发送请求

  • getForObject()：返回的是指定的类型
  • getForEntity()：返回ResponseEntity

  • exchange()：RequestEntity参数可设置Header，返回ResponseEntity

    构造uri

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    指定请求头

    image.png
    常用头：
    image.png
    自定义头：
    image.png

  • 构造请求体RequestEntity

  • 调用template.exchange()

    类型转换

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    泛型List

  • 泛型list：ParameterizedTypeReference

    • 因为泛型擦除

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@JsonComponent 自定义Serializer、Deserializer

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RestTemplate支持HTTP库

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连接管理

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  • 默认keepalive：如果没有keep-alive参数，则连接永久有效【坑】。

    Spring中配置RestTemplate

    1. /**
    2. * KeepAlive策略
    3. */
    4. public class CustomConnectionKeepAliveStrategy implements ConnectionKeepAliveStrategy {
    5.   private final long DEFAULT_SECONDS = 30;
    7.   @Override
    8.   public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
    9.       return Arrays.asList(response.getHeaders(HTTP.CONN_KEEP_ALIVE))
    10.               .stream()
    11.               .filter(h -> StringUtils.equalsIgnoreCase(h.getName(), "timeout")
    12.                       && StringUtils.isNumeric(h.getValue()))
    13.               .findFirst()
    14.               .map(h -> NumberUtils.toLong(h.getValue(), DEFAULT_SECONDS))
    15.               .orElse(DEFAULT_SECONDS) * 1000;
    16.   }
    17. }
    1.  @Bean
    2.  public HttpComponentsClientHttpRequestFactory requestFactory() {
    3.     PoolingHttpClientConnectionManager connectionManager =
    4.           new PoolingHttpClientConnectionManager(30, TimeUnit.SECONDS);
    5.     connectionManager.setMaxTotal(200);
    6.     connectionManager.setDefaultMaxPerRoute(20);
    8.     CloseableHttpClient httpClient = HttpClients.custom()
    9.           .setConnectionManager(connectionManager)
    10.           .evictIdleConnections(30, TimeUnit.SECONDS)
    11.           .disableAutomaticRetries()//禁用自动重试
    12.           // 有 Keep-Alive 认里面的值，没有的话永久有效
    13.           //.setKeepAliveStrategy(DefaultConnectionKeepAliveStrategy.INSTANCE)
    14.           // 换成自定义的keepalive策略
    15.           .setKeepAliveStrategy(new CustomConnectionKeepAliveStrategy())
    16.           .build();
    18.     HttpComponentsClientHttpRequestFactory requestFactory =
    19.           new HttpComponentsClientHttpRequestFactory(httpClient);
    21.     return requestFactory;
    22.  }
    24.  @Bean
    25.  public RestTemplate restTemplate(RestTemplateBuilder builder) {
    26. //    return new RestTemplate();
    28.     return builder
    29.           .setConnectTimeout(Duration.ofMillis(100))
    30.           .setReadTimeout(Duration.ofMillis(500))
    31.           .requestFactory(this::requestFactory)
    32.           .build();
    33.  }

    RestTemplate错误处理

    RestTemplate的错误处理_achang07的博客-CSDN博客