一：HttpClient简介

1.：由 apache 推出的实现使用 java 代码完成请求/响应的一套 API

2：实现效果：模拟浏览器发送请求及解析响应内容

3.：常用类

CloseableHttpClient ：负责发送请求和接收响应.相当于浏览器 HttpPost：Post请求对象，所有请求信息都放入到这个对象中 HttpGet：get请求对象，所有请求信息都放入到这个对象中 CloseableHttpResponse：响应对象,所有响应信息放入到这个类 EntityUtils：工具类，解析响应体

二：测试代码

1：maven依赖

<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.4.1</version> </dependency>

2：get请求

2.1：不带参数

public void doGet() throws Exception { //创建一个httpclient对象 CloseableHttpClient httpClient = HttpClients.createDefault(); //创建一个GET对象 HttpGet get = new HttpGet("http://www.sogou.com"); //执行请求 CloseableHttpResponse response = httpClient.execute(get); //取响应的结果 int statusCode = response.getStatusLine().getStatusCode(); System.out.println(statusCode); HttpEntity entity = response.getEntity(); String string = EntityUtils.toString(entity, "utf-8"); System.out.println(string); //关闭httpclient response.close(); httpClient.close(); }

2.2：带参数

public void doGetWithParam() throws Exception{ //创建一个httpclient对象 CloseableHttpClient httpClient = HttpClients.createDefault(); //创建一个uri对象 URIBuilder uriBuilder = new URIBuilder("http://www.sogou.com/web"); uriBuilder.addParameter("query", "花千骨"); HttpGet get = new HttpGet(uriBuilder.build()); //执行请求 CloseableHttpResponse response = httpClient.execute(get); //取响应的结果 int statusCode = response.getStatusLine().getStatusCode(); System.out.println(statusCode); HttpEntity entity = response.getEntity(); String string = EntityUtils.toString(entity, "utf-8"); System.out.println(string); //关闭httpclient response.close(); httpClient.close(); }

3：post请求

3.1：不带参数

public void doPost() throws Exception { CloseableHttpClient httpClient = HttpClients.createDefault(); //创建一个post对象 HttpPost post = new HttpPost("http://localhost:8082/httpclient/post.html"); //执行post请求 CloseableHttpResponse response = httpClient.execute(post); String string = EntityUtils.toString(response.getEntity()); System.out.println(string); response.close(); httpClient.close(); }

3.2：带参数

public void doPostWithParam() throws Exception{ CloseableHttpClient httpClient = HttpClients.createDefault(); //创建一个post对象 HttpPost post = new HttpPost("http://localhost:8082/httpclient/post.html"); //创建一个Entity。模拟一个表单 List<NameValuePair> kvList = new ArrayList<>(); kvList.add(new BasicNameValuePair("username", "zhangsan")); kvList.add(new BasicNameValuePair("password", "123")); //包装成一个Entity对象 StringEntity entity = new UrlEncodedFormEntity(kvList, "utf-8"); //设置请求的内容 post.setEntity(entity); //执行post请求 CloseableHttpResponse response = httpClient.execute(post); String string = EntityUtils.toString(response.getEntity()); System.out.println(string); response.close(); httpClient.close(); }