java 上传下载demo_Java Servlet简单实例,文件上传下载demo

packagecom.servletdemo;importjava.io.File;importjava.io.FileOutputStream;importjava.io.IOException;importjava.io.InputStream;importjava.io.OutputStream;importjava.io.PrintWriter;importjava.text.DateFormat;importjava.util.Date;importjava.util.List;importjava.util.UUID;importjavax.servlet.ServletException;importjavax.servlet.annotation.WebServlet;importjavax.servlet.http.HttpServlet;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse;importorg.apache.commons.fileupload.FileItem;importorg.apache.commons.fileupload.FileUploadException;importorg.apache.commons.fileupload.ProgressListener;importorg.apache.commons.fileupload.disk.DiskFileItemFactory;importorg.apache.commons.fileupload.servlet.ServletFileUpload;/*** Servlet implementation class UploadServlet*/@WebServlet("/servlet/UploadServlet")public class UploadServlet extendsHttpServlet {private static final long serialVersionUID = 1L;/***@seeHttpServlet#HttpServlet()*/

publicUploadServlet() {super();//TODO Auto-generated constructor stub

}/***@seeHttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throwsServletException, IOException {//TODO Auto-generated method stub//设置编码

request.setCharacterEncoding("UTF-8");

response.setContentType("text/html;charset=UTF-8");

PrintWriter pw=response.getWriter();try{//设置系统环境

DiskFileItemFactory factory = newDiskFileItemFactory();//文件存储的路径

String storePath = getServletContext().getRealPath("/WEB-INF/files");//判断传输方式 form enctype=multipart/form-data

boolean isMultipart =ServletFileUpload.isMultipartContent(request);if(!isMultipart)

{

pw.write("传输方式有错误！");return;

}

ServletFileUpload upload= newServletFileUpload(factory);

upload.setFileSizeMax(4*1024*1024);//设置单个文件大小不能超过4M

upload.setSizeMax(4*1024*1024);//设置总文件上传大小不能超过6M//监听上传进度

upload.setProgressListener(newProgressListener() {//pBytesRead：当前以读取到的字节数//pContentLength：文件的长度//pItems:第几项

public void update(long pBytesRead, longpContentLength,intpItems) {

System.out.println("已读去文件字节 :"+pBytesRead+" 文件总长度："+pContentLength+" 第"+pItems+"项");

}

});//解析

List items =upload.parseRequest(request);for(FileItem item: items)

{if(item.isFormField())//普通字段，表单提交过来的

{

String name=item.getFieldName();

String value= item.getString("UTF-8");

System.out.println(name+"=="+value);

}else{//String mimeType = item.getContentType(); 获取上传文件类型//if(mimeType.startsWith("image")){

InputStream in =item.getInputStream();

String fileName=item.getName();if(fileName==null || "".equals(fileName.trim()))

{continue;

}

fileName= fileName.substring(fileName.lastIndexOf("\")+1);

fileName= UUID.randomUUID()+"_"+fileName;//按日期来建文件夹

String newStorePath =makeStorePath(storePath);

String storeFile= newStorePath+"\"+fileName;

OutputStream out= newFileOutputStream(storeFile);byte[] b = new byte[1024];int len = -1;while((len = in.read(b))!=-1)

{

out.write(b,0,len);

}

in.close();

out.close();

item.delete();//删除临时文件

}

}//}

}catch(org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException e){//单个文件超出异常

pw.write("单个文件不能超过4M");

}catch(org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e){//总文件超出异常

pw.write("总文件不能超过6M");

}catch(FileUploadException e) {

e.printStackTrace();

}

}/***@seeHttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throwsServletException, IOException {//TODO Auto-generated method stub

doGet(request, response);

}privateString makeStorePath(String storePath) {

Date date= newDate();

DateFormat df=DateFormat.getDateInstance(DateFormat.MEDIUM);

String s=df.format(date);

String path= storePath+"\"+s;

File file= newFile(path);if(!file.exists())

{

file.mkdirs();//创建多级目录，mkdir只创建一级目录

}returnpath;

}privateString makeStorePath2(String storePath, String fileName) {int hashCode =fileName.hashCode();int dir1 = hashCode & 0xf;//0000~1111：整数0~15共16个

int dir2 = (hashCode & 0xf0) >> 4;//0000~1111：整数0~15共16个

String path= storePath + "\