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RestTemplate-调用远端接口应用场景

article 2025/1/22 7:51:04

环境准备: Springboot项目
RestTemplate注入到项目中

	@Configuration
	public class Config {
	
	    @Bean
	    public RestTemplate restTemplate() {
	        return new RestTemplate(new OkHttp3ClientHttpRequestFactory());
	    }
	}

案例一: 使用get调用远程接口: 地址如: http://xxxx.xxx.xxx/xxx?a=111&b=222

客户端-接口调用:

    @GetMapping("/test")
    public void getTest(){
        try{
            System.out.println("模拟get请求: map参数会追加到url后, 如: http://xxx?text=aaa&test2=bbb");
            Map<String,String> map = new HashMap<>();
            map.put("test","123");
            Map<String, Object> httpServer = RestTemplateUtils.getHttpServer("http://10.24.100.105:8080/request/getData", map);
            System.out.println("httpServer==>" + httpServer);
         }catch (Exception e) {
            e.printStackTrace();
        }
    }

客户端-工具类

@Component
public class RestTemplateUtils {

    @Autowired
    private static RestTemplate restTemplate;

    static {
        restTemplate = new RestTemplate();
    }
    public static Map<String,Object> getHttpServer(String baseUrl, Map<String, String> requestParams){
        Map<String,Object> responseBody = new HashMap<>();
        try{
            MultiValueMap<String, String> body = new LinkedMultiValueMap<>();
            requestParams.forEach((key, value) -> body.add(key, value));
            // 使用 UriComponentsBuilder 构建 URL，包含查询参数
            String url = UriComponentsBuilder.fromHttpUrl(baseUrl)
                    .queryParams(body)
                    .toUriString();

            // 发送 GET 请求并获取响应体（假设响应体是 JSON 格式）
            String response = restTemplate.getForObject(url, String.class);
            // 解析 JSON 响应为 Map（这里省略了错误处理逻辑）
            ObjectMapper objectMapper = new ObjectMapper();
            responseBody = objectMapper.readValue(response, HashMap.class);
        } catch (Exception e){
            e.printStackTrace();
        }
        return responseBody;
    }
}

服务端-接口提供:
由于参数在url后面所以.服务端在接收参数时需用@RequestParam(从url上获取参数)注解,而不是用@RequestBody(从body体中获取参数)注解

     @GetMapping("/getData")
     public Map<String,Object> getData(@RequestParam Map<String,Object> map) {
        // 逻辑处理
        return map;
     }

案例二: 使用post调用远程接口: 入参为map, 接口返回map

客户端-接口调用:

   @GetMapping("/test")
    public void getTest(){
        try{
           System.out.println("模拟post请求: 入参map,出参map");
            Map<String,Object> map2 = new HashMap<>();
            map2.put("test","123");
            Map<String, Object> postServer= RestTemplateUtils.postHttpServer("http://10.24.100.105:8080/request/postData", map2);
            System.out.println("postServer==>" + postServer);
         }catch (Exception e) {
            e.printStackTrace();
        }
    }

客户端-工具类:

@Component
public class RestTemplateUtils {

    @Autowired
    private static RestTemplate restTemplate;

    static {
        restTemplate = new RestTemplate();
    }
     public static Map<String,Object> postHttpServer(String uri, Map<String,Object> requestParams){
        try{
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.APPLICATION_JSON);
            HttpEntity entity = new HttpEntity(requestParams,headers);
            ResponseEntity<Map> response = restTemplate.exchange(uri, HttpMethod.POST, entity, Map.class);
            Map<String,Object> body = response.getBody();
            return body;
        } catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

服务端-接口提供:
此时直接用@RequestBody将入参映射到map中

    @PostMapping("/postData")
    public Map<String,Object> postData(@RequestBody Map<String,Object> map) {
        map.put("request methods:","postData");
        return map;
    }

案例三: 使用post调用远程接口: 入参为map+file流文件, 接口返回map

在配置文件中添加如下属性: 防止报错The field files exceeds its maximum permitted size of 1048576 bytes.

