spring boot / cloud (八) 使用RestTemplate來構建遠程調用服務

spring boot / cloud (八) 使用RestTemplate來構建遠程調用服務

前言

上週因家裏突發急事,請假一週,故博客沒有正常更新

RestTemplate介紹:

RestTemplate是spring框架中自帶的rest客戶端工具類,具備豐富的API,而且在spring cloud中,標記@LoadBalanced註解,能夠實現客戶端負載均衡的rest調用.

思路

RestTemplate雖然提供了豐富的API,可是這些API過於底層,若是不稍加控制,讓開發人員隨意使用,那後續的代碼也將會變的五花八門,難以維護.

同時,當系統規模大了以後,將會有更多的服務,而且服務之間的調用關係也將更加複雜,若是不進行管控治理的話,一樣,項目同期也將愈來愈不可控,

最後,服務間調用也須要有明確的權限認證機制,最好是能經過配置的方式來明確,哪些服務能夠調用那些服務.從而來把控項目的複雜度.

本文將從如下幾點來提供一個解決問題的思路:

• 經過spring boot的@ConfigurationProperties機制來定義遠程服務的元數據,從而實現權限認證的配置化

• 使用HandlerInterceptor來進行攔截,實現權限的驗證

• 定義通用Rms類,來規範RestTemplate的使用

實現

1.實現權限配置

1.定義Application元數據

public class ApplicationMeta implements Serializable {
  //ID
  private static final long serialVersionUID = 1L;
  //服務ID
  private String serviceId;
  //私鑰
  private String secret;
  //權限
  private String purview;
  //全部服務的調用權限(優先斷定)
  private Boolean all = false;
  //禁止服務調用
  private Boolean disabled = false;
  //描述
  private String description;
}

2.定義Service元數據

public class ServiceMeta implements Serializable {
  //ID
  private static final long serialVersionUID = 1L;
  //應用名稱
  private String owner;
  //地址
  private String uri;
  //服務方法
  private String method;
  //是否HTTPS
  private Boolean isHttps = false;
  //描述
  private String description;

3.定義RmsProperties類

@Component
@ConfigurationProperties(prefix = "org.itkk.rms.properties")
public class RmsProperties implements Serializable {
  //ID
  private static final long serialVersionUID = 1L;
  //應用清單(應用名稱 : 應用地址)
  private Map<String, ApplicationMeta> application;
  //服務路徑(服務編號 : 服務元數據)
  private Map<String, ServiceMeta> service;

4.在properties文件中進行配置

#定義了一個叫udf-demo(跟spring boot的應用ID一致),設置了私鑰,以及可調用的服務
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

#定義了一個叫FILE_3的服務,後續使用這個服務編號進行調用便可
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=文件下載

2.實現權限校驗

1.定義RmsAuthHandlerInterceptor攔截器

public class RmsAuthHandlerInterceptor implements HandlerInterceptor {
  //環境標識
  private static final String DEV_PROFILES = "dev";
  //配置
  @Autowired
  private RmsProperties rmsProperties;
  //環境變量
  @Autowired
  private Environment env;
  
  @Override
  public boolean preHandle(HttpServletRequest request, 
      HttpServletResponse response,
      Object handler) {
      
      .......
      
  }
}

2.完善preHandle方法-取出認證信息

String rmsApplicationName = request.getHeader(Constant.HEADER_RMS_APPLICATION_NAME_CODE);
    if (StringUtils.isBlank(rmsApplicationName)) {
      rmsApplicationName = request.getParameter(Constant.HEADER_RMS_APPLICATION_NAME_CODE);
    }
    //獲取認證信息(sign)
    String rmsSign = request.getHeader(Constant.HEADER_RMS_SIGN_CODE);
    if (StringUtils.isBlank(rmsSign)) {
      rmsSign = request.getParameter(Constant.HEADER_RMS_SIGN_CODE);
    }
    //獲取認證信息(服務代碼)
    String rmsServiceCode = request.getHeader(Constant.HEADER_SERVICE_CODE_CODE);
    if (StringUtils.isBlank(rmsServiceCode)) {
      rmsServiceCode = request.getParameter(Constant.HEADER_SERVICE_CODE_CODE);
    }
    //獲取請求地址
    String url = request.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE).toString();
    //獲取請求方法
    String method = request.getMethod();

