javaweb实现文件上传与下载功能

 
 




 

 

 
上传者
 

 
 

 
上传文件
 

 
 

 
 

 
 
 

package cn.itcast.fileupload;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.List;
import java.util.UUID;
/**
 * Created by lc on 2018/8/24.
 */
@WebServlet(name = "UploadServlet",urlPatterns = "/UploadServlet")
public class UploadSevlet extends HttpServlet {
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doGet(request,response);
 }
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 try{
 response.setContentType("text/html;charset=utf-8");
// 创建DiskFileItemFactory工厂对象
 DiskFileItemFactory factory=new DiskFileItemFactory();
// 设置文件缓存目录，如果该文件夹不存在则创建一个
 File f=new File("S:\\TempFolder");
 if (!f.exists()){
 f.mkdirs();
 }
 factory.setRepository(f);
// 创建ServletFileUpload对象
 ServletFileUpload fileUpload=new ServletFileUpload(factory);
// 设置字符编码
 fileUpload.setHeaderEncoding("utf-8");
// 解析request，将form表单的各个字段封装为FileItem对象
 List fileItems = fileUpload.parseRequest(request);
// 获取字符流
 PrintWriter writer=response.getWriter();
// 遍历List集合
 for (FileItem fileItem:fileItems) {
// 判断是否为普通字段
 if (fileItem.isFormField()){
// 获取字段名称
 String name = fileItem.getFieldName();
 if(name.equals("name")){
// 如果字段值不为空
 if (!fileItem.getString().equals("")){
 String value=fileItem.getString("utf-8");
 writer.print("上传者："+value+"
");
 }
 }
 }
 else {
 //获取上传的文件名
 String filename=fileItem.getName();
// 处理上传文件
 if(filename!=null&&filename!=""){
 writer.print("上传的文件名称是："+filename+"
");
// 保持文件名唯一
 filename= UUID.randomUUID().toString()+"_"+filename;
 String webpath="/upload/";
// 创建文件路径
 String filepath=getServletContext().getRealPath(webpath+filename);
 //创建File对象
 File file=new File(filepath);
 //创建文件夹
 file.getParentFile().mkdirs();
 //创建文件
 file.createNewFile();
 //获取上传文件流
 InputStream in=fileItem.getInputStream();
// 使用 FileOutputStream打开服务器端的上传文件
 FileOutputStream out=new FileOutputStream(file);
// 流的对拷
 byte[] bytes=new byte[1024];//每次读取一个字节
 int len;
// 开始读取上传文件的字节，并将其输出到服务器端的上传文件输出流中
 while ((len=in.read(bytes))>0)
 out.write(bytes,0,len);
 in.close();
 out.close();
 fileItem.delete();
 writer.print("文件上传成功！");
 }
 }
 
 
 }
 }catch (Exception e){
 throw new RuntimeException(e);
 }
 }
}

 
 


文件下载

package cn.itcast.fileupload;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
 * Created by lc on 2018/8/24.
 */
@WebServlet(name = "DownloadServlet",urlPatterns = "/Download")
public class DownloadServlet extends HttpServlet {
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doGet(request,response);
 }
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 response.setContentType("text/html;charset=utf-8");
 //获取文件名
 String filename = request.getParameter("filename");
 //文件所在的文件夹
 String folder="/download/";
 //通知浏览器以下载的方式打开
 response.addHeader("Content-Type","application/octet-stream");
 response.addHeader("Content-Disposition","attachment;filename="+filename);
 //通过文件输入流读取文件
 InputStream in=getServletContext().getResourceAsStream(folder+filename);
 OutputStream out=response.getOutputStream();
 byte[] bytes=new byte[1024];
 int len=0;
 while ((len=in.read(bytes))!=-1){
 out.write(bytes,0,len);
 }
 }
}