httpclient 如何上传附件

Httpclient 可以通过 MultipartEntityBuilder 来上传附件，示例代码如下：

CloseableHttpClient httpClient = HttpClients.createDefault();
HttpPost httpPost = new HttpPost(url);

MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);

File file = new File(filePath);
builder.addBinaryBody("file", file, ContentType.DEFAULT_BINARY, file.getName());

HttpEntity entity = builder.build();
httpPost.setEntity(entity);

HttpResponse response = httpClient.execute(httpPost);

其中，url 是上传接口的地址，filePath 是要上传的文件路径。通过 addBinaryBody 方法将文件添加到请求体中，然后将请求体设置到 HttpPost 中，最后执行请求即可。

相关问题

httpclient 下载附件

您可以使用 Apache HttpClient 库来下载附件。以下是一个示例代码：

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class AttachmentDownloader {
    public static void main(String[] args) {
        String attachmentUrl = "http://example.com/attachment.pdf";
        String savePath = "path/to/save/attachment.pdf";

        try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
            HttpGet httpGet = new HttpGet(attachmentUrl);
            HttpResponse response = httpClient.execute(httpGet);

            HttpEntity entity = response.getEntity();
            if (entity != null) {
                try (InputStream inputStream = entity.getContent();
                     OutputStream outputStream = new FileOutputStream(savePath)) {

                    byte[] buffer = new byte[1024];
                    int bytesRead;
                    while ((bytesRead = inputStream.read(buffer)) != -1) {
                        outputStream.write(buffer, 0, bytesRead);
                    }
                }
            }

            EntityUtils.consume(entity);
            System.out.println("Attachment downloaded successfully!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

请确保您已经导入 Apache HttpClient 的相关依赖。在上述示例中，您需要替换 `attachmentUrl` 为要下载的附件的 URL，`savePath` 为要保存附件的本地路径。执行代码后，附件将被下载并保存在指定的路径下。

注意：在实际应用中，您可能需要添加适当的错误处理和异常处理代码，以及合适的资源释放操作来确保代码的稳健性和可靠性。

springboot httpclient 调用第三方接口 上传附件 附件类型为multipartFile

好的，针对您的问题，您可以使用Spring的RestTemplate和MultipartHttpServletRequest类来实现上传附件的功能。具体实现步骤如下：

1. 在您的Spring Boot项目中添加以下依赖:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>  

2. 创建RestTemplate对象，并通过MultipartHttpServletRequest类构造HttpServletRequest对象，并将文件上传至第三方接口。代码示例如下：

RestTemplate restTemplate = new RestTemplate();

MultiValueMap<String, Object> bodyMap = new LinkedMultiValueMap<>();
bodyMap.add("file", new FileSystemResource(new File("文件路径")));

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);

HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(bodyMap, headers);

ResponseEntity<String> responseEntity = restTemplate.postForEntity("第三方接口地址", requestEntity, String.class);

String responseBody = responseEntity.getBody();

需要注意的是，文件的上传需要使用`FileSystemResource`或`ClassPathResource`等类来封装文件，同时需要在HttpHeaders中设置Content-Type为multipart/form-data。

希望这个回答对您有所帮助。