介绍
HttpClient 是Apache Jakarta Common 下的子项目，可以用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。
maven坐标
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.13</version>
</dependency>
核心API：
HttpClient
HttpClients
CloseableHttpClient
HttpGet
HttpPost
发送请求步骤：
创建HttpClient对象
创建Http请求对象
调用HttpClient的execute方法发送请求
在idea中操作
测试HttpClient发送Get请求，在测试类中进行测试，前提是项目要运行起来。
测试的接口必须是get请求的
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
public class HttpClientTest {
/**
* 测试HttpClient发送Get请求
*/
@Test
public void testGet() throws Exception{
//创建HttpClient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建Http请求对象
HttpGet httpGet = new HttpGet("http://localhost:8080/user/shop/status");
//调用HttpClient对象的execute方法发送请求
CloseableHttpResponse response = httpClient.execute(httpGet);
//获取服务端响应的状态码
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("服务端返回的状态码:"+statusCode);
HttpEntity entity = response.getEntity();
String body = EntityUtils.toString(entity);
System.out.println("服务端返回的内容:"+body);
//关闭资源
response.close();
httpClient.close();
}
测试结果：
测试HttpClient发送Post请求，在测试类中进行测试，前提是项目要运行起来。
测试的接口必须是Post请求的
/**
* 测试HttpClient发送Post请求
*/
@Test
public void testPost() throws Exception{
//创建HttpClient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建Http请求对象
HttpPost httpPost= new HttpPost("http://localhost:8080/admin/employee/login");
JSONObject jsonObject=new JSONObject();
jsonObject.put("username","admin");
jsonObject.put("password","123456");
StringEntity entity=new StringEntity(jsonObject.toString());
entity.setContentEncoding("UTF-8");
entity.setContentType("application/json");
//调用HttpClient对象的execute方法发送请求
CloseableHttpResponse response = httpClient.execute(httpPost);
//获取服务端响应的状态码
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("服务端返回的状态码:"+statusCode);
HttpEntity httpEntity = response.getEntity();
String body = EntityUtils.toString(httpEntity);
System.out.println("服务端返回的内容:"+body);
//关闭资源
response.close();
httpClient.close();
}测试结果：
一般在项目中如果要发送HTTP请求我们可以创建一个工具类来使用以下是我编写的工具类
/**
* Http工具类
*/
public class HttpClientUtil {
static final int TIMEOUT_MSEC = 5 * 1000;
/**
* 发送GET方式请求
*
* @param url
* @param paramMap
* @return
*/
public static String doGet(String url, Map<String, String> paramMap) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
String result = "";
CloseableHttpResponse response = null;
try {
URIBuilder builder = new URIBuilder(url);
if (paramMap != null) {
for (String key : paramMap.keySet()) {
builder.addParameter(key, paramMap.get(key));
}
}
URI uri = builder.build();
//创建GET请求
HttpGet httpGet = new HttpGet(uri);
//发送请求
response = httpClient.execute(httpGet);
//判断响应状态
if (response.getStatusLine().getStatusCode() == 200) {
result = EntityUtils.toString(response.getEntity(), "UTF-8");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return result;
}
/**
* 发送POST方式请求
*
* @param url
* @param paramMap
* @return
* @throws IOException
*/
public static String doPost(String url, Map<String, String> paramMap) throws IOException {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (paramMap != null) {
List<NameValuePair> paramList = new ArrayList();
for (Map.Entry<String, String> param : paramMap.entrySet()) {
paramList.add(new BasicNameValuePair(param.getKey(), param.getValue()));
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
httpPost.setEntity(entity);
}
httpPost.setConfig(builderRequestConfig());
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
} catch (Exception e) {
throw e;
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
/**
* 发送POST方式请求
*
* @param url
* @param paramMap
* @return
* @throws IOException
*/
public static String doPost4Json(String url, Map<String, String> paramMap) throws IOException {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
if (paramMap != null) {
//构造json格式数据
JSONObject jsonObject = new JSONObject();
for (Map.Entry<String, String> param : paramMap.entrySet()) {
jsonObject.put(param.getKey(), param.getValue());
}
StringEntity entity = new StringEntity(jsonObject.toString(), "utf-8");
//设置请求编码
entity.setContentEncoding("utf-8");
//设置数据类型
entity.setContentType("application/json");
httpPost.setEntity(entity);
}
httpPost.setConfig(builderRequestConfig());
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
} catch (Exception e) {
throw e;
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
private static RequestConfig builderRequestConfig() {
return RequestConfig.custom()
.setConnectTimeout(TIMEOUT_MSEC)
.setConnectionRequestTimeout(TIMEOUT_MSEC)
.setSocketTimeout(TIMEOUT_MSEC).build();
}
}