摘要：設(shè)置在多次嘗試同一請(qǐng)求時(shí)應(yīng)該遵守的超時(shí)，默認(rèn)值為秒，與默認(rèn)超時(shí)相同。如果自定義超時(shí)，則應(yīng)相應(yīng)地調(diào)整最大重試超時(shí)。設(shè)置一個(gè)監(jiān)聽(tīng)器，每次節(jié)點(diǎn)出現(xiàn)故障時(shí)都會(huì)收到通知，以防需要采取措施，當(dāng)啟用故障嗅探時(shí)在內(nèi)部使用。

可以通過(guò)相應(yīng)的RestClientBuilder類構(gòu)建RestClient實(shí)例，通過(guò)RestClient#builder(HttpHost...)靜態(tài)方法創(chuàng)建，唯一必需的參數(shù)是客戶端將與之通信的一個(gè)或多個(gè)主機(jī)，作為HttpHost的實(shí)例提供，如下所示：

RestClient restClient = RestClient.builder(
        new HttpHost("localhost", 9200, "http"),
        new HttpHost("localhost", 9201, "http")).build();

RestClient類是線程安全的，理想情況下與使用它的應(yīng)用程序具有相同的生命周期，重要的是不再需要時(shí)關(guān)閉它，以便它所使用的所有資源得到正確釋放，以及底層的http客戶端實(shí)例及其線程：

restClient.close();

RestClientBuilder還允許在構(gòu)建RestClient實(shí)例時(shí)可選地設(shè)置以下配置參數(shù)：

RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
Header[] defaultHeaders = new Header[]{new BasicHeader("header", "value")};
builder.setDefaultHeaders(defaultHeaders);

設(shè)置需要隨每個(gè)請(qǐng)求一起發(fā)送的默認(rèn)headers，以防止必須為每個(gè)請(qǐng)求指定它們。

RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
builder.setMaxRetryTimeoutMillis(10000);

設(shè)置在多次嘗試同一請(qǐng)求時(shí)應(yīng)該遵守的超時(shí)，默認(rèn)值為30秒，與默認(rèn)socket超時(shí)相同。如果自定義socket超時(shí)，則應(yīng)相應(yīng)地調(diào)整最大重試超時(shí)。

RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
builder.setFailureListener(new RestClient.FailureListener() {
    @Override
    public void onFailure(Node node) {
        
    }
});

設(shè)置一個(gè)監(jiān)聽(tīng)器，每次節(jié)點(diǎn)出現(xiàn)故障時(shí)都會(huì)收到通知，以防需要采取措施，當(dāng)啟用故障嗅探時(shí)在內(nèi)部使用。

RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
builder.setNodeSelector(NodeSelector.SKIP_DEDICATED_MASTERS);

設(shè)置用于過(guò)濾節(jié)點(diǎn)的節(jié)點(diǎn)選擇器，客戶端將發(fā)送請(qǐng)求到設(shè)置給客戶端本身的節(jié)點(diǎn)之一，這有助于防止在啟用嗅探時(shí)向?qū)Ｓ弥鞴?jié)點(diǎn)發(fā)送請(qǐng)求，默認(rèn)情況下，客戶端向每個(gè)配置的節(jié)點(diǎn)發(fā)送請(qǐng)求。

RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
builder.setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
    @Override
    public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder requestConfigBuilder) {
        return requestConfigBuilder.setSocketTimeout(10000); 
    }
});

設(shè)置允許修改默認(rèn)請(qǐng)求配置的回調(diào)（例如請(qǐng)求超時(shí)，身份驗(yàn)證或org.apache.http.client.config.RequestConfig.Builder允許設(shè)置的任何內(nèi)容）。

RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
builder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
    @Override
    public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
        return httpClientBuilder.setProxy(new HttpHost("proxy", 9000, "http"));  
    }
});

設(shè)置允許修改http客戶端配置的回調(diào)（例如通過(guò)ssl進(jìn)行加密通信，或者org.apache.http.impl.nio.client.HttpAsyncClientBuilder允許設(shè)置的任何內(nèi)容）。