spring.servlet.multipart.max-file-size=10MB
spring.servlet.multipart.max-request-size=100MB

客户端-接口调用:

    @GetMapping("/test")
    public void getTest(){
        try{
            System.out.println("模拟post请求: 入参map + file文件,出参map");
            Map<String,Object> map3 = new HashMap<>();
            map3.put("test","123");
            Map<String, Object> postfile= RestTemplateUtils.postHttpServerFile(postfileuri, map3,
                    Arrays.asList(new File("C:\\Users\\admin\\Desktop\\Docker安装mysql.docx")
                            ));
            System.out.println("postfile" + postfile);
         }catch (Exception e) {
            e.printStackTrace();
        }
    }

客户端-工具类:

@Component
public class RestTemplateUtils {

    @Autowired
    private static RestTemplate restTemplate;

    static {
        restTemplate = new RestTemplate();
    }

	public static Map<String,Object> postHttpServerFile(String uri, Map<String,Object> requestParams, List<File> files ){
        try{
            // 构建 MultiValueMap
            MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
            // 添加文件
            for (int i = 0; i < files.size(); i++) {
                FileSystemResource fileResource = new FileSystemResource(files.get(i));
                body.add("file", fileResource);
            }
            // 将参数添加到MultiValueMap体内
            requestParams.forEach((key, value) -> body.add(key, value));

            // 设置请求头
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.MULTIPART_FORM_DATA);
            // 创建 HttpEntity，使用 MultiValueMap 作为请求体
            HttpEntity<MultiValueMap<String, Object>> entity = new HttpEntity(body,headers);
            // 发送请求,并获取响应
            ResponseEntity<Map> response = restTemplate.exchange(uri, HttpMethod.POST, entity, Map.class);
            Map<String,Object> responseBody = response.getBody();
            return responseBody;
        } catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    
}

服务端-接口提供:
这里的file文件和参数都需要用@RequestParam 来映射接收

@PostMapping("/postDatafile")
    public Map<String,Object> postData(@RequestParam("file") MultipartFile[] file, @RequestParam Map<String,Object> map) {
        map.put("request methods:","postDatafile");
        map.put("fileName",file[0].getName());
        map.put("getBytes",file[0].getSize());
        return map;
    }

案例四: 使用post调用远程接口: 入参为map, 接口返回map+file流文件

客户端:

客户端-接口调用:
请求远端地址, 并将返回的file文件缓存到本地响应

    @GetMapping("/test")
    public void getTest(){
 System.out.println("模拟post请求: 入参map,出参file");
            Map<String,Object> queryParam = new HashMap<>();
            queryParam.put("id","123");
            File file = RestTemplateUtils.postHttpServerGetFile("http://10.24.146.105:8080/request/downloadFile", queryParam);
            // 将file写入到本地,
            // 创建File对象表示目标文件
            File targetFile = new File("C:\\Users\\admin\\Desktop\\test\\" + file.getName());
            try (
                    // 创建输入流读取源文件
                    FileInputStream fis = new FileInputStream(file);
                    // 创建输出流写入目标文件
                    FileOutputStream fos = new FileOutputStream(targetFile);
            ) {
                // 缓冲区
                byte[] buffer = new byte[1024];
                int bytesRead;
                // 循环读取源文件内容并写入目标文件
                while ((bytesRead = fis.read(buffer)) != -1) {
                    fos.write(buffer, 0, bytesRead);
                }
                System.out.println("文件已成功复制到目标目录。");
            } catch (IOException e) {
                e.printStackTrace();
            }

        }catch (Exception e) {
            e.printStackTrace();
        }
    }

客户端-工具类:

