append(new SimpleDateFormat(DATA_FORMAT).format(new Date()));
    return DigestUtils.md5Hex(sb.toString());
  }

3.客户端调用

//获得文件信息
ResponseEntity<RestResponse<FileInfo>> fileInfo = rms.call("FILE_4", fileParam, null,
              new ParameterizedTypeReference<RestResponse<FileInfo>>() {
              }, null);