版權聲明：本文為部落客chszs的原創文章，未經部落客允許不得轉載。 https://blog.csdn.net/chszs/article/details/16854747

《Apache HttpClient 4.3開發指南》

作者：chszs，轉載需注明。部落格首頁：

http://blog.csdn.net/chszs

一、概述

Apache HttpClient 4系列已經釋出很久了，但由于它與HttpClient 3.x版本完全不相容，以至于業内采用此庫的公司較少，在網際網路上也少有相關的文檔資料分享。

本文旨在寫一個簡要的Apache HttpClient 4.3開發指南，幫助開發者快速上手Apache HttpClient 4.3.x庫。

要注意的是，本文檔中的代碼在低于HttpClient 4.3版本的地方可能不能運作。

二、開發手冊

1、建立HTTP用戶端

CloseableHttpClient client = HttpClientBuilder.create().build();           

2、發送基本的GET請求

instance.execute(new HttpGet(“http://www.baidu.com”));           

3、擷取HTTP響應的狀态碼

String url = “http://www.baidu.com”;
CloseableHttpResponse response = instance.execute(new HttpGet(url));
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));           

4、擷取響應的媒體類型

String url = “http://www.baidu.com”;
CloseableHttpResponse response = instance.execute(new HttpGet(url));
String contentMimeType = ContentType.getOrDefault(response.getEntity()).getMimeType();
assertThat(contentMimeType, equalTo(ContentType.TEXT_HTML.getMimeType()));           

5、擷取響應的BODY部分

String url = “http://www.baidu.com”;
CloseableHttpResponse response = instance.execute(new HttpGet(url));
String bodyAsString = EntityUtils.toString(response.getEntity());
assertThat(bodyAsString, notNullValue());           

6、配置請求的逾時設定

@Test(expected=SocketTimeoutException.class)
public void givenLowTimeout_whenExecutingRequestWithTimeout_thenException() throws ClientProtocolException, IOException{
    RequestConfig requestConfig = RequestConfig.custom()
	.setConnectionRequestTimeout(50).setConnectTimeout(50)
	.setSocketTimeout(50).build();
    HttpGet request = new HttpGet(SAMPLE_URL);
    request.setConfig(requestConfig);
    instance.execute(request);
}
           

7、發送POST請求

instance.execute(new HttpPost(SAMPLE_URL));           

8、為HTTP請求配置重定向

CloseableHttpClient instance = HttpClientBuilder.create().disableRedirectHandling().build();
CloseableHttpResponse response = instance.execute(new HttpGet(SAMPLE_URL));
assertThat(reponse.getStatusLine().getStatusCode(), equalTo(301));           

9、配置請求的HEADER部分

HttpGet request = new HttpGet(SAMPLE_URL);
request.addHeader(HttpHeaders.ACCEPT, “application/xml”);
response = instance.execute(request);           

10、擷取響應的HEADER部分

CloseableHttpResponse response = instance.execute(new HttpGet(SAMPLE_URL));
Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
assertThat(headers, not(emptyArray()));           

11、關閉或釋放資源

response = instance.execute(new HttpGet(SAMPLE_URL));
try{
  HttpEntity entity = response.getEntity();
  if(entity!=null){
InputStream instream = entity.getContent();
instream.close();
  }
} finally{
  response.close();
}           

以上内容涵蓋了HttpClient 4.3所有常見的需求，供開發者參考。