Servlet实现文件上传的三种方法总结

Servlet实现文件上传的三种方法总结

1. 通过getInputStream()取得上传文件。

/**
 * 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");
    //读取请求Body
    byte[] body = readBody(request);
    //取得所有Body内容的字符串表示
    String textBody = new String(body, "ISO-8859-1");
    //取得上传的文件名称
    String fileName = getFileName(textBody);
    //取得文件开始与结束位置
    Position p = getFilePosition(request, textBody);
    //输出至文件
    writeTo(fileName, body, p);
  } 

  //构造类
  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 {
    //获取请求文本字节长度
    int formDataLength = request.getContentLength();
    //取得ServletInputStream输入流对象
    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 {
    //取得文件区段边界信息
    String contentType = request.getContentType();
    String boundaryText = contentType.substring(contentType.lastIndexOf("=") + 1, contentType.length());
    //取得实际上传文件的气势与结束位置
    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. 通过getPart()、getParts()取得上传文件。

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--  

[html] view plain copy
/**
 * 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);
  } 

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

    return fileName;
  } 

  //存储文件
  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、另一种较为简单的方法：采用part的wirte(String fileName)上传，浏览器将产生临时TMP文件

/**
 * 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; 

/**
 *采用part的wirte(String fileName)上传，浏览器将产生临时TMP文件。
 * @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 {
    //处理中文文件名
    request.setCharacterEncoding("UTF-8");
    Part part = request.getPart("photo");
    String fileName = getFileName(part);
    //将文件写入location指定的目录
    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>
}

以上就是Servlet实现文件上传的实例，如有疑问请留言或者到本站社区交流讨论，感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！