在Spring Boot下整合http client,方便客户端使用.

http client已经非常简单啦,为何还需要创建一个starter httpclient,其主要的目的如下:

• 让使用更简单,如全局proxy,timeout等
• 结合dropwizard metrics,添加对metrics的管理

• 在Spring Boot项目的pom.xml中添加以下依赖:

   <dependency>
   <groupId>org.mvnsearch.spring.boot</groupId>
   <artifactId>spring-boot-starter-httpclient</artifactId>
   <version>1.0.0-SNAPSHOT</version>
   </dependency>
  

• 在Spring Boot的application.properties文件中添加http client的一些相关配置,当然也可以不需要配置如下:

   spring.httpclient.connectTimeout=2000
  

• 接下来在你的代码中直接应用cacheManager,然后就可以啦。

   @Autowired
   private HttpClient httpClient;
   @Autowired
   private Executor executor;
  

• org.apache.http.client.HttpClient: Http Client
• org.apache.http.client.fluent.Executor: Executor

• http client:

   reporter.start(1, TimeUnit.SECONDS);
   HttpGet httpGet = new HttpGet("https://www.yahoo.com/tech/s/favorite-iphone-feature-apple-added-ios-9-2-183202009.html");
   HttpResponse response = httpClient.execute(httpGet);
   EntityUtils.toString(response.getEntity());
  

• executor:

   String content = executor.execute(Request.Get("https://www.yahoo.com/")).returnContent().asString();
  

HttpClient结合了DropWizard的metrics,这样很方便获取http client的metrics信息, 目前可以记录的级别主要是: METHOD_ONLY, HOST_AND_METHOD(default), QUERYLESS_URL_AND_METHOD, 以下是metrics的输出:

 -- Gauges ----------------------------------------------------------------------
 org.apache.http.conn.HttpClientConnectionManager.available-connections
 value = 1
 org.apache.http.conn.HttpClientConnectionManager.leased-connections
 value = 0
 org.apache.http.conn.HttpClientConnectionManager.max-connections
 value = 20
 org.apache.http.conn.HttpClientConnectionManager.pending-connections
 value = 0
 
 -- Timers ----------------------------------------------------------------------
 org.apache.http.client.HttpClient.www.yahoo.com.get-requests
 count = 1
 mean rate = 1.74 calls/second
 1-minute rate = 0.00 calls/second
 5-minute rate = 0.00 calls/second
 15-minute rate = 0.00 calls/second
 min = 117.63 milliseconds
 max = 117.63 milliseconds
 mean = 117.63 milliseconds
 stddev = 0.00 milliseconds
 median = 117.63 milliseconds
 75% <= 117.63 milliseconds
 95% <= 117.63 milliseconds
 98% <= 117.63 milliseconds
 99% <= 117.63 milliseconds
 99.9% <= 117.63 milliseconds

• HttpClient线程安全吗? HttpClient implementations are expected to be thread safe. It is recommended that the same instance of this class is reused for multiple request executions.

• 我用Commons HttpClient 3.x挺好的,为何换到http components上? Http Components是 commons-httpclient的替代者,建议使用http components

• Http Components: http://hc.apache.org/