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servlet文件上传及下载

發布時間：2024/8/26 编程问答 24 豆豆

生活随笔收集整理的這篇文章主要介紹了 servlet文件上传及下载小編覺得挺不錯的,現在分享給大家,幫大家做個參考.

servlet3.0中提供了對文件上傳的直接支持，不需要借助任何第三方上傳組件，直接使用Servlet3.0提供的API就能夠實現文件上傳功能。

servlet 代碼：

package ni.jun.yang.servlet;import java.io.File; import java.io.IOException; import java.util.UUID; 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;@WebServlet("/Upload") @MultipartConfig //必須使用此注解，標志此servlet 支持文件上傳 public class Upload extends HttpServlet {private static final long serialVersionUID = 1L;public Upload() {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//設置請求編碼request.setCharacterEncoding("utf-8"); //(part)此類表示在multipart/form-dataPOST請求中收到的部分或表單項。// Part part = request.getPart("filename");//獲取上下文對象，再獲取某文件夾的位置String path = request.getServletContext().getRealPath("file");//獲得頭部信息String headName = part.getHeader("content-disposition");
　　　　 System.out.println(headName);//截取文件后綴名String end = headName.substring(headName.indexOf("."), headName.length()-1);//隨機生成一個文件名，并拼接完整路徑String filename = path +File.separator+UUID.randomUUID().toString()+end;System.out.println(filename);//將上傳的項目寫入磁盤的方便方法。 part.write(filename); }protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response);} }

part接口：http://docs.oracle.com/javaee/6/api/javax/servlet/http/Part.html

html代碼：文件上傳一定要將enctype的值改為：enctype="multipart/form-data"

<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>文件上傳</title> </head> <body><form action="Upload" method="post" enctype="multipart/form-data"><input type="file" name="filename"><br/><br/><input type="submit" value="上傳"></form> </body> </html>

請求頭信息：

效果：

下載：

package ni.jun.yang.servlet;import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream;import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;@WebServlet("/DownServlet") public class downServlet extends HttpServlet {private static final long serialVersionUID = 1L;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.獲取要下載的文件的絕對路徑String realPath = this.getServletContext().getRealPath("111.txt");System.out.println(realPath);//2.獲取要下載的文件名String fileName = realPath.substring(realPath.lastIndexOf(File.separator)+1);String userAgent = request.getHeader("User-Agent");//針對IE或者以IE為內核的瀏覽器：if (userAgent.contains("MSIE")||userAgent.contains("Trident")) {fileName = java.net.URLEncoder.encode(fileName, "UTF-8");} else {//非IE瀏覽器的處理：fileName = new String(fileName.getBytes("UTF-8"),"ISO-8859-1");}//3.設置content-disposition響應頭控制瀏覽器以下載的方式打開文件response.setHeader("content-disposition","attachment;filename="+fileName);//4.獲取要下載的文件輸入流InputStream in = new FileInputStream(realPath);int len = 0;//5.創建書緩沖區byte[] buffer = new byte[1024];//6.通過response對象獲取OutputStream輸出流對象OutputStream os = response.getOutputStream();//7.將FileInputStream流對象寫入到buffer緩沖區while((len=in.read(buffer))>0){os.write(buffer,0,len);}//8.關閉流 in.close();os.close();}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}}

轉載于:https://www.cnblogs.com/nijunyang/p/7346992.html

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