import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
/*** @description 将RestTemplate注入到容器当中，让他保持单例，当我们哪个类要使用的时候直接从容器里面获取即可。这样可以避免每调用一次创建一个RestTemplate对象*/
@Configuration
public class ApplicationContextBean {@Beanpublic RestTemplate restTemplate() {return new RestTemplate();}
}

先注入单列模式

http发送get请求和POST2种请求方式

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson2.JSONObject;
import com.cdtye.common.core.utils.StringUtils;import lombok.extern.slf4j.Slf4j;
import okhttp3.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.*;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.io.File;
import java.io.IOException;
import java.util.Map;
import java.util.Objects;@Component
@Slf4j
public class HttpUtils {@Resourceprivate RestTemplate restTemplate;private static HttpUtils httpUtils;@PostConstructpublic void init(){httpUtils = this;httpUtils.restTemplate = this.restTemplate;}public static <T> String sendGetRequest(String url,String token, Map<String, Object> queryParams) {return getRequest(url, token,HttpMethod.GET, queryParams);}public static <T> String sendPostRequest(String url,String token, Map<String, Object> queryParams,Integer type) {return postRequest(url, token,queryParams,type);}public static <T> String getRequest(String url,String token, HttpMethod method, Map<String, Object> queryParams) {HttpHeaders headers = new HttpHeaders();//是否携带tokenif (StringUtils.isNotEmpty(token)){headers.add(HttpHeaders.AUTHORIZATION, "Bearer "+token);}if (queryParams != null && !queryParams.isEmpty()) {StringBuilder urlBuilder = new StringBuilder(url);urlBuilder.append("?");for (Map.Entry<String, Object> entry : queryParams.entrySet()) {urlBuilder.append(entry.getKey()).append("=").append(entry.getValue()).append("&");}url = urlBuilder.toString();}HttpEntity<String> requestEntity = new HttpEntity<>(headers);ResponseEntity<String> responseEntity = httpUtils.restTemplate.exchange(url, method, requestEntity,String.class);return responseEntity.getBody();}/*** @description type 1 contentType:application/x-www-form-urlencoded  2contentType:application/json(使用了@RequestBody接收参数)*/public static <T> String postRequest(String url,String token,Map<String, Object> queryParams,Integer type) {String result = "";HttpHeaders headers = new HttpHeaders();//是否携带tokenif (StringUtils.isNotEmpty(token)){headers.add(HttpHeaders.AUTHORIZATION, "Bearer "+token);}//post 请求2种方式if (Objects.equals(type,1)){headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);MultiValueMap<String, Object> map = new LinkedMultiValueMap<>();for (String key : queryParams.keySet()) {map.add(key,queryParams.get(key));}HttpEntity<MultiValueMap<String,Object>> formEntity = new HttpEntity<>(map, headers);result = httpUtils.restTemplate.postForObject(url, formEntity, String.class);}if (Objects.equals(type,2)){headers.setContentType(MediaType.APPLICATION_JSON);String params = JSON.toJSONString(queryParams);HttpEntity<String> formEntity = new HttpEntity<>(params, headers);result = httpUtils.restTemplate.postForObject(url, formEntity, String.class);}return result;}/*** 发送包含文件的表单数据的POST请求** @param data 表单数据，JSON格式的字符串* @param url  目标URL* @param file 要上传的文件*/public static String formDataSendPost(String data, String url,String fileKey,File file) {OkHttpClient okHttpClient = new OkHttpClient();String responseBody = null;try {// 创建Multipart请求体MultipartBody.Builder requestBodyBuilder = new MultipartBody.Builder().setType(MultipartBody.FORM);// 添加文本参数com.alibaba.fastjson2.JSONObject jsonObject = JSONObject.parseObject(data);for (Map.Entry<String, Object> entry : jsonObject.entrySet()) {requestBodyBuilder.addFormDataPart(entry.getKey(), entry.getValue().toString());}// 添加文件参数if (file != null) {String fileName = file.getName();RequestBody fileBody = RequestBody.create(okhttp3.MediaType.parse("application/octet-stream"), file);requestBodyBuilder.addFormDataPart(fileKey, fileName, fileBody);}RequestBody requestBody = requestBodyBuilder.build();// 创建请求Request request = new Request.Builder().url(url).post(requestBody).build();// 发送请求并获取响应Response response = okHttpClient.newCall(request).execute();if (response.isSuccessful()) {responseBody = response.body().string();log.info("数据发送成功：" + responseBody);} else {responseBody = "数据发送失败：" + response.code() + " " + response.message();log.error("数据发送失败：" + response.code() + " " + response.message());}} catch (IOException e) {e.printStackTrace();}return responseBody;}
}