Android Multipart POST到Google App Engine无效

Question

我正在开发一个Android程序,它通过POST与App Engine程序共享数据,所有这些都在java中.当我使用MultipartEntity POST时,appengine程序由于某些我无法弄清楚的原因而无法看到我的任何POST变量!

Appengine代码:

public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    resp.setContentType("text/plain");
    resp.getWriter().println("Output:");

    String mRoutine = req.getParameter("Routine");
    resp.getWriter().println("Routine: " + mRoutine);

    String mPMode = req.getParameter("PMode");
    resp.getWriter().println("PMode: " + mPMode);
}

使用Android代码段:

HttpPost post = new HttpPost("http://XXX.appspot.com/Echo");
HttpClient client = new DefaultHttpClient();
post.setEntity(new UrlEncodedFormEntity(data,HTTP.UTF_8));
HttpResponse response = client.execute(post);
HttpEntity resmarkMessagesReadFrom = response.getEntity();
if (resmarkMessagesReadFrom != null) {
    Result_STR= "Response:\n" + EntityUtils.toString(resmarkMessagesReadFrom);
    mMSGBox.setText(Result_STR);
}

失败的Android代码段:

HttpPost post = new HttpPost("http://XXX.appspot.com/Echo");
HttpClient client = new DefaultHttpClient();
MultipartEntity reqmarkMessagesReadFrom = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
try {
    reqmarkMessagesReadFrom.addPart("Routine", new StringBody("Neutral"));
    post.setEntity(reqmarkMessagesReadFrom);
    HttpResponse response = client.execute(post);
    HttpEntity resmarkMessagesReadFrom = response.getEntity();
    if (resmarkMessagesReadFrom != null) {
        Result_STR= "Response:\n" + EntityUtils.toString(resmarkMessagesReadFrom);
        mMSGBox.setText(Result_STR);
    }

Answer 1

使用MultipartEntity客户端上的类，您需要以不同的方式处理服务器端，使用Apache Commons FileUploaddoPost等 API 读取文件/参数。

Google App Engine 不允许写入文件系统，因此您需要使用 Streaming API。

import org.apache.commons.fileupload.FileItemStream;
import org.apache.commons.fileupload.FileItemIterator;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import java.io.InputStream;
..
public void doPost(HttpServletRequest req, HttpServletResponse res)
      throws ServletException, IOException {
    try {
      ServletFileUpload upload = new ServletFileUpload();
      res.setContentType("text/plain");

      FileItemIterator iterator = upload.getItemIterator(req);
      while (iterator.hasNext()) {
        String name = item.getFieldName();
        FileItemStream item = iterator.next();
        InputStream stream = item.openStream();

        if (item.isFormField()) {
          resp.getWriter().println((name + " : " + Streams.asString(stream));
        }
      }
    } catch (Exception ex) {
      throw new ServletException(ex);
    }
}