我试图将图片从Android应用上传到我的服务器。发送＆＃39; httpPost＆＃39;似乎工作得很好，在服务器端代码，我在执行HTTPServletRequest.getPart（＆＃34; filepart＆＃34;）时得到null。
Android活动代码
public class ImageUpload extends Activity {
private static int RESULT_LOAD_IMAGE = 1;
Bitmap bm;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.image_upload);
Button buttonLoadImage = (Button) findViewById(R.id.buttonLoadPicture);
buttonLoadImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Intent i = new Intent(
Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(i, RESULT_LOAD_IMAGE);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK
&& null != data) {
Uri selectedImage = data.getData();
String[] filePathColumn = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(selectedImage,
filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String picturePath = cursor.getString(columnIndex);
cursor.close();
ImageView imageView = (ImageView) findViewById(R.id.imgView);
bm = BitmapFactory.decodeFile(picturePath);
imageView.setImageBitmap(bm);
SendHttpRequestTask t = new SendHttpRequestTask();
t.execute();
}
}
public void executeMultipartPost() {
}
private class SendHttpRequestTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
try {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bm.compress(CompressFormat.JPEG, 75, bos);
byte[] data = bos.toByteArray();
HttpClient httpClient = new DefaultHttpClient();
HttpPost postRequest = new HttpPost(
"http://192.168.43.85:8080/Albums/ImageUpload");
ByteArrayBody bab = new ByteArrayBody(data, "forest.jpg");
MultipartEntity reqEntity = new MultipartEntity();
reqEntity.addPart("userfile", bab);
postRequest.setEntity(reqEntity);
httpClient.execute(postRequest);
} catch (Exception e) {
// handle exception here
Log.e(e.getClass().getName(), e.getMessage());
}
return null;
}
}
}
我的服务器端代码
@WebServlet("/ImageUpload")
@MultipartConfig
public class ImageUpload extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ImageUpload() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
for (FileItem item : items) {
if (item.isFormField()) {
// Process regular form field (input type="text|radio|checkbox|etc", select, etc).
String fieldname = item.getFieldName();
String fieldvalue = item.getString();
// ... (do your job here)
} else {
// Process form file field (input type="file").
String fieldname = item.getFieldName();
InputStream filecontent = request.getPart("userfile").getInputStream();
OutputStream out = new FileOutputStream("C:\\test.jpg" );
IOUtils.copy(filecontent, out); // The function is below
out.flush();
out.close();
request.getRequestDispatcher("index.jsp").forward(request, response);
}
}
} catch (FileUploadException e) {
throw new ServletException("Cannot parse multipart request.", e);
}
}
}
执行此操作时，我在服务器端的getPart（）方法上获得了NullPointerException。感谢对此的任何帮助/建议。