以下servlet处理上传照片和该照片的标题。 servlet工作正常（将照片上传到请求的目录），直到添加处理相同from的文本字段的逻辑。现在它既没有上传照片也没有将标题提交给数据库。表单的内容类型为 multipart/form-data 。
HTML
<form method="post" action="UploadHandler" enctype="multipart/form-data">
<table>
<tr>
<td> <strong> Browse photo to submit </strong> </td>
<td> <input type="file" name="ImageToUpload" value="Upload Photo"/> </td>
</tr>
<tr>
<td> <strong> Give a Caption to this photo </strong> </td>
<td> <input type="text" name="CaptionBox" size="40" /></td>
</tr>
<tr>
<td> <strong> Tags <a href="#"> <i> Browse tags </i> </a> </strong> </td>
<td> <input type="text" size="20" value="Tags" id="tagfield" style="color: #A0A0A4; font-size:16px;" onfocus="emptyTheDefaultValue()"> </td>
</tr>
<tr colspan="2">
<td> <input type="submit" value="submit photo"/> </td>
</tr>
</table>
</form>
处理上传的Servlet
package projectcodes;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.File;
import java.util.List;
import java.util.Iterator;
import org.apache.commons.fileupload.*;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FilenameUtils;
import NonServletFiles.HandleCaption;
import NonServletFiles.ChangePartToString;
public class UploadHandler extends HttpServlet {
@Override
public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {
response.setContentType("text/plain");
String path = request.getParameter("ImageToUpload");
// Now handle the caption
// Note : They have a multipart/form-data request
// Using the servlet API 3.0
ChangePartToString cpts = new ChangePartToString(request.getPart("CaptionBox")); // get the CaptionBox part
String caption = null;
try {
caption = cpts.getValue();
System.out.println(caption); // <<-------- I get this value fine
}catch(Exception exc) {
exc.printStackTrace();
System.out.println(exc);
}
PrintWriter writer = response.getWriter();
try {
Boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if(!isMultipart) {
Boolean AttemptToUploadFile = true;
RequestDispatcher rd = request.getRequestDispatcher("portfolio_one.jsp");
request.setAttribute("UploadAttempt", AttemptToUploadFile);
rd.forward(request, response);
} else {
DiskFileItemFactory diskFileItem = new DiskFileItemFactory();
ServletFileUpload fileUpload = new ServletFileUpload(diskFileItem);
List list = null;
try {
list = fileUpload.parseRequest(request);
}catch(Exception exc) {
// Boolean AttemptToUploadFile = true;
// RequestDispatcher rd = request.getRequestDispatcher("portfolio_one.jsp");
// request.setAttribute("UploadAttempt", AttemptToUploadFile);
// rd.forward(request, response);
exc.printStackTrace();
System.out.println(exc);
}
Iterator iterator = list.iterator();
while(iterator.hasNext()) {
String emailOfTheUser = null;
FileItem fileItem = (FileItem)iterator.next();
if(!fileItem.isFormField()) {
String fieldName = fileItem.getFieldName();
String fileName = FilenameUtils.getName(fileItem.getName());
HttpSession session = request.getSession();
if(!session.isNew()) {
emailOfTheUser = (String)session.getAttribute("Email");
}
File file = new File("/home/non-admin/project uploads/project users/" + emailOfTheUser ,fileName);
fileItem.write(file);
// now since the file has been uploaded , upload the caption to the photo
System.out.println("THE CAPTION :" + caption);
HandleCaption hc = new HandleCaption(caption,emailOfTheUser,fileName);
hc.SubmitCaptionToTheDatabase(); // This calls invokes a method that submits a caption to the database
RequestDispatcher rd = request.getRequestDispatcher("portfolio_one.jsp");
String message = "File Uploaded successfully !";
request.setAttribute("SuccessMessage", message);
rd.forward(request, response);
}
}
}
}catch(Exception exc) {
exc.printStackTrace();
System.out.println(exc);
}
}
}
字幕字符串返回正常。可能是文件无法上传的原因。我没有看到服务器日志中抛出任何异常。
答案 0 :(得分：2)
您正在将Servlet 3.0内置多部分解析器与Apache Commons FileUpload混合使用。你不应该这样做。一旦请求主体被一个API解析，它就不能被另一个API解析。客户端不会多次重新发送相同的请求主体，因为服务器需要解析它。
删除Apache Commons FileUpload。在使用Servlet 3.0内置多部分解析器时，您不需要它。您只需要向servlet类添加@MultipartConfig注释，以使多部分解析器对于普通表单字段和文件字段都能正常工作。您也不应该使用getParameterXxx()方法。另请参阅How to upload files to server using JSP/Servlet?
这是必须重写代码，以便获得两个值：
@WebServlet("/UploadHandler")
@MultipartConfig
public class UploadHandler extends HttpServlet {
@Override
public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {
Part imageToUpload = request.getPart("ImageToUpload");
String imageFilename = getFilename(imageToUpload);
InputStream imageContent = imageToUpload.getInputStream();
String captionBox = getValue(request.getPart("CaptionBox"));
// ...
}
private static String getFilename(Part part) {
for (String cd : part.getHeader("content-disposition").split(";")) {
if (cd.trim().startsWith("filename")) {
String filename = cd.substring(cd.indexOf('=') + 1).trim().replace("\"", "");
return filename.substring(filename.lastIndexOf('/') + 1).substring(filename.lastIndexOf('\\') + 1); // MSIE fix.
}
}
return null;
}
private static String getValue(Part part) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(part.getInputStream(), "UTF-8"));
StringBuilder value = new StringBuilder();
char[] buffer = new char[1024];
for (int length = 0; (length = reader.read(buffer)) > 0;) {
value.append(buffer, 0, length);
}
return value.toString();
}
}