HttpMethod自定義失敗重連

541732025發表於2014-12-04
HTTP

我們做web開發時，需要經常使用httpclient來請求http服務，有時為了安全起見，服務提供方會提供多個http地址，這樣如果我們請求某個ip出現異常，可以重試其他的ip地址，來儘量保證系統的穩定，以下是自定義一個HttpMethod重試機制的簡要程式碼。

HostCluster類定義需要連線的協議、ips[]、重試次數、隨機獲取一個host等：

點選(此處)摺疊或開啟

  1. public class HostCluster {
  2.     protected static final String HTTP_PROTOCOL = \"http\";
  3.     protected static final String HTTPS_PROTOCOL = \"https\";

  5.     protected String protocol;
  6.     protected String[] ips; //contain ip and port

  8.     private int idx;
  9.     private int retry;

  11.     private Random random;

  13.     public HostCluster(String ipAndPort) {
  14.         this(HTTP_PROTOCOL, ipAndPort);
  15.     }

  17.     public HostCluster(String protocol, String ipAndPort) {
  18.         this(protocol, ipAndPort, 0);
  19.     }

  21.     public HostCluster(String protocol, String ipAndPort, int retry) {
  22.         if (StringUtils.isEmpty(ipAndPort)) {
  23.             throw new IllegalArgumentException(\"invalid constructor params.\");
  24.         }
  25.         if (retry < 0) {
  26.             throw new IllegalArgumentException(\"invalid retry.\");
  27.         }
  28.         if (!HTTP_PROTOCOL.equals(protocol) && !HTTPS_PROTOCOL.equals(protocol)) {
  29.             throw new IllegalArgumentException(\"invalid protocol.\");
  30.         }
  31.         
  32.         //split the string
  33.         String[] splitStr = StringUtils.split(ipAndPort, \",\");

  35.         this.protocol = protocol;
  36.         this.ips = splitStr;
  37.         this.retry = retry;

  39.         this.idx = this.ips.length;
  40.         this.random = new Random();
  41.     }

  43.     public String randomHost() {
  44.         int index = this.random.nextInt(idx);
  45.         log.info(\"randomIp=\" + ips[index]);
  46.         return this.protocol + \"://\" + ips[index];
  47.     }

  49.     public boolean isHttps() {
  50.         return HTTPS_PROTOCOL.equals(protocol);
  51.     }

  53.     public String getProtocol() {
  54.         return protocol;
  55.     }

  57.     public int getRetry() {
  58.         return retry;
  59.     }
  60. }


ClusterRetryHttpMethod從HostCluster獲取的randomHost，然後new URI()設定相應的base（GetMethod or PostMethod）

點選(此處)摺疊或開啟

  1. public abstract class ClusterRetryHttpMethod<T extends HttpMethod> {
  2.     protected HostCluster cluster;
  3.     protected String urlSuffix;
  4.     protected T base;
  5.     private Integer retry;

  7.     public ClusterRetryHttpMethod(HostCluster cluster, String urlSuffix) {
  8.         this(cluster, urlSuffix, null);
  9.     }

  11.     public ClusterRetryHttpMethod(HostCluster cluster, String urlSuffix, Integer retry) {
  12.         if (cluster == null || StringUtils.isBlank(urlSuffix)) {
  13.             throw new IllegalArgumentException(\"invalid params.\");
  14.         }
  15.         if (retry != null) {
  16.             if (retry < 0) {
  17.                 throw new IllegalArgumentException(\"invalid retry.\");
  18.             } else {
  19.                 this.retry = retry;
  20.             }
  21.         }
  22.         this.cluster = cluster;
  23.         this.urlSuffix = urlSuffix;

  25.         this.base = initBase();
  26.     }

  28.     public boolean isHttps() {
  29.         return this.cluster.isHttps();
  30.     }

  32.     public void setQueryString(String queryString) {
  33.         this.base.setQueryString(queryString);
  34.     }

  36.     public void setQueryString(NameValuePair[] params) {
  37.         this.base.setQueryString(params);
  38.     }

  40.     public int getRetry() {
  41.         return retry == null ? this.cluster.getRetry() : retry;
  42.     }

  44.     protected abstract T initBase();//子類各自實現，GetMethod or PostMethod

  46.     public T randomMethod() throws Exception {
  47.         String url = this.randomUrl();
  48.         if (StringUtils.isBlank(url)) {
  49.             url = \"/\";
  50.         }

  52.         this.base.setURI(new URI(url, true));
  53.         return base;
  54.     }

  56.     protected String randomUrl() {
  57.         return cluster.randomHost() + urlSuffix;
  58.     }
  59. }


最後就是怎麼呼叫了，這裡使用的是HttpClientPool來呼叫http連線，關於HttpClientPool詳見我的另一篇文章：http://blog.itpub.net/28912557/viewspace-1223241/

點選(此處)摺疊或開啟

  1. public class HttpClientPool extends GenericObjectPool<HttpClient> {

  3.     private int httpsPort;

  5.     public HttpClientPool(PoolableObjectFactory<HttpClient> factory) {
  6.         super(factory);
  7.     }

  9.     public <T> T doPost(ClusterRetryHttpMethod method, HttpClientDataCallback<T> callback) {
  10.         HttpClient toUse = null;
  11.         HttpMethod m = null;
  12.         int index = 0;
  13.         if (method == null) {
  14.             return null;
  15.         }
  16.         if (method.isHttps()) {
  17.             Protocol myhttps = new Protocol(\"https\", new SSLProtocolSocketFactoryImpl(), httpsPort);
  18.             Protocol.registerProtocol(\"https\", myhttps);
  19.         }
  20.         try {
  21.             toUse = borrowObject();
  22.             while (index <= method.getRetry()) {
  23.                 try {
  24.                     m = method.randomMethod();
  25.                     toUse.executeMethod(m);
  26.                     T rel = callback.handleResponse(m.getResponseBodyAsString());
  27.                     return rel;
  28.                 } catch (Exception e) {
  29.                     logger.error(\"failed to execute http request.\", e);
  30.                     index++;
  31.                 } finally {
  32.                     try {
  33.                         m.releaseConnection();
  34.                     } catch (Exception e) {
  35.                         // in case fail, ignore and return object
  36.                     }
  37.                 }
  38.             }
  39.         } catch (Exception e) {
  40.             return null;
  41.         } finally {
  42.             if (toUse != null) {
  43.                 try {
  44.                     returnObject(toUse);
  45.                 } catch (Exception e) {
  46.                 }
  47.             }
  48.             if (method.isHttps()) {
  49.                 try {
  50.                     Protocol.unregisterProtocol(\"https\");
  51.                 } catch (Exception e) {
  52.                 }
  53.             }
  54.         }
  55.         // all retry failed
  56.         return null;

  58.     }


  61.     public int getHttpsPort() {
  62.         return httpsPort;
  63.     }

  65.     public void setHttpsPort(int httpsPort) {
  66.         this.httpsPort = httpsPort;
  67.     }
  68. }


來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/28912557/viewspace-1356116/，如需轉載，請註明出處，否則將追究法律責任。

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