1. 通過getInputStream()取得上傳檔案。

/**
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package net.individuals.web.servlet;

import java.io.DataInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author Barudisshu
 */
@WebServlet(name = "UploadServlet", urlPatterns = {"/UploadServlet"})
public class UploadServlet extends HttpServlet {

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        //讀取請求Body
        byte[] body = readBody(request);
        //取得所有Body內容的字串表示
        String textBody = new String(body, "ISO-8859-1");
        //取得上傳的檔名稱
        String fileName = getFileName(textBody);
        //取得檔案開始與結束位置
        Position p = getFilePosition(request, textBody);
        //輸出至檔案
        writeTo(fileName, body, p);
    }

    //構造類
    class Position {

        int begin;
        int end;

        public Position(int begin, int end) {
            this.begin = begin;
            this.end = end;
        }
    }

    private byte[] readBody(HttpServletRequest request) throws IOException {
        //獲取請求文字位元組長度
        int formDataLength = request.getContentLength();
        //取得ServletInputStream輸入流物件
        DataInputStream dataStream = new DataInputStream(request.getInputStream());
        byte body[] = new byte[formDataLength];
        int totalBytes = 0;
        while (totalBytes < formDataLength) {
            int bytes = dataStream.read(body, totalBytes, formDataLength);
            totalBytes += bytes;
        }
        return body;
    }

    private Position getFilePosition(HttpServletRequest request, String textBody) throws IOException {
        //取得檔案區段邊界資訊
        String contentType = request.getContentType();
        String boundaryText = contentType.substring(contentType.lastIndexOf("=") + 1, contentType.length());
        //取得實際上傳檔案的氣勢與結束位置
        int pos = textBody.indexOf("filename=\"");
        pos = textBody.indexOf("\n", pos) + 1;
        pos = textBody.indexOf("\n", pos) + 1;
        pos = textBody.indexOf("\n", pos) + 1;
        int boundaryLoc = textBody.indexOf(boundaryText, pos) - 4;
        int begin = ((textBody.substring(0, pos)).getBytes("ISO-8859-1")).length;
        int end = ((textBody.substring(0, boundaryLoc)).getBytes("ISO-8859-1")).length;

        return new Position(begin, end);
    }

    private String getFileName(String requestBody) {
        String fileName = requestBody.substring(requestBody.indexOf("filename=\"") + 10);
        fileName = fileName.substring(0, fileName.indexOf("\n"));
        fileName = fileName.substring(fileName.indexOf("\n") + 1, fileName.indexOf("\""));

        return fileName;
    }

    private void writeTo(String fileName, byte[] body, Position p) throws IOException {
        FileOutputStream fileOutputStream = new FileOutputStream("e:/workspace/" + fileName);
        fileOutputStream.write(body, p.begin, (p.end - p.begin));
        fileOutputStream.flush();
        fileOutputStream.close();
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}
 

2. 通過getPart()、getParts()取得上傳檔案。

    body格式：

POST http://www.example.com HTTP/1.1 
Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryrGKCBY7qhFd3TrwA 

------WebKitFormBoundaryrGKCBY7qhFd3TrwA 
Content-Disposition: form-data; name="text" 

title 
------WebKitFormBoundaryrGKCBY7qhFd3TrwA 
Content-Disposition: form-data; name="file"; filename="chrome.png" 
Content-Type: image/png 

PNG ... content of chrome.png ... 
------WebKitFormBoundaryrGKCBY7qhFd3TrwA-- 
 

/**
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package net.individuals.web.servlet;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

/**
 *
 * @author Barudisshu
 */
@MultipartConfig
@WebServlet(name = "UploadServlet", urlPatterns = {"/UploadServlet"})
public class UploadServlet extends HttpServlet {

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        Part part = request.getPart("photo");
        String fileName = getFileName(part);
        writeTo(fileName, part);
    }

    //取得上傳檔名
    private String getFileName(Part part) {
        String header = part.getHeader("Content-Disposition");
        String fileName = header.substring(header.indexOf("filename=\"") + 10, header.lastIndexOf("\""));

        return fileName;
    }

    //儲存檔案
    private void writeTo(String fileName, Part part) throws IOException, FileNotFoundException {
        InputStream in = part.getInputStream();
        OutputStream out = new FileOutputStream("e:/workspace/" + fileName);
        byte[] buffer = new byte[1024];
        int length = -1;
        while ((length = in.read(buffer)) != -1) {
            out.write(buffer, 0, length);
        }

        in.close();
        out.close();
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }
}
 

3、另一種較為簡單的方法：採用part的wirte(String fileName)上傳，瀏覽器將產生臨時TMP檔案

/**
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package net.individuals.web.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

/**
 *採用part的wirte(String fileName)上傳，瀏覽器將產生臨時TMP檔案。
 * @author Barudisshu
 */
@MultipartConfig(location = "e:/workspace")
@WebServlet(name = "UploadServlet", urlPatterns = {"/UploadServlet"})
public class UploadServlet extends HttpServlet {

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //處理中文檔名
        request.setCharacterEncoding("UTF-8");
        Part part = request.getPart("photo");
        String fileName = getFileName(part);
        //將檔案寫入location指定的目錄
        part.write(fileName);
    }

    private String getFileName(Part part) {
        String header = part.getHeader("Content-Disposition");
        String fileName = header.substring(header.indexOf("filename=\"") + 10, header.lastIndexOf("\""));
        return fileName;
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}