一、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
1、作用
- 发送 HTTP 请求
- 接收响应数据
2、应用场景
当我们在使用扫描支付、查看地图、获取验证码、查看天气等功能时
其实，应用程序本身并未实现这些功能，都是在应用程序里访问提供这些功能的服务，访问这些服务需要发送 HTTP 请求，并且接收响应数据，可通过 HttpClient 来实现
3、核心 API
- HttpClient：Http 客户端对象类型，使用该类型对象可发起 Http 请求
- HttpClients：可认为是构建器，可创建 HttpClient 对象
- CloseableHttpClient：实现类，实现了 HttpClient 接口
- HttpGet：Get 方式请求类型
- HttpPost：Post 方式请求类型
4、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
二、编码使用
1、导入 Maven 坐标
xml
<dependency>
<groupId>com.aliyun.oss</groupId>
<artifactId>aliyun-sdk-oss</artifactId>
</dependency>2、发送 Get 请求
步骤：
- 创建HttpClient对象
- 创建请求对象
- 发送请求，接受响应结果
- 解析结果
- 关闭资源
编码：
java
@SpringBootTest
public class HttpClientTest {
/**
* 测试httpclient发送GET方式的请求
*/
@Test
public void testGET() throws Exception{
//1.创建httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
//2.创建请求对象
HttpGet httpGet = new HttpGet("http://localhost:8080/test");
//3.发送请求，接受响应结果
CloseableHttpResponse response = httpClient.execute(httpGet);
//4.解析结果
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("服务端返回的状态码为：" + statusCode);
HttpEntity entity = response.getEntity();
String body = EntityUtils.toString(entity);
System.out.println("服务端返回的数据为：" + body);
//5.关闭资源
response.close();
httpClient.close();
}
}3、发送 Post 请求
步骤：
- 创建HttpClient对象
- 创建请求对象
- 发送请求，接受响应结果
- 解析结果
- 关闭资源
编码：
java
@SpringBootTest
public class HttpClientTest {
/**
* 测试httpclient发送POST方式的请求
*/
@Test
public void testPOST() throws Exception{
//1.创建httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
//2.创建请求对象
HttpPost httpPost = new HttpPost("http://localhost:8080/test");
JSONObject jsonObject = new JSONObject();
jsonObject.put("username","admin");
jsonObject.put("password","123456");
StringEntity entity = new StringEntity(jsonObject.toString());
//指定请求编码方式
entity.setContentEncoding("utf-8");
//数据格式
entity.setContentType("application/json");
httpPost.setEntity(entity);
//3.发送请求
CloseableHttpResponse response = httpClient.execute(httpPost);
//4.解析返回结果
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("响应码为：" + statusCode);
HttpEntity entity1 = response.getEntity();
String body = EntityUtils.toString(entity1);
System.out.println("响应数据为：" + body);
//5.关闭资源
response.close();
httpClient.close();
}
}三、封装 HttpClientUtil 工具类
java
/**
* 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();
}
}