我正在为每个HTML表单使用一个公共Servlet，无论它是否有附件。

这个Servlet返回一个TreeMap，其中键是JSP名称参数，值是用户输入，并将所有附件保存在一个固定的目录中，稍后您可以根据自己的选择重命名目录。这里Connections是具有连接对象的自定义接口。

public class ServletCommonfunctions extends HttpServlet implements
        Connections {

    private static final long serialVersionUID = 1L;

    public ServletCommonfunctions() {}

    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response) throws ServletException,
                          IOException {}

    public SortedMap<String, String> savefilesindirectory(
            HttpServletRequest request, HttpServletResponse response)
            throws IOException {

        // Map<String, String> key_values = Collections.synchronizedMap(new
        // TreeMap<String, String>());
        SortedMap<String, String> key_values = new TreeMap<String, String>();
        String dist = null, fact = null;
        PrintWriter out = response.getWriter();
        File file;
        String filePath = "E:\\FSPATH1\\2KL06CS048\\";
        System.out.println("Directory Created   ????????????"
            + new File(filePath).mkdir());
        int maxFileSize = 5000 * 1024;
        int maxMemSize = 5000 * 1024;

        // Verify the content type
        String contentType = request.getContentType();
        if ((contentType.indexOf("multipart/form-data") >= 0)) {
            DiskFileItemFactory factory = new DiskFileItemFactory();
            // Maximum size that will be stored in memory
            factory.setSizeThreshold(maxMemSize);
            // Location to save data that is larger than maxMemSize.
            factory.setRepository(new File(filePath));
            // Create a new file upload handler
            ServletFileUpload upload = new ServletFileUpload(factory);
            // maximum file size to be uploaded.
            upload.setSizeMax(maxFileSize);
            try {
                // Parse the request to get file items.
                @SuppressWarnings("unchecked")
                List<FileItem> fileItems = upload.parseRequest(request);
                // Process the uploaded file items
                Iterator<FileItem> i = fileItems.iterator();
                while (i.hasNext()) {
                    FileItem fi = (FileItem) i.next();
                    if (!fi.isFormField()) {
                        // Get the uploaded file parameters
                        String fileName = fi.getName();
                        // Write the file
                        if (fileName.lastIndexOf("\\") >= 0) {
                            file = new File(filePath
                                + fileName.substring(fileName
                                        .lastIndexOf("\\")));
                        } else {
                            file = new File(filePath
                                + fileName.substring(fileName
                                        .lastIndexOf("\\") + 1));
                        }
                        fi.write(file);
                    } else {
                        key_values.put(fi.getFieldName(), fi.getString());
                    }
                }
            } catch (Exception ex) {
                System.out.println(ex);
            }
        }
        return key_values;
    }
}

对于Spring MVC

我设法有一个更简单的版本，用于获取表单输入，包括数据和图像。

<form action="/handleform" method="post" enctype="multipart/form-data">
    <input type="text" name="name" />
    <input type="text" name="age" />
    <input type="file" name="file" />
    <input type="submit" />
</form>

要处理的控制器

@Controller
public class FormController {
    @RequestMapping(value="/handleform",method= RequestMethod.POST)
    ModelAndView register(@RequestParam String name, @RequestParam int age, @RequestParam MultipartFile file)
            throws ServletException, IOException {

        System.out.println(name);
        System.out.println(age);
        if(!file.isEmpty()){
            byte[] bytes = file.getBytes();
            String filename = file.getOriginalFilename();
            BufferedOutputStream stream =new BufferedOutputStream(new FileOutputStream(new File("D:/" + filename)));
            stream.write(bytes);
            stream.flush();
            stream.close();
        }
        return new ModelAndView("index");
    }
}

HTML页面

<html>
    <head>
        <title>File Uploading Form</title>
    </head>

    <body>
        <h3>File Upload:</h3>
        Select a file to upload: <br />
        <form action="UploadServlet" method="post"
              enctype="multipart/form-data">

            <input type="file" name="file" size="50" />
            <br />
            <input type="submit" value="Upload File" />
        </form>
    </body>
</html>

Servlet文件

// Import required java libraries
import java.io.*;
import java.util.*;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.output.*;

public class UploadServlet extends HttpServlet {

    private boolean isMultipart;
    private String filePath;
    private int maxFileSize = 50 * 1024;
    private int maxMemSize = 4 * 1024;
    private File file;

    public void init() {
        // Get the file location where it would be stored.
        filePath =
               getServletContext().getInitParameter("file-upload");
    }

    public void doPost(HttpServletRequest request,
                       HttpServletResponse response)
               throws ServletException, java.io.IOException {

