主要参考了 Baeldung 的 HttpClient 4 Cookbook

创建 HttpClient

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

发送 GET 请求

HttpGet httpGet = new HttpGet("http://www.baidu.com");
CloseableHttpResponse response = httpClient.execute(httpGet);

获取 HTTP Response 的状态码

CloseableHttpResponse response = httpClient.execute(httpGet);
Assert.assertEquals(HttpStatus.SC_OK, response.getStatusLine().getStatusCode());

获取 HTTP Response 的 Media Type

CloseableHttpResponse response = httpClient.execute(httpGet);
String contentMimeType = ContentType.getOrDefault(response.getEntity()).getMimeType();
Assert.assertEquals(ContentType.TEXT_HTML.getMimeType(), contentMimeType);

获取 HTTP Response 的内容

CloseableHttpResponse response = httpClient.execute(httpGet);
String bodyAsString = EntityUtils.toString(response.getEntity());
Assert.assertNotNull(bodyAsString);

获取 HTTP Response 响应头部信息

CloseableHttpClient httpClient = HttpClientBuilder.create().build();
HttpGet httpGet = new HttpGet("http://localhost:8080/hello");
CloseableHttpResponse response = httpClient.execute(httpGet);
Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
Assert.assertNotSame(0,headers.length);

设置请求的超时时间

HttpGet httpGet = new HttpGet("http://www.baidu.com");
RequestConfig requestConfig = RequestConfig.custom()
        .setConnectionRequestTimeout(1000)
        .setConnectTimeout(1000)
        .setSocketTimeout(1000).build();
httpGet.setConfig(requestConfig);
CloseableHttpResponse response = httpClient.execute(httpGet);

设置 HttpClient 的超时时间

RequestConfig requestConfig = RequestConfig.custom()
                .setConnectionRequestTimeout(1000)
                .setConnectTimeout(1000)
                .setSocketTimeout(1000).build();
CloseableHttpClient httpClient = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).build();
HttpGet httpGet = new HttpGet("http://www.baidu.com");
CloseableHttpResponse response = httpClient.execute(httpGet);

设置请求头

CloseableHttpClient httpClient = HttpClientBuilder.create().build();
HttpGet httpGet = new HttpGet("http://www.baidu.com");
httpGet.addHeader(HttpHeaders.ACCEPT,"application/xml");
CloseableHttpResponse response = httpClient.execute(httpGet);

发送 POST 请求

CloseableHttpClient httpClient = HttpClientBuilder.create().build();
HttpPost httpPost = new HttpPost("http://www.baidu.com");
CloseableHttpResponse response = httpClient.execute(httpPost);

模拟表单提交的POST请求

CloseableHttpClient httpClient = HttpClientBuilder.create().build();
List<NameValuePair> parameters = new ArrayList<>();
parameters.add(new BasicNameValuePair("key1","value1"));
parameters.add(new BasicNameValuePair("key2","value2"));
HttpPost httpPost = new HttpPost("http://www.baidu.com");
httpPost.setEntity(new UrlEncodedFormEntity(parameters,Consts.UTF_8));
CloseableHttpResponse response = httpClient.execute(httpPost);

处理HTTP 重定向

HttpClient 默认策略会处理重定向请求，使用 disableRedirectHandling() 可以禁用重定向处理策略；

CloseableHttpClient instance = HttpClientBuilder.create().disableRedirectHandling().build();
CloseableHttpResponse response = instance.execute(new HttpGet("https://dwz.cn/IKeCGtaO"));
Assert.assertEquals(HttpStatus.SC_MOVED_TEMPORARILY,response.getStatusLine().getStatusCode());

关闭/释放资源

CloseableHttpClient httpClient = null;
CloseableHttpResponse response = null;
try {
    httpClient = HttpClientBuilder.create().build();
    HttpGet httpGet = new HttpGet("http://www.baidu.com");
    response = httpClient.execute(httpGet);
    Assert.assertEquals(HttpStatus.SC_OK, response.getStatusLine().getStatusCode());
    HttpEntity httpEntity = response.getEntity();
    if (null != httpEntity) {
        InputStream inputStream = httpEntity.getContent();
        inputStream.close();
    }
} catch (IOException e) {

} finally {
    response.close();
    HttpClientUtils.closeQuietly(httpClient);
}

项目代码

码云链接：httpClient 代码示例