@Component
public class RestTemplateUtils {

    @Autowired
    private static RestTemplate restTemplate;

    static {
        restTemplate = new RestTemplate();
    }
    /**
     * post请求远端接口返回File
     * @param uri
     * @param requestParams
     * @return file
     */
    public static File postHttpServerGetFile(String uri, Map<String,Object> requestParams){
        File tempFile = null;
        try{
            HttpHeaders headers = new HttpHeaders();
            HttpEntity entity = new HttpEntity(requestParams,headers);
            ResponseEntity<Resource> response = restTemplate.exchange(uri, HttpMethod.POST, entity, Resource.class);
            // 检查响应状态码
            if (response.getStatusCode().is2xxSuccessful()) {
                Resource resource = response.getBody();
                try (InputStream inputStream = resource.getInputStream()) {
                    // 提取文件名
                    String fileName = resource.getFilename();
                    if (fileName != null && !fileName.isEmpty()) {
                        tempFile = new File(URLDecoder.decode(fileName, "UTF-8"));
                            tempFile.deleteOnExit(); // JVM退出时删除临时文件
                            // 将输入流写入到临时文件中
                            try (FileOutputStream outputStream = new FileOutputStream(tempFile)) {
                                byte[] buffer = new byte[1024];
                                int bytesRead;
                                while ((bytesRead = inputStream.read(buffer)) != -1) {
                                    outputStream.write(buffer, 0, bytesRead);
                                }
                            }
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } else {
                // 处理错误响应
                System.err.println("Request failed with status code: " + response.getStatusCode());
            }
        } catch(Exception e) {
            e.printStackTrace();
        }
        return tempFile;
    }
}

服务端-接口提供:
服务器端设置一个文件, 需要将文件名称设置的headers内,方便调用方使用

@PostMapping("/downloadFile")
    public ResponseEntity<InputStreamResource> downloadfile(@RequestBody Map<String,Object> map) {
        try{
            // 在这里，你可以根据传入的参数 params 来生成或获取文件内容
            System.out.println("入参:" + map);
            // 例如，你可以根据参数来查询数据库，获取文件的字节数据，或者生成一个新的文件

            // 为了演示，我们引入了一个本地文件流
            File file = new File("C:\\Users\\admin\\Desktop\\Docker安装mysql.docx");
            // 设置响应头
            HttpHeaders headers = new HttpHeaders();
            headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + URLEncoder.encode(file.getName(), "UTF-8") + "\"");
            headers.setContentType(MediaType.parseMediaType("application/vnd.openxmlformats-officedocument.wordprocessingml.document"));
            // 创建响应实体
            InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
            return new ResponseEntity<>(resource, headers, HttpStatus.OK);
        } catch (Exception e) {
            e.printStackTrace();
            return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

完整代码:工具类

package com.ht.common.utils;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.http.*;
import org.springframework.mock.web.MockMultipartFile;
import org.springframework.stereotype.Component;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;

import java.io.*;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.nio.file.Files;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 链接远端接口
 */
@Component
public class RestTemplateUtils {

    @Autowired
    private static RestTemplate restTemplate;

    static {
        restTemplate = new RestTemplate();
    }



    /**
     * get请求,入参是map,出参也是map, 由于是get请求,没有请求体,参数会被封装到url后面
     * @param baseUrl
     * @param requestParams
     * @return
     */
    public static Map<String,Object> getHttpServer(String baseUrl, Map<String, String> requestParams){
        Map<String,Object> responseBody = new HashMap<>();
        try{
            MultiValueMap<String, String> body = new LinkedMultiValueMap<>();
            requestParams.forEach((key, value) -> body.add(key, value));
            // 使用 UriComponentsBuilder 构建 URL，包含查询参数
            String url = UriComponentsBuilder.fromHttpUrl(baseUrl)
                    .queryParams(body)
                    .toUriString();

            // 发送 GET 请求并获取响应体（假设响应体是 JSON 格式）
            String response = restTemplate.getForObject(url, String.class);
            // 解析 JSON 响应为 Map（这里省略了错误处理逻辑）
            ObjectMapper objectMapper = new ObjectMapper();
            responseBody = objectMapper.readValue(response, HashMap.class);
        } catch (Exception e){
            e.printStackTrace();
        }
        return responseBody;
    }

