RestTemplate使用詳解

1.RestTemplate添加RequestHeader如content-type可通過httpclient設置

        List<Header> headers = new ArrayList<>();
        headers.add(new BasicHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.16 Safari/537.36"));
        headers.add(new BasicHeader("Accept-Encoding", "gzip,deflate"));
        headers.add(new BasicHeader("Accept-Language", "zh-CN"));
        headers.add(new BasicHeader("Connection", "Keep-Alive"));
 
        httpClientBuilder.setDefaultHeaders(headers);
 
        HttpClient httpClient = httpClientBuilder.build();
 
        // httpClient連接配置，底層是配置RequestConfig
        HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(httpClient);

        restTemplate.setRequestFactory(clientHttpRequestFactory);

2.使用中進行異常處理

try catch

 

    public String postRemoteData(ParameterRo ro) throws UnsupportedEncodingException {
        /**
         * 設置請求頭
         */
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/json;charset=UTF-8"));
        headers.add("Accept", MediaType.APPLICATION_JSON.toString());

        /**
         * POST請求參數，根據需要進行封裝
         */
        String bodyData = new String(Base64Util.encodeData(JSON.toJSONString(ro)).getBytes("UTF-8"), "UTF-8");

        /**
         * 查看HttpEntity的構造方法，包含只有請求頭和只有請求體的情況
         */
        HttpEntity<String> httpEntity = new HttpEntity<String>(bodyData, headers);

        /**
         * 執行操作
         */
        String result = restTemplate.postForObject(remoteUrl, httpEntity, String.class);

        return result;
    }

3.控制超時，使用連接池，編碼轉換

RestTemplate是Spring提供的用於訪問Rest服務的客戶端，RestTemplate提供了多種便捷訪問遠程Http服務的方法，能夠大大提高客戶端的編寫效率。
調用RestTemplate的默認構造函數，RestTemplate對象在底層通過使用java.net包下的實現創建HTTP 請求，可以通過使用ClientHttpRequestFactory指定不同的HTTP請求方式。
ClientHttpRequestFactory接口主要提供了兩種實現方式

• 一種是SimpleClientHttpRequestFactory，使用J2SE提供的方式（既java.net包提供的方式）創建底層的Http請求連接。
• 一種方式是使用HttpComponentsClientHttpRequestFactory方式，底層使用HttpClient訪問遠程的Http服務，使用HttpClient可以配置連接池和證書等信息。

 　　RestTemplate默認是使用SimpleClientHttpRequestFactory，內部是調用jdk的HttpConnection，默認超時為-1

   public RestTemplate(ClientHttpRequestFactory requestFactory) {
    this();
    setRequestFactory(requestFactory);
   }

     其中，第二個構造方法中可以傳入ClientHttpRequestFactory參數，第一個進行默認初始化，因為我們經常需要對請求超時進行設置並能 夠對超時進行后續處理，而第      一個構造方法，我們無法控制超時時間，第二個構造中的ClientHttpRequestFactory接口的實現類中存在 timeout屬性，因此選用第二個構造方法

 

//創建HTTP客戶端工廠 private ClientHttpRequestFactory createFactory() { if (this.maxTotalConnect <= 0) { SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory(); factory.setConnectTimeout(this.connectTimeout); factory.setReadTimeout(this.readTimeout); return factory; } HttpClient httpClient = HttpClientBuilder.create().setMaxConnTotal(this.maxTotalConnect) .setMaxConnPerRoute(this.maxConnectPerRoute).build(); HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory( httpClient); factory.setConnectTimeout(this.connectTimeout); factory.setReadTimeout(this.readTimeout); return factory; } //初始化RestTemplate,並加入spring的Bean工廠，由spring統一管理 @Bean @ConditionalOnMissingBean(RestTemplate.class) public RestTemplate getRestTemplate() { RestTemplate restTemplate = new RestTemplate(this.createFactory()); List<HttpMessageConverter<?>> converterList = restTemplate.getMessageConverters(); //重新設置StringHttpMessageConverter字符集為UTF-8，解決中文亂碼問題 HttpMessageConverter<?> converterTarget = null; for (HttpMessageConverter<?> item : converterList) { if (StringHttpMessageConverter.class == item.getClass()) { converterTarget = item; break; } } if (null != converterTarget) { converterList.remove(converterTarget); } converterList.add(1, new StringHttpMessageConverter(StandardCharsets.UTF_8)); //加入FastJson轉換器 converterList.add(new FastJsonHttpMessageConverter4()); return restTemplate; }