        // Check that we have a file upload request
        isMultipart = ServletFileUpload.isMultipartContent(request);
        response.setContentType("text/html");
        java.io.PrintWriter out = response.getWriter();
        if (!isMultipart) {
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet upload</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<p>No file uploaded</p>");
            out.println("</body>");
            out.println("</html>");
            return;
        }

        DiskFileItemFactory factory = new DiskFileItemFactory();
        // Maximum size that will be stored in memory
        factory.setSizeThreshold(maxMemSize);
        // Location to save data that is larger than maxMemSize.
        factory.setRepository(new File("c:\\temp"));

        // Create a new file upload handler
        ServletFileUpload upload = new ServletFileUpload(factory);
        // maximum file size to be uploaded.
        upload.setSizeMax(maxFileSize);

        try {
            // Parse the request to get file items.
            List fileItems = upload.parseRequest(request);

            // Process the uploaded file items
            Iterator i = fileItems.iterator();

            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet upload</title>");
            out.println("</head>");
            out.println("<body>");
            while (i.hasNext())
            {
                FileItem fi = (FileItem)i.next();
                if (!fi.isFormField())
                {
                     // Get the uploaded file parameters
                     String fieldName = fi.getFieldName();
                     String fileName = fi.getName();
                     String contentType = fi.getContentType();
                     boolean isInMemory = fi.isInMemory();
                     long sizeInBytes = fi.getSize();

                     // Write the file
                     if (fileName.lastIndexOf("\\") >= 0) {
                         file = new File(filePath +
                         fileName.substring(fileName.lastIndexOf("\\")));
                     }
                     else {
                         file = new File(filePath +
                         fileName.substring(fileName.lastIndexOf("\\") + 1));
                     }
                     fi.write(file);
                     out.println("Uploaded Filename: " + fileName + "<br>");
                }
            }
            out.println("</body>");
            out.println("</html>");
        }
        catch(Exception ex) {
            System.out.println(ex);
        }
    }

    public void doGet(HttpServletRequest request,
                        HttpServletResponse response)
            throws ServletException, java.io.IOException {

        throw new ServletException("GET method used with " +
                 getClass().getName() + ": POST method required.");
    }
}

文件web . xml

编译上面的servlet UploadServlet并在web.xml文件中创建所需的条目，如下所示。

<servlet>
   <servlet-name>UploadServlet</servlet-name>
   <servlet-class>UploadServlet</servlet-class>
</servlet>

<servlet-mapping>
   <servlet-name>UploadServlet</servlet-name>
   <url-pattern>/UploadServlet</url-pattern>
</servlet-mapping>

如果你碰巧使用Spring MVC，这是如何(我把它留在这里，以防有人发现它有用):

使用一个enctype属性设置为"multipart/form-data"的表单(与BalusC的答案相同):

<form action="upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file" />
    <input type="submit" value="Upload"/>
</form>

在控制器中，将请求参数文件映射为MultipartFile类型，如下所示:

@RequestMapping(value = "/upload", method = RequestMethod.POST)
public void handleUpload(@RequestParam("file") MultipartFile file) throws IOException {
    if (!file.isEmpty()) {
            byte[] bytes = file.getBytes(); // alternatively, file.getInputStream();
            // application logic
    }
}

你可以使用MultipartFile的getOriginalFilename()和getSize()来获取文件名和大小。

我已经用Spring版本4.1.1.RELEASE测试了这个功能。

下面是一个使用apache common -fileupload的例子:

// apache commons-fileupload to handle file upload
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setRepository(new File(DataSources.TORRENTS_DIR()));
ServletFileUpload fileUpload = new ServletFileUpload(factory);

List<FileItem> items = fileUpload.parseRequest(req.raw());
FileItem item = items.stream()
  .filter(e ->
  "the_upload_name".equals(e.getFieldName()))
  .findFirst().get();
String fileName = item.getName();

item.write(new File(dir, fileName));
log.info(fileName);

对于文件和输入控件，我能想到的最简单的方法是:

  <%
      if (request.getContentType() == null)
          return;
      // For input type=text controls
      String v_Text =
          (new BufferedReader(new InputStreamReader(request.getPart("Text1").getInputStream()))).readLine();

      // For input type=file controls
      InputStream inStr = request.getPart("File1").getInputStream();
      char charArray[] = new char[inStr.available()];
      new InputStreamReader(inStr).read(charArray);
      String contents = new String(charArray);
  %>