java文件上傳Demo(必看篇)

更新時(shí)間：2017年05月11日 07:46:28 投稿：jingxian

下面小編就為大家?guī)硪黄猨ava文件上傳Demo(必看篇)。小編覺得挺不錯(cuò)的，現(xiàn)在就分享給大家，也給大家做個(gè)參考。一起跟隨小編過來看看吧

說到文件上傳我們要做到：

1.引入兩個(gè)包：commons-fileupload-1.2.1.jar和commons-io-1.3.2.jar

2.將form改為上傳文件模式：enctype="multipart/form-data"

3.開始編寫相關(guān)代碼

這里會(huì)用到幾個(gè)關(guān)鍵的類：磁盤文件工廠DiskFileItemFactory ；創(chuàng)建servlet文件上傳類：ServletFileUpload

還有幾個(gè)重要的方法：DiskFileItemFactory類用于將以臨時(shí)文件形式保存在磁盤上的存放目錄的方法setRepository；

ServletFileUpload類得到表單中所有的數(shù)據(jù)，得到form表單中所有的元素方法：parseRequest

下面看具體代碼：

說明以這種方式上傳文件是保存在服務(wù)器端的！

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
 
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.FileUtils;
 
 
public class UploadServlet extends HttpServlet {
 
  /**
   * Constructor of the object.
   */
  public UploadServlet() {
    super();
  }
 
  /**
   * Destruction of the servlet. <br>
   */
  public void destroy() {
    super.destroy(); // Just puts "destroy" string in log
    // Put your code here
  }
 
  /**
   * The doGet method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to get.
   *
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
 
    this.doPost(request, response);
  }
 
  /**
   * The doPost method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to post.
   *
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
 
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    DiskFileItemFactory sf= new DiskFileItemFactory();//實(shí)例化磁盤被文件列表工廠
    String path = request.getRealPath("/upload");//得到上傳文件的存放目錄
    sf.setRepository(new File(path));//設(shè)置文件存放目錄
    sf.setSizeThreshold(1024*1024);//設(shè)置文件上傳小于1M放在內(nèi)存中
    String rename = "";//文件新生成的文件名
    String fileName = "";//文件原名稱
    String name = "";//普通field字段
    //從工廠得到servletupload文件上傳類
    ServletFileUpload sfu = new ServletFileUpload(sf);
     
    try {
      List<FileItem> lst = sfu.parseRequest(request);//得到request中所有的元素
      for (FileItem fileItem : lst) {
        if(fileItem.isFormField()){
          if("name".equals(fileItem.getFieldName())){
            name = fileItem.getString("UTF-8");
          }
        }else{
          //獲得文件名稱
          fileName = fileItem.getName();
          fileName = fileName.substring(fileName.lastIndexOf("\\")+1);
          String houzhui = fileName.substring(fileName.lastIndexOf("."));
          rename = UUID.randomUUID()+houzhui;
          fileItem.write(new File(path, rename));
        }
      }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
     
    System.out.println("普通字段"+name);
    System.out.println("文件名稱"+fileName);
    System.out.println("修改后生成的文件名稱"+rename);
    response.sendRedirect("ok.jsp");
    out.flush();
    out.close();
  }
 
  /**
   * Initialization of the servlet. <br>
   *
   * @throws ServletException if an error occurs
   */
  public void init() throws ServletException {
    // Put your code here
  }
 
}

index.jsp頁(yè)面：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>  
  <title>文件測(cè)試界面</title>
  <meta http-equiv="pragma" content="no-cache">
  <meta http-equiv="cache-control" content="no-cache">
  <meta http-equiv="expires" content="0">  
  <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  <meta http-equiv="description" content="This is my page">
 </head>
 <body>
  <div align="center">
  <form action="UploadServlet" enctype="multipart/form-data" method="post">
    名稱：<input name="name" /> <br>
    圖片：<input name="img" type="file"/><br>
    <input type="submit" value="提交" />  
    <input type="reset" value="重置" />
  </form>
  </div>
 </body>
</html>

ok.jsp頁(yè)面：

<body>
  <h1 align="center">上傳文件成功!</h1>
 </body>

實(shí)現(xiàn)效果就不截圖了，有需要自己那過去用！

以上這篇java文件上傳Demo(必看篇)就是小編分享給大家的全部?jī)?nèi)容了，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

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