java eclipse 中文件的上傳和下載示例解析
文件的上傳與下載（一）
在實現文件上傳和下載之前我們需要做一些準備工作，在Apache官網去下載文件上傳下載的兩個組件，下載鏈接這里給出：common-fileupload組件下載：http://commons.apache.org/proper/commons-fileupload/
common-io組件下載：http://commons.apache.org/proper/commons-io/根據自己需求下載對應版本
一、創建工程
將所需要的兩個開發包導入到工程項目中如圖：
二、代碼編寫
1.前端頁面代碼
1）. 在WebRoot目錄下新建一個fileUpload.jsp頁面，用來上傳文件
<%@ page language='java' import='java.util.*' pageEncoding='GB18030'%><%String path = request.getContextPath();String basePath = request.getScheme()+'://'+request.getServerName()+':'+request.getServerPort()+path+'/';%><!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01 Transitional//EN'><html> <head> <base href='http://www.b3g6.com/bcjs/<%=basePath%>'> <title>My JSP ’fileUpload.jsp’ starting page</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'> <!-- <link rel='stylesheet' type='text/css' href='http://www.b3g6.com/bcjs/styles.css'> --> </head> <body> <!-- 文件上傳表單的提交方式必須是“post” 編碼類型必須為：enctype='multipart/form-data' --> <form action='UploadServlet' method='post' enctype='multipart/form-data'> username: <input type='text' name='username' /><br> file: <input type='file' name='file'><br> file2: <input type='file' name='file2'><br> <input type='submit' value='上傳文件'> </form> </body></html>
2）.新建一個fileUploadResult.jsp頁面用來顯示結果信息
<%@ page language='java' import='java.util.*,java.io.*' pageEncoding='GB18030'%><%String path = request.getContextPath();String basePath = request.getScheme()+'://'+request.getServerName()+':'+request.getServerPort()+path+'/';%><!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01 Transitional//EN'><html> <head> <base href='http://www.b3g6.com/bcjs/<%=basePath%>'> <title>My JSP ’fileUploadResult.jsp’ starting page</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'> <!-- <link rel='stylesheet' type='text/css' href='http://www.b3g6.com/bcjs/styles.css'> --> </head> <body> <%-- <% //獲取流對象 InputStream inputStream = request.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(inputStream)); String buffer = null; while((buffer = br.readLine()) != null){ out.print(buffer + '<br>'); } br.close(); inputStream.close(); %> --%> ${message}<br> EL-username : ${requestScope.username} <br> EL-file1 : ${requestScope.file }<br> EL-file2 : ${requestScope.file2}<br> </body></html>
2. 編寫上傳文件處理的Servlet代碼
1) UploadServlet.java代碼如下：
package com.Servlet;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;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.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;public class UploadServlet extends HttpServlet { /** * 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 { //得到上傳文件的保存目錄，將上傳的文件放在webRoot目錄下（但是一般為了安全放在WEB-INF目錄下，不允許外界直接訪問，保證上傳的安全） String path = this.getServletContext().getRealPath('/upload'); File file = new File(path); //判斷上傳文件的保存目錄是否存在 if(!file.exists() && !file.isDirectory()){ System.out.println(path + '目錄不存在，需要創建！'); //創建目錄 file.mkdir(); } //消息提示 String message = ''; try{ //使用Apache文件上傳組件處理文件上傳步驟： //1.創建一個DiskFileItemFactory工廠 DiskFileItemFactory factory = new DiskFileItemFactory(); //2.創建一個文件上傳解析器 ServletFileUpload upload = new ServletFileUpload(factory); //解決中文亂碼 upload.setHeaderEncoding('UTF-8'); //3.判斷提交的數據普通表單的數據還是帶文件上傳的表單 if(!upload.isMultipartContent(request)){ //如果是表單數據普通表單,則按照傳統方式獲取數據 return ; } //4.使用ServletFileUpload解析器解析上傳數據，解析結果返回的是一個List<FileItem>集合，每一個FileItem對應一個Form表單的輸入項 List<FileItem> list = upload.parseRequest(request); for(FileItem item : list){ //如果fileItem中封裝的是普通輸入項的數據 if(item.isFormField()){ //獲取字段名字 String name = item.getFieldName(); //解決普通輸入項中中文亂碼問題 String value = item.getString('UTF-8');//value = new String(value.getBytes('iso8859-1'),'UTF-8'); System.out.println(name + ' = ' + value); }else{ //如果表單中提交的是上傳文件 //獲得上傳的文件名稱 String filename = item.getName(); System.out.println(filename); if(filename == null || filename.trim().equals(' ')){ continue; } //注意：不同的瀏覽器提交的文件名稱是不一樣的，有些瀏覽器提交的文件會帶有路徑，如“D:projectWebRoothello.jsp”，有一些是單純的文件名：hello.jsp //去掉獲取到文件名中的路徑名，保留單純的文件名 filename = filename.substring(filename.lastIndexOf('') + 1); //獲取item中的上傳文件的輸入流 InputStream in = item.getInputStream(); //創建一個文件輸入流 FileOutputStream out = new FileOutputStream(path + '' + filename); //創建一個緩沖區 byte buffer[] = new byte[1024]; //判斷輸入流中的數據是否已經讀取完畢的標志位 int len = 0; //循環將輸入流讀入到緩沖區當中，（len = in.read(buffer)>0）就表示in里面還有數據存在 while((len = in.read(buffer)) > 0){ //使用FileOutputStream輸出流將緩沖區的數據寫入到指定的目錄（path+''+filename）當中 out.write(buffer, 0, len); } //關閉輸入流 in.close(); //關閉輸出流 out.close(); //刪除處理文件上傳生成的臨時文件 item.delete(); message = '文件上傳成功!'; } } }catch(Exception e){ message = '文件上傳失敗！'; e.printStackTrace(); } request.setAttribute(message, message); request.getRequestDispatcher('fileUploadResult.jsp').forward(request, response); }}
2）web.xml文件中的配置
<?xml version='1.0' encoding='UTF-8'?><web-app version='3.0' xmlns='http://java.sun.com/xml/ns/javaee' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd'> <servlet> <servlet-name>UploadServlet</servlet-name> <servlet-class>com.Servlet.UploadServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>UploadServlet</servlet-name> <url-pattern>/UploadServlet</url-pattern> </servlet-mapping></web-app>
結果：
到此這篇關于eclipse java中文件的上傳和下載示例解析的文章就介紹到這了,更多相關eclipse java中文件的上傳和下載內容請搜索好吧啦網以前的文章或繼續瀏覽下面的相關文章希望大家以后多多支持好吧啦網！
相關文章：
網公網安備