3.完善preHandle方法-校驗

//判斷環境(開發環境無需校驗)
    if (!DEV_PROFILES.equals(env.getProperty("spring.profiles.active"))) {
      //判斷是否缺乏認證信息
      if (StringUtils.isBlank(rmsApplicationName) || StringUtils.isBlank(rmsSign)
          || StringUtils.isBlank(rmsServiceCode)) {
        throw new AuthException("missing required authentication parameters (rmsApplicationName , rmsSign)");
      }
      //判斷systemTag是否有效
      if (!this.rmsProperties.getApplication().containsKey(rmsApplicationName)) {
        throw new AuthException("unrecognized systemTag:" + rmsApplicationName);
      }
      //得到應用元數據
      ApplicationMeta applicationMeta = rmsProperties.getApplication().get(rmsApplicationName);
      //得到secret
      String secret = applicationMeta.getSecret();
      //計算sign
      String sign = Constant.sign(rmsApplicationName, secret);
      //比較sign
      if (!rmsSign.equals(sign)) {
        throw new AuthException("sign Validation failed");
      }
      //判斷是否有調用全部服務的權限
      if (!applicationMeta.getAll()) {
        //判斷是否禁止調用全部服務權限
        if (applicationMeta.getDisabled()) {
          throw new PermissionException(rmsApplicationName + " is disabled");
        }
        //判斷是否有調用該服務的權限
        if (applicationMeta.getPurview().indexOf(rmsServiceCode) == -1) {
          throw new PermissionException("no access to this servoceCode : " + rmsServiceCode);
        }
        //判斷服務元數據是否存在
        if (!rmsProperties.getService().containsKey(rmsServiceCode)) {
          throw new PermissionException("service code not exist");
        }
        //得到服務元數據
        ServiceMeta serviceMeta = rmsProperties.getService().get(rmsServiceCode);
        //比較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.定義RmsConfig類

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

  //RMS掃描路徑
  @NotNull
  private String rmsPathPatterns;

  .........
  
}

5.定義RmsConfig類-註冊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文件中進行配置

#攔截路徑
org.itkk.rms.config.rmsPathPatterns=/service/**

3.實現Rms類

1.定義rms類

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

2.定義rms類-call方法

public <I, O> ResponseEntity<O> call(String serviceCode, I input, String uriParam,
      ParameterizedTypeReference<O> responseType, Map<String, ?> uriVariables) {
    //客戶端權限驗證
    verification(serviceCode);
    //構建請求路徑
    String path = getRmsUrl(serviceCode);
    //得到請求方法
    String method = getRmsMethod(serviceCode);
    //拼裝路徑參數
    if (StringUtils.isNotBlank(uriParam)) {
      path += uriParam;
    }
    //構建請求頭
    HttpHeaders httpHeaders = buildSystemTagHeaders(serviceCode);
    //構建請求消息體
    HttpEntity<I> requestEntity = new HttpEntity<>(input, httpHeaders);
    //請求而且返回
    return restTemplate.exchange(path, HttpMethod.resolve(method), requestEntity, responseType,
        uriVariables != null ? uriVariables : new HashMap<String, String>());
  }

3.定義rms類-其餘方法

//構建請求頭
  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;
  }
  //客戶端驗證
  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);
      }
    }
  }
  //得到請求方法
  private String getRmsMethod(String serviceCode) {
    return rmsProperties.getService().get(serviceCode).getMethod();
  }
  //構造url
  private String getRmsUrl(String serviceCode) {
    //獲取服務元數據
    ServiceMeta serviceMeta = rmsProperties.getService().get(serviceCode);
    //構建請求路徑
    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();
  }
  //計算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.客戶端調用

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

代碼倉庫 (博客配套代碼)

• udf-starter : 基礎項目,腳手架,框架

• udf-sample : 集成樣例

結束

這樣,規範了遠程服務的調用,只關心接口編號和接口的入參和出參,可以增長溝通效率,而且也有了輕量級的服務治理機制,服務間的調用更可控,到最後,配置文件一拉出來一清二楚.

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