RestTemplate是Spring提供的用于访问Rest服务的客户端，RestTemplate提供了多种便捷访问远程Http服务的方法,能够大大提高客户端的编写效率。

我基于RestTemplate编写了一个工具类，方便使用。工具类提供之提供了GET、POST、DELETE请求方法，其他方法自行补充

---

1. Application启动类中实例RestTemplate

   @SpringBootApplication
   @RestController
   public class Applicatiohexn {
       public static void main(String[] args) {
           SpringApplication.run(ElasticApplication.class, args);
       }
       @Bean
       public RestTemplate restTemplate() {
           // new HttpComponentsClientHttpRequestFactory()作用：支持patch请求
           RestTemplate restTemplate = new RestTemplate(new HttpComponentsClientHttpRequestFactory());
   //        restTemplate.getMessageConverters().set(1, new StringHttpMessageConverter(StandardCharsets.UTF_8));
           return restTemplate;
       }
   }

2. RestTemplateUtils工具类 点击下载

   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.http.HttpEntity;
   import org.springframework.http.HttpHeaders;
   import org.springframework.http.HttpMethod;
   import org.springframework.http.ResponseEntity;
   import org.springframework.stereotype.Component;
   import org.springframework.util.LinkedMultiValueMap;
   import org.springframework.util.MultiValueMap;
   import org.springframework.web.client.RestTemplate;
   
   import java.util.ArrayList;
   import java.util.LinkedHashMap;
   import java.util.List;
   import java.util.Map;
   
   /**
    * RestTemplate工具类
    *
    * @author Colin.Ye
    * @version 1.0
    * @ClassName RestTemplateUtils
    * @date 2019/7/31
    **/
   @Component
   public class RestTemplateUtils {
   
       @Autowired
       private RestTemplate restTemplate;
   
       /**
        * POST请求-JSON参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpPostJson(String url, Map params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           // json方式传参
           return restTemplate.postForObject(url, new HttpEntity(params, httpHeaders), clazz);
       }
   
       /**
        * POST请求-FROM参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpPostForm(String url, Map params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           params = params == null ? new LinkedHashMap<>() : params;
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           MultiValueMap<String, Object> stringObjectLinkedMultiValueMap = new LinkedMultiValueMap<>();
           params.forEach((o1, o2) -> stringObjectLinkedMultiValueMap.add(o1.toString(), o2));
           // 表单方式传参
           // json方式传参
           return restTemplate.postForObject(url, new HttpEntity(stringObjectLinkedMultiValueMap, httpHeaders), clazz);
       }
   
       /**
        * GET请求-?号参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpGetTraditional(String url, Map params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           params = params == null ? new LinkedHashMap<>() : params;
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           StringBuilder sb = new StringBuilder(url);
           sb.append("?");
           params.forEach((o1, o2) -> sb.append(o1).append("=").append(o2).append("&"));
           url = sb.toString().replaceAll("&$+|\\?$+", "");
           ResponseEntity<T> exchange = restTemplate.exchange(url, HttpMethod.GET, new HttpEntity(null, httpHeaders), clazz);
           return exchange.getBody();
       }
   
       /**
        * GET请求-分隔符参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpGetPlaceholder(String url, List params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           params = params == null ? new ArrayList<>() : params;
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           StringBuilder sb = new StringBuilder(url);
           params.forEach(o2 -> sb.append("/").append(o2));
           url = sb.toString().replaceAll("&$+|\\?$+", "");
           ResponseEntity<T> exchange = restTemplate.exchange(url, HttpMethod.GET, new HttpEntity(null, httpHeaders), clazz);
           return exchange.getBody();
       }
   
       /**
        * DELETE请求-?号参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpDeleteTraditional(String url, Map params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           params = params == null ? new LinkedHashMap<>() : params;
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           StringBuilder sb = new StringBuilder(url);
           sb.append("?");
           params.forEach((o1, o2) -> sb.append(o1).append("=").append(o2).append("&"));
           url = sb.toString().replaceAll("&$+|\\?$+", "");
           ResponseEntity<T> exchange = restTemplate.exchange(url, HttpMethod.DELETE, new HttpEntity(null, httpHeaders), clazz);
           return exchange.getBody();
       }
   
       /**
        * DELETE请求-分隔符参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpDeletePlaceholder(String url, List params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           params = params == null ? new ArrayList<>() : params;
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           StringBuilder sb = new StringBuilder(url);
           params.forEach(o2 -> sb.append("/").append(o2));
           url = sb.toString().replaceAll("&$+|\\?$+", "");
           ResponseEntity<T> exchange = restTemplate.exchange(url, HttpMethod.DELETE, new HttpEntity(null, httpHeaders), clazz);
           return exchange.getBody();
       }
   
       /**
        * PATCH请求-JSON参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpPatchJson(String url, Map params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           // json方式传参
           return restTemplate.patchForObject(url, new HttpEntity(params, httpHeaders), clazz);
       }
   
       /**
        * patch请求-FROM参数
        *
        * @param url
        * @param params
        * @param headers
        * @return
        */
       public <T> T httpPatchForm(String url, Map params, Map headers, Class<T> clazz) {
           HttpHeaders httpHeaders = new HttpHeaders();
           params = params == null ? new LinkedHashMap<>() : params;
           if (headers != null) {
               headers.forEach((o1, o2) -> httpHeaders.add(o1.toString(), o2.toString()));
           }
           MultiValueMap<String, Object> stringObjectLinkedMultiValueMap = new LinkedMultiValueMap<>();
           params.forEach((o1, o2) -> stringObjectLinkedMultiValueMap.add(o1.toString(), o2));
           // 表单方式传参
           // json方式传参
           return restTemplate.patchForObject(url, new HttpEntity(stringObjectLinkedMultiValueMap, httpHeaders), clazz);
       }
   }

3. 使用

   /**
    * @author Colin.Ye
    * @version 1.0
    * @ClassName LowCreateIndexDemo
    * @date 2019/3/13
    **/
   @RestController
   @RequestMapping("/lowClient/v1/")
   @CrossOrigin
   @DefaultProperties(defaultFallback = "defaultFallback")
   public class LowCreateIndexDemo extends BaseController {
   
       @Autowired
       private RestTemplateUtils restTemplateUtils;
   
       @RequestMapping("/index")
       @Log
       @HystrixCommand(commandProperties = @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000"))
   
       public String index() {
           Map<String, Object> params = new HashMap<>();
           //  上传文件
           FileSystemResource resource = new FileSystemResource(new File("/Users/yezhuang/Documents/data/oracle命令的副本.txt"));
           params.put("deviceId", "123424");
           params.put("file", resource);
           Object o = restTemplateUtils.httpPostFrom("http://localhost:10005/lowClient/v1/test", params, null, String.class);
           return o.toString();
       }
   
       @RequestMapping("/test")
       public String remoteUpdteTest(String deviceId, @RequestParam MultipartFile file) {
           System.out.println(deviceId);
           System.out.println(file.getName());
           return "success";
       }
   
       private String fallback() {
           return "网络开小差了，请稍后重试···";
       }
   
       private String defaultFallback() {
           return "defaultFallback: 网络开小差了，请稍后重试···";
       }
   }

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