为什么我的 Java HttpClient 文件上传到 PHP 失败，如何使用 MultipartEntity 修复它？

import java.io.File;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpVersion;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.mime.MultipartEntity;
import org.apache.http.entity.mime.content.ContentBody;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.CoreProtocolPNames;
import org.apache.http.util.EntityUtils;

public class PostFile {
    public static void main(String[] args) throws Exception {
        HttpClient httpclient = new DefaultHttpClient();
        httpclient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);

        HttpPost httppost = new HttpPost("http://localhost:9001/upload.php");
        File file = new File("c:/TRASH/zaba_1.jpg");

        MultipartEntity mpEntity = new MultipartEntity();
        ContentBody cbFile = new FileBody(file, "image/jpeg");
        mpEntity.addPart("userfile", cbFile);

        httppost.setEntity(mpEntity);
        System.out.println("executing request " + httppost.getRequestLine());
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity resEntity = response.getEntity();

        System.out.println(response.getStatusLine());
        if (resEntity != null) {
            System.out.println(EntityUtils.toString(resEntity));
        }
        if (resEntity != null) {
            resEntity.consumeContent();
        }

        httpclient.getConnectionManager().shutdown();
    }
}