    /**
     * get请求: 参数会封装在HttpEntity
     * @param baseUrl http://xxx
     * @param requestParams 请求参数
     * @return map
     */
    public static Map<String,Object> getHttpServer2(String baseUrl, Map<String, String> requestParams){
        try{
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.APPLICATION_JSON);
            HttpEntity entity = new HttpEntity(requestParams,headers);
            ResponseEntity<Map> response = restTemplate.exchange(baseUrl, HttpMethod.GET, entity, Map.class);
            Map<String,Object> body = response.getBody();
            return body;
        } catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    /**
     * http post请求
     * @param uri 远程地址
     * @param requestParams 请求参数
     * @return 返回值
     *
     服务端接口定义
     @PostMapping("/add")
     public Map<String,Object> add(@RequestBody Map<String,Object> map) {
        // 程序处理
        return new HashMap();
     }
     */
    public static Map<String,Object> postHttpServer(String uri, Map<String,Object> requestParams){
        try{
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.APPLICATION_JSON);
            HttpEntity entity = new HttpEntity(requestParams,headers);
            ResponseEntity<Map> response = restTemplate.exchange(uri, HttpMethod.POST, entity, Map.class);
            Map<String,Object> body = response.getBody();
            return body;
        } catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * http post请求,携带多个文件+请求参数
     * @param uri 远程地址
     * @param requestParams 请求参数
     * @param files 文件对象
     * @return 返回值
     服务端接口写法:
     @PostMapping("/postDatafile")
     public Map<String,Object> postData(@RequestParam("file") MultipartFile[] file, @RequestParam Map<String,Object> map) {
     map.put("request methods:","postDatafile");
     map.put("fileName",file[0].getName());
     map.put("getBytes",file[0].getSize());
     return map;
     }
     */
    public static Map<String,Object> postHttpServerFile(String uri, Map<String,Object> requestParams, List<File> files ){
        try{
            // 构建 MultiValueMap
            MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
            // 添加文件
            for (int i = 0; i < files.size(); i++) {
                FileSystemResource fileResource = new FileSystemResource(files.get(i));
                body.add("files", fileResource);
            }
            // 将参数添加到MultiValueMap体内
            requestParams.forEach((key, value) -> body.add(key, value));

            // 设置请求头
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.MULTIPART_FORM_DATA);
            // 创建 HttpEntity，使用 MultiValueMap 作为请求体
            HttpEntity<MultiValueMap<String, Object>> entity = new HttpEntity(body,headers);
            // 发送请求,并获取响应
            ResponseEntity<Map> response = restTemplate.exchange(uri, HttpMethod.POST, entity, Map.class);
            Map<String,Object> responseBody = response.getBody();
            return responseBody;
        } catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    
    /**
     * post请求远端接口返回File
     * @param uri
     * @param requestParams
     * @return file
     */
    public static File postHttpServerGetFile(String uri, Map<String,Object> requestParams){
        File tempFile = null;
        try{
            HttpHeaders headers = new HttpHeaders();
            HttpEntity entity = new HttpEntity(requestParams,headers);
            ResponseEntity<Resource> response = restTemplate.exchange(uri, HttpMethod.POST, entity, Resource.class);
            // 检查响应状态码
            if (response.getStatusCode().is2xxSuccessful()) {
                Resource resource = response.getBody();
                try (InputStream inputStream = resource.getInputStream()) {
                    // 提取文件名
                    String fileName = resource.getFilename();
                    if (fileName != null && !fileName.isEmpty()) {
                        tempFile = new File(URLDecoder.decode(fileName, "UTF-8"));
                            tempFile.deleteOnExit(); // JVM退出时删除临时文件
                            // 将输入流写入到临时文件中
                            try (FileOutputStream outputStream = new FileOutputStream(tempFile)) {
                                byte[] buffer = new byte[1024];
                                int bytesRead;
                                while ((bytesRead = inputStream.read(buffer)) != -1) {
                                    outputStream.write(buffer, 0, bytesRead);
                                }
                            }
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } else {
                // 处理错误响应
                System.err.println("Request failed with status code: " + response.getStatusCode());
            }
        } catch(Exception e) {
            e.printStackTrace();
        }
        return tempFile;
    }
}

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