为什么servlet不在多部分请求中找到FileItem？ [英] Why doesn't servlet find FileItem in multipart request?
问题描述
我编写了一个使用Apache commons文件上传库处理文件上传的Servlet。以下是一些代码：
I've written a Servlet that handles file uploads using the Apache commons file upload library. Here is some of the code:
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if (isMultipart) {
try {
DiskFileItemFactory fileItemFactory = new DiskFileItemFactory();
// Set size threshold for storing upload
fileItemFactory.setSizeThreshold(1 * 1024 * 50); // 50 KB
// Set temporary directory to store uploaded files above threshold size
fileItemFactory.setRepository(new File(TEMP_DIRECTORY));
ServletFileUpload upload = new ServletFileUpload(fileItemFactory);
//HashMap<String, String> params = new HashMap<String, String>();
FileItemIterator iterator = upload.getItemIterator(request);
upload.setSizeMax(REQUEST_MAX_SIZE);
List items = upload.parseRequest(request);
Iterator it = items.iterator();
while (it.hasNext()) {
FileItem item = (FileItem) it.next();
if(item.isFormField()) {
} else {
String contentType = item.getContentType();
String fileName = item.getName();
String fieldName = item.getFieldName();
boolean isInMemory = item.isInMemory();
long sizeInBytes = item.getSize();
File uploadedFile = new File(PATH + "new_audio1.amr");
item.write(uploadedFile);
System.out.println("Field: " + fieldName);
System.out.println("File name: " + fileName);
System.out.println("Size: " + sizeInBytes);
System.out.println("Is in memory:" + isInMemory);
}
}
} catch (Exception ex) {
throw new ServletException(ex);
}
} else {
throw new ServletException();
}
由于某些原因让我失去了List'items'是空的所以我可以抓住上传的文件。
For some reason that escapes me the List 'items' is empty so I can't grab the uploaded file.
对于上传本身，我写了一些java代码：
For the upload itself, I've written some java code:
File audioFile = new File("C:\\Users\\Soto\\Desktop\\test recording.amr");
String url = "http://localhost:8080/AudioFileUpload/UploadServlet";
String charset = "UTF-8";
// random values
String latitude = "145";
String longitude = "132";
String speed = "0";
String query;
try {
query = String.format("latitude=%s&longitude=%s&speed=%s", URLEncoder.encode(latitude, charset), URLEncoder.encode(longitude, charset), URLEncoder.encode(speed, charset));
} catch (UnsupportedEncodingException e) {
query = String.format("latitude=%s&longitude=%s&speed=%s", latitude, longitude, speed);
}
HttpClient httpClient = new DefaultHttpClient();
httpClient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);
HttpPost httpPost = new HttpPost(url + "?" + query);
MultipartEntity mpEntity = new MultipartEntity();
ContentBody cbFile = new FileBody(audioFile, "audio/AMR");
mpEntity.addPart("audioFile", cbFile);
httpPost.setEntity(mpEntity);
HttpResponse response = null;
try {
response = httpClient.execute(httpPost);
HttpEntity responseEntity = response.getEntity();
System.out.println(response.getStatusLine());
if(responseEntity != null)
System.out.println(EntityUtils.toString(responseEntity));
if(responseEntity != null) {
EntityUtils.consume(responseEntity);
}
httpClient.getConnectionManager().shutdown();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
我觉得这个文件正在被正确附加和上传。
我也试过通过HTML进行多部分/表格数据发布请求，但是文件仍未找到。
It feels to me like the file is being attached and uploaded correctly. I also tried doing it through HTML with a multipart/form-data post request, but the file still wasn't found.
我做错了什么？
编辑：
我删除了doPost（）开头的行以及if语句：
I removed the line at the beginning of the doPost() along with the if statement:
ServletFileUpload.isMultipartContent(request);
然后上传工作正常。这种方法是否有可能消耗请求的'输入/输出/无论是什么'流？
And then the upload worked correctly. Is it possible that this method consumes the request's 'input/output/whatever it is' stream?
谢谢
推荐答案
编辑：我删除了doPost（）开头的行以及if语句：
I removed the line at the beginning of the doPost() along with the if statement:
ServletFileUpload.isMultipartContent(request);
然后上传工作正常。这种方法是否有可能消耗请求的'输入/输出/无论是什么'流？
And then the upload worked correctly. Is it possible that this method consumes the request's 'input/output/whatever it is' stream?
这很奇怪。所有方法都是检查请求方法是否等于 POST ，以及 Content-Type 标头是否以<$开头C $ C>多部分/ 。以下是当前最新Commons FileUpload API版本源代码的摘录（多年来没有太大变化）：
This is strange. All that method does is checking if the request method equals to POST and if the Content-Type header starts with multipart/. Here's an extract of the source of the currently latest Commons FileUpload API version (which hasn't changed much across years):
public static final boolean isMultipartContent(
HttpServletRequest request) {
if (!"post".equals(request.getMethod().toLowerCase())) {
return false;
}
String contentType = request.getContentType();
if (contentType == null) {
return false;
}
if (contentType.toLowerCase().startsWith(MULTIPART)) {
return true;
}
return false;
}
你看，没有什么令人震惊的。
You see, nothing shocking.
也许你正在使用一个非常模糊/错误的servlet容器，它表示当你调用 request.getMethod（）时会隐式消耗请求体的错误或 getContentType（）。
Perhaps you're using a very obscure/buggy servlet container which manifests a bug that the request body will implicitly be consumed when you call request.getMethod() or getContentType().
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