spring下的restTemplate使用

首先上配置，由于restTemplate不支持一些返回格式，所以需要自己手动配置

/**
 * @Description : restTemplate配置类
 * @Author : wzkris
 * @Version : V1.0.0
 * @Date : 2022/12/1 10:02
 */
@Configuration
public class RestTemplateConfig {

    @Bean
    public RestTemplate restTemplate() {
        OkHttp3ClientHttpRequestFactory factory = new OkHttp3ClientHttpRequestFactory();
        factory.setReadTimeout(3000);
        factory.setConnectTimeout(3000);
        RestTemplate restTemplate = new RestTemplate(factory);
        //增强转换器
        MappingJackson2HttpMessageConverter jackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
        //设置编码
        jackson2HttpMessageConverter.setDefaultCharset(StandardCharsets.UTF_8);
        jackson2HttpMessageConverter.setSupportedMediaTypes(Arrays.asList(
                MediaType.TEXT_HTML,
                MediaType.TEXT_PLAIN,
                MediaType.APPLICATION_OCTET_STREAM,
                MediaType.APPLICATION_JSON,
                MediaType.MULTIPART_FORM_DATA,
                MediaType.APPLICATION_XML));
        setMessageConverter(restTemplate, jackson2HttpMessageConverter);
        return restTemplate;
    }

    /**
     * 设置消息转换器
     */
    private void setMessageConverter(RestTemplate restTemplate, MappingJackson2HttpMessageConverter httpMessageConverter) {
        List<HttpMessageConverter<?>> messageConverters = restTemplate.getMessageConverters();
        Iterator<HttpMessageConverter<?>> iterator = messageConverters.iterator();
        while (iterator.hasNext()) {
            HttpMessageConverter<?> messageConverter = iterator.next();
            if (messageConverter instanceof MappingJackson2HttpMessageConverter) {
                iterator.remove();
                break;
            }
        }
        messageConverters.add(httpMessageConverter);
    }

}

用法懒得写，是个人都会，举个例子，下面的是我用restTemplate对接微信公众号的上传图片接口，可以看到传递的参数是图片，还需要设置请求头什么的，这个栗子都给出来了用法。

要注意的是，图片参数要用FileSystemResource来设置，而接口上接收文件的是MulltipartFile类型的参数，所以这里就会生成临时的file文件，等上传完毕再删掉即可

/**
     * 上传图片素材
     *
     * @param accessToken   token
     * @param multipartFile 图片
     * @return {
     * "url":  "http://mmbiz.qpic.cn/mmbiz/gLO17UPRQ/0"
     * }
     */
    public JSONObject uploadImage(String accessToken, MultipartFile multipartFile) {
        String url = "https://api.weixin.qq.com/cgi-bin/media/uploadimg?access_token=" + accessToken;
        //设置请求体，注意是LinkedMultiValueMap
        MultiValueMap<String, Object> data = new LinkedMultiValueMap<>();
        String path = GtConfig.getUploadPath() + multipartFile.getOriginalFilename();
        File file = new File(path);
        try {
            multipartFile.transferTo(file);
        } catch (IOException e) {
            throw new ServiceException(e.getMessage());
        }
        FileSystemResource media = new FileSystemResource(file);
        //设置上传文件
        data.add("media", media);
        //上传文件,设置请求头
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
        httpHeaders.setContentLength(multipartFile.getSize());
        HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(data, httpHeaders);
        //上传
        JSONObject jsonObject = restTemplate.postForObject(url, requestEntity, JSONObject.class);
        //然后删除临时文件
        file.delete();
        return jsonObject;
    }

然后测试，查看返回