Question

首先，我问了这个问题What did I miss to send a http part post request，似乎我不理解从客户端向服务器发送multipart的逻辑。使用这篇文章https://developer.constantcontact.com/docs/mylibrary-files-api/file-add-multipart-post.html，我无法看到每个部分中的必填字段。

我构建了我的请求并添加了所有必填字段，如您所见

HttpClient client = HttpClientBuilder.create().build();
        HttpPost httpPost = new HttpPost(
                "http://localhost:8080/ServletExample1/multipart1");
        httpPost.addHeader("Content-Type",
                "multipart/related; boundary=HereItGoes");
        httpPost.addHeader("Accept", MediaType.TEXT_PLAIN);
        MultipartEntityBuilder builder = MultipartEntityBuilder.create();
        FileBody bin = new FileBody(new File("./test.txt"));
        builder.addPart("source", new StringBody("MyComputer",
                ContentType.TEXT_PLAIN));
        builder.addPart("folder_id", new StringBody("-1",
                ContentType.TEXT_PLAIN));
        builder.addPart("file_type", new StringBody("txt",
                ContentType.TEXT_PLAIN));
        builder.addPart("file_name", new StringBody("test.txt",
                ContentType.TEXT_PLAIN));
        builder.addPart("description", new StringBody("The file to test",
                ContentType.TEXT_PLAIN));
        builder.addPart("data", bin);
        HttpEntity entity = builder.build();
        httpPost.setEntity(entity);
        HttpResponse response = client.execute(httpPost);
        String responseString = new BasicResponseHandler()
                .handleResponse(response);
        System.out.println(responseString);

我的问题是在服务器中，我一直收到零件的数量为零。对于某些服务器没有收到部件的人（注意我并不是说服务器中有例外）

我这样说是因为在服务器（我的servlet）上我这样做

Iterator<Part> partsIterator = request.getParts().iterator();
            System.out.println("The number of parts is :"
                    + request.getParts().size());

并且打印结果始终为零，始终为

我错过了什么？

Answer 1

的Servlet＆＃39; multipart配置需要Content-Type multipart/form-data。

这是在javadoc of @MultipartConfig

中指定的

可以在javax.servlet.Servlet类上指定的注释，指示Servlet的实例期望符合要求的请求到multipart/form-data MIME类型。

您正在指定其他内容类型

httpPost.addHeader("Content-Type", "multipart/related; boundary=HereItGoes");

摆脱这个。 MultipartEntityBuilder已使用适当的标头构建请求。只需添加

builder.setBoundary("HereItGoes")

为边界。

示例Servlet

@WebServlet(loadOnStartup = 1, urlPatterns = "/multipart1")
@MultipartConfig()
public class MyServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("The number of parts is :" + request.getParts().size());
        Iterator<Part> partsIterator = request.getParts().iterator();
        while (partsIterator.hasNext()) {
            System.out.println(partsIterator.next().getName());
        }
    }
}

它会收到您发送的所有6个部分，并附有您问题中的代码。

Java servlet无法接收http post多部分请求的部分

1 个答案: