如何通过http客户端4.5.2发送POST请求

Question

我使用http客户端发送HTTP Post请求，如下所示。

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.2</version>
</dependency>
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpmime</artifactId>
    <version>4.5.2</version>
</dependency>

服务器需要一些params inclue：method（String），appKey（String），signMethod（String），img（byte []）..

我使用以下代码发送帖子，但响应显示：＆＃34;缺少必需的参数：img＆＃34;。

// append URL
String fullUrl = HttpRequestUtils.appendUrlRequestParams(API, params);

// builder request entity
MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create().setCharset(Charset.forName("UTF-8"));
for(Entry<String, String> entry : params.entrySet()) {
    multipartEntityBuilder.addTextBody(entry.getKey(), entry.getValue());
}
multipartEntityBuilder.addBinaryBody(PictureUploadConstant.img, imgs);
HttpEntity requestEntity = multipartEntityBuilder.build();

// post
HttpPost post = new HttpPost(fullUrl);
post.setEntity(requestEntity);

CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
try {
    // send post
    response = httpClient.execute(post);
    // response
    HttpEntity responseEntity = response.getEntity();
    String result = EntityUtils.toString(responseEntity);
    System.out.println("result" + result);
} catch (IOException e) {
    e.printStackTrace();
}

任何人都可以告诉我它有什么问题吗？