1 概述
（1）HTTPClient 实现了所有 HTTP 的方法（包括 GET、POST、PUT、DELETE、OPTIONS
等），使用该工具包可以很方便的发起http请求。
（2）Maven 依赖
bash
<dependency>
<groupId>org.apache.httpcomponents.client5</groupId>
<artifactId>httpclient5</artifactId>
<version>5.3</version>
</dependency>（3）执行http请求的步骤如下：
- 创建 HttpClient 实例
- 创建请求实例（如 HttpGet）
- 执行请求
- 处理响应结果
- 关闭连接（释放资源）
2 Http接口案例
下面是几个 Http 接口。后续接口调用案例将调用下述接口。
java
@RestController
@RequestMapping("/request")
public class RequestTestController {
@GetMapping("/getWithoutParam")
public String getWithoutParam() {
return "data_getWithoutParam";
}
@GetMapping("/getWithParam")
public String getWithParam(String param, String param2) {
return "data_getWithParam_" + param + "_" + param2;
}
@PostMapping("/postWithoutParam")
public String postWithoutParam() {
return "data_postWithoutParam";
}
@PostMapping("/postWithParam")
public String postWithParam(@RequestBody PostWithParamDto param) {
return "data_postWithParam_" + param.getParam() + "_" + param.getParam2();
}
@Data
public static class PostWithParamDto {
private String param;
private String param2;
}
}3 get请求
下面是 get 请求的调用方式，分别为调用无入参和有入参的 get 接口。
3.1 get 无参
java
/**
* get 无参
*/
public void getWithoutParam() {
CloseableHttpResponse response = null;
// 创建 httpClient 实例
CloseableHttpClient httpClient = HttpClients.createDefault();
// 创建请求实例
HttpGet httpGet = new HttpGet("http://127.0.0.1:8080/request/getWithoutParam");
try {
// 执行请求
response = httpClient.execute(httpGet);
// 处理响应结果
if (response.getStatusLine().getStatusCode() != 200) {
log.error("http getWithoutParam error. response:{}", JSON.toJSONString(response));
return;
}
String resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
log.info("http getWithoutParam result:{}", JSON.toJSONString(resultString));
} catch (Exception e) {
log.error("http getWithoutParam error", e);
} finally {
// 关闭连接
try {
if (response != null) {
response.close();
}
httpClient.close();
} catch (Exception e) {
log.error("http getWithoutParam error", e);
}
}
}3.2 get 有参
java
public void getWithParam() {
CloseableHttpResponse response = null;
// 创建 httpClient 实例
CloseableHttpClient httpClient = HttpClients.createDefault();
// 创建请求实例
StringBuilder stringBuilder = new StringBuilder();
try {
stringBuilder.append("param=").append(URLEncoder.encode("123", "utf-8"));
stringBuilder.append("&");
stringBuilder.append("param2=").append(URLEncoder.encode("456", "utf-8"));
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
}
HttpGet httpGet = new HttpGet("http://127.0.0.1:8080/request/getWithParam?"+stringBuilder);
try {
// 执行请求
response = httpClient.execute(httpGet);
// 处理响应结果
if (response.getStatusLine().getStatusCode() != 200) {
log.error("http getWithParam error. response:{}", JSON.toJSONString(response));
return;
}
String resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
log.info("http getWithParam result:{}", JSON.toJSONString(resultString));
} catch (Exception e) {
log.error("http getWithParam error", e);
} finally {
// 关闭连接
try {
if (response != null) {
response.close();
}
httpClient.close();
} catch (Exception e) {
log.error("http getWithParam error", e);
}
}
}4 post 请求
下面是 post 请求的调用方式，分别为调用无入参和有入参的 post 接口。
4.1 post 无参
java
public void postWithoutParam() {
CloseableHttpResponse response = null;
// 创建 httpClient 实例
CloseableHttpClient httpClient = HttpClients.createDefault();
// 创建请求实例
HttpPost httpPost = new HttpPost("http://127.0.0.1:8080/request/postWithoutParam");
try {
// 执行请求
response = httpClient.execute(httpPost);
// 处理响应结果
if (response.getStatusLine().getStatusCode() != 200) {
log.error("http postWithoutParam error. response:{}", JSON.toJSONString(response));
return;
}
String resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
log.info("http postWithoutParam result:{}", JSON.toJSONString(resultString));
} catch (Exception e) {
log.error("http postWithoutParam error", e);
} finally {
// 关闭连接
try {
if (response != null) {
response.close();
}
httpClient.close();
} catch (Exception e) {
log.error("http postWithoutParam error", e);
}
}
}4.2 post 有参
java
public void postWithParam() {
CloseableHttpResponse response = null;
// 创建 httpClient 实例
CloseableHttpClient httpClient = HttpClients.createDefault();
// 创建请求实例
HttpPost httpPost = new HttpPost("http://127.0.0.1:8080/request/postWithParam");
// 接口请求参数 PostWithParamDto
PostWithParamDto postWithParamDto = new PostWithParamDto();
postWithParamDto.setParam("123");
postWithParamDto.setParam2("456");
StringEntity entity = new StringEntity(JSON.toJSONString(postWithParamDto), "UTF-8");
httpPost.setEntity(entity);
httpPost.setHeader("Content-Type", "application/json;charset=utf8");
try {
// 执行请求
response = httpClient.execute(httpPost);
// 处理响应结果
if (response.getStatusLine().getStatusCode() != 200) {
log.error("http postWithParam error. response:{}", JSON.toJSONString(response));
return;
}
String resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
log.info("http postWithParam result:{}", JSON.toJSONString(resultString));
} catch (Exception e) {
log.error("http postWithParam error", e);
} finally {
// 关闭连接
try {
if (response != null) {
response.close();
}
httpClient.close();
} catch (Exception e) {
log.error("http postWithParam error", e);
}
}
}
@Data
public static class PostWithParamDto {
private String param;
private String param2;
}