 

@Bean public HttpMessageConverters fastjsonConverter() { FastJsonConfig fastJsonConfig = new FastJsonConfig(); //自定義格式化輸出 fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat, SerializerFeature.WriteNullStringAsEmpty, SerializerFeature.WriteNullNumberAsZero); FastJsonHttpMessageConverter4 fastjson = new FastJsonHttpMessageConverter4(); fastjson.setFastJsonConfig(fastJsonConfig); return new HttpMessageConverters(fastjson); }

 

 

@Component
@Lazy(false)
public class RestClient {
 
    private static final Logger LOGGER = LoggerFactory.getLogger(SimpleRestClient.class);
 
    private static RestTemplate restTemplate;
 
    static {
        // 長連接保持30秒
        PoolingHttpClientConnectionManager pollingConnectionManager = new PoolingHttpClientConnectionManager(30, TimeUnit.SECONDS);
        // 總連接數
        pollingConnectionManager.setMaxTotal(1000);
        // 同路由的並發數
        pollingConnectionManager.setDefaultMaxPerRoute(1000);
 
        HttpClientBuilder httpClientBuilder = HttpClients.custom();
        httpClientBuilder.setConnectionManager(pollingConnectionManager);
        // 重試次數，默認是3次，沒有開啟
        httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(2, true));
        // 保持長連接配置，需要在頭添加Keep-Alive
        httpClientBuilder.setKeepAliveStrategy(new DefaultConnectionKeepAliveStrategy());
 
//        RequestConfig.Builder builder = RequestConfig.custom();
//        builder.setConnectionRequestTimeout(200);
//        builder.setConnectTimeout(5000);
//        builder.setSocketTimeout(5000);
//
//        RequestConfig requestConfig = builder.build();
//        httpClientBuilder.setDefaultRequestConfig(requestConfig);
 
        List<Header> headers = new ArrayList<>();
        headers.add(new BasicHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.16 Safari/537.36"));
        headers.add(new BasicHeader("Accept-Encoding", "gzip,deflate"));
        headers.add(new BasicHeader("Accept-Language", "zh-CN"));
        headers.add(new BasicHeader("Connection", "Keep-Alive"));
 
        httpClientBuilder.setDefaultHeaders(headers);
 
        HttpClient httpClient = httpClientBuilder.build();
 
        // httpClient連接配置，底層是配置RequestConfig
        HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(httpClient);
        // 連接超時
        clientHttpRequestFactory.setConnectTimeout(5000);
        // 數據讀取超時時間，即SocketTimeout
        clientHttpRequestFactory.setReadTimeout(5000);
        // 連接不夠用的等待時間，不宜過長，必須設置，比如連接不夠用時，時間過長將是災難性的
        clientHttpRequestFactory.setConnectionRequestTimeout(200);
        // 緩沖請求數據，默認值是true。通過POST或者PUT大量發送數據時，建議將此屬性更改為false，以免耗盡內存。
        // clientHttpRequestFactory.setBufferRequestBody(false);
 
        // 添加內容轉換器
        List<HttpMessageConverter<?>> messageConverters = new ArrayList<>();
        messageConverters.add(new StringHttpMessageConverter(Charset.forName("UTF-8")));
        messageConverters.add(new FormHttpMessageConverter());
        messageConverters.add(new MappingJackson2XmlHttpMessageConverter());
        messageConverters.add(new MappingJackson2HttpMessageConverter());
 
        restTemplate = new RestTemplate(messageConverters);
        restTemplate.setRequestFactory(clientHttpRequestFactory);
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
 
        LOGGER.info("RestClient初始化完成");
    }
 
    private RestClient() {
 
    }
 
    @PostConstruct
    public static RestTemplate getClient() {
        return restTemplate;
    }
 
}
參考網頁：http://blog.csdn.net/clj198606061111/article/details/70227571，http://blog.csdn.net/u010476464/article/details/50067079，http://www.cnblogs.com/winner-0715/p/6258139.html