文件的上傳

 

首先導入commons-io.jar和commons-fileuoload.jar兩個包

 代碼如下

 

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

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.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class FileUploadServlet extends HttpServlet {
 private static final long serialVersionUID = 1L;
 private String path1="d://user//";

 public FileUploadServlet() {
  super();
 }

 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doPost(request, response);
 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  final long MAX_SIZE = 3 * 1024 * 1024;// 設置上傳文件最大爲 3M
  // 允許上傳的文件格式的列表
  final String[] allowedExt = new String[] { "jpg", "jpeg", "gif", "txt",
    "doc", "docx", "mp3", "wma", "m4a" };
  response.setContentType("text/html");
  // 設置字符編碼爲UTF-8, 這樣支持漢字顯示
  response.setCharacterEncoding("UTF-8");

  // 實例化一個硬盤文件工廠,用來配置上傳組件ServletFileUpload
  DiskFileItemFactory dfif = new DiskFileItemFactory();
  dfif.setSizeThreshold(4096);// 設置上傳文件時用於臨時存放文件的內存大小,這裏是4K.多於的部分將臨時存在硬盤
  dfif.setRepository(new File(path1));// 設置存放臨時文件的目錄,web根目錄下的ImagesUploadTemp目錄

  // 用以上工廠實例化上傳組件
  ServletFileUpload sfu = new ServletFileUpload(dfif);
  sfu.setHeaderEncoding("utf-8");

  // 設置最大上傳尺寸
  sfu.setSizeMax(MAX_SIZE);

  PrintWriter out = response.getWriter();
  // 從request得到 所有 上傳域的列表
  List fileList = null;
  try {
   fileList = sfu.parseRequest(request);
  } catch (FileUploadException e) {// 處理文件尺寸過大異常
   if (e instanceof SizeLimitExceededException) {
    out.println("文件尺寸超過規定大小:" + MAX_SIZE + "字節<p />");
    out.println("<a href=/"upload.html/" target=/"_top/">返回</a>");
    return;
   }
   e.printStackTrace();
  }
  // 沒有文件上傳
  if (fileList == null || fileList.size() == 0) {
   out.println("請選擇上傳文件<p />");
   out.println("<a href=/"upload.html/" target=/"_top/">返回</a>");
   return;
  }
  // 得到所有上傳的文件
  Iterator fileItr = fileList.iterator();
  // 循環處理所有文件
  while (fileItr.hasNext()) {
   FileItem fileItem = null;
   String path = null;
   long size = 0;
   // 得到當前文件
   fileItem = (FileItem) fileItr.next();
   // 忽略簡單form字段而不是上傳域的文件域(<input type="text" />等)
   if (fileItem == null || fileItem.isFormField()) {
    continue;
   }
   // 得到文件的完整路徑
   path = fileItem.getName();
   System.out.println(path);
   // 得到文件的大小
   size = fileItem.getSize();
   if ("".equals(path) || size == 0) {
    out.println("請選擇上傳文件<p />");
    out.println("<a href=/"upload.html/" target=/"_top/">返回</a>");
    return;
   }

   // 得到去除路徑的文件名
   String t_name = path.substring(path.lastIndexOf("//") + 1);
   System.out.println(t_name);
   // 得到文件的擴展名(無擴展名時將得到全名)
   String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
   System.out.println(t_ext);
   // 拒絕接受規定文件格式之外的文件類型
   int allowFlag = 0;
   int allowedExtCount = allowedExt.length;
   for (; allowFlag < allowedExtCount; allowFlag++) {
    if (allowedExt[allowFlag].equals(t_ext))
     break;
   }
   if (allowFlag == allowedExtCount) {
    out.println("請上傳以下類型的文件<p />");
    for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
     out.println("*." + allowedExt[allowFlag]
       + "&nbsp;&nbsp;&nbsp;");
    out.println("<p /><a href=/"upload.html/" target=/"_top/">返回</a>");
    return;
   }

   long now = System.currentTimeMillis();
   // 根據系統時間生成上傳後保存的文件名
   String prefix = String.valueOf(now);
   // 保存的最終文件完整路徑,保存在web根目錄下的ImagesUploaded目錄下
   String u_name = path1+t_name;
   try {
    // 保存文件
    fileItem.write(new File(u_name));
    out.println("文件上傳成功. 已保存爲: " + prefix + "." + t_ext
      + " &nbsp;&nbsp;文件大小: " + size + "字節<p />");
    out.println("<a href=/"upload.html/" target=/"_top/">繼續上傳</a>");
   } catch (Exception e) {
    e.printStackTrace();
   }

  }

 }
 
 
 //初始化，銷燬方法

 public void init() throws ServletException {
  // Put your code here
 }
 public void destroy() {
  super.destroy(); // Just puts "destroy" string in log
  // Put your code here
 }
}