HttpPost InputStream 上传文件封装方法

以下是一个封装方法，可以实现通过HttpPost上传文件：

public static String postFile(String url, File file) throws IOException {
    HttpPost post = new HttpPost(url);
    MultipartEntityBuilder builder = MultipartEntityBuilder.create();
    builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
    builder.addBinaryBody("file", file, ContentType.DEFAULT_BINARY, file.getName());
    HttpEntity entity = builder.build();
    post.setEntity(entity);
    CloseableHttpClient client = HttpClients.createDefault();
    CloseableHttpResponse response = client.execute(post);
    int statusCode = response.getStatusLine().getStatusCode();
    if (statusCode != HttpStatus.SC_OK) {
        throw new RuntimeException("请求失败，状态码为：" + statusCode);
    }
    HttpEntity responseEntity = response.getEntity();
    String result = EntityUtils.toString(responseEntity);
    EntityUtils.consume(entity);
    EntityUtils.consume(responseEntity);
    response.close();
    client.close();
    return result;
}

使用方法：

File file = new File("/path/to/file");
String url = "http://example.com/upload";
String result = postFile(url, file);
System.out.println(result);

其中，`url` 是上传接口的地址，`file` 是要上传的文件对象，`result` 是服务器返回的响应字符串。