Java HTTP client常见库

前言

每种编程语言里最常用的库恐怕是Http请求库了，如python里的requests包，nodejs里的request模块。
在Java世界里，也是百花齐放，山头林立。常用的有：

HttpURLConnection: 最早的JDK提供的类
Java 11提供的HttpClient
Apache HttpComponents项目中的HTTPClient
Square提供的OkHttpClient
Spring 自带的WebClient

Apache HttpComponents

该组件提供了两个核心类：

HttpCore: 更底层的传输处理类
HttpClient：基于HttpCore实现的HTTP-compliant 处理类

JDK 11+ HTTP Client使用举例

Post同步的json数据：

public void invokePost() {
    
    
  
  try {
    
    
   String requestBody = prepareRequest();
   HttpClient client = HttpClient.newHttpClient();
   HttpRequest request = HttpRequest
     .newBuilder()
     .uri(URI.create("https://reqbin.com/echo/post/json"))
     .POST(HttpRequest.BodyPublishers.ofString(requestBody))
     .header("Accept", "application/json")
     .build();

   HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());

   System.out.println(response.body());
  } catch (IOException | InterruptedException e) {
    
    
   e.printStackTrace();
  }
 }

 private String prepareRequest() throws JsonProcessingException {
    
    
  var values = new HashMap<String, String>() {
    
    
   {
    
    
    put("Id", "12345");
    put("Customer", "Roger Moose");
    put("Quantity", "3");
    put("Price","167.35");
   }
  };

  var objectMapper = new ObjectMapper();
  String requestBody = objectMapper.writeValueAsString(values);
  return requestBody;
 }

发送异步请求：

public void invoke() throws URISyntaxException {
    
    
  
  HttpClient client = HttpClient.newBuilder()
      .version(Version.HTTP_2)
      .followRedirects(Redirect.NORMAL)
      .build();
  
  HttpRequest request = HttpRequest.newBuilder()
     .uri(new URI(URLConstants.URL))
     .GET()
     .header(URLConstants.API_KEY_NAME, URLConstants.API_KEY_VALUE)
     .timeout(Duration.ofSeconds(10))
     .build();
  
  
  client.sendAsync(request, BodyHandlers.ofString())
    .thenApply(HttpResponse::body)
    .thenAccept(System.out::println)
    .join();
 }

HTTP Client包装库

cVurl

cVurl is an open-source wrapper for the Java HTTP client. It is written in Java 11 and can be used with any JDK 11.0.2 or newer.

public void cVurl() {
    
    
    CVurl cVurl = new CVurl();

    //POST
    Result result = cVurl.post("https://api.imgflip.com/caption_image")
        .queryParams(Map.of(
                "template_id", "112126428",
        "username", "test-user",
        "password", "123test321",
        "text0", "text0",
        "text1", "text1"
        ))
        .asObject(Result.class);

    System.out.println("CVurl POST: " + result);
}

它支持Compression、Multipart、Form data这些Java 11 HttpClient不具备的特性。

Avaje-HTTP

Fluid API for building URLs and payload
JSON marshaling using Avaje Jsonb/Jackson/Gson
Light Feign-style interfaces via annotation processing.
Request/Response Interception
Authorization via Basic Auth or OAuth Bearer Tokens
Async and sync API

个人建议

在实际项目中，设计符合自身项目需求的HTTP client接口，并基于JDK 11 HTTP client实现，独立于任何上述库。

参考链接

https://github.com/corese4rch/cvurl
https://github.com/avaje/avaje-http/tree/master
https://reflectoring.io/comparison-of-java-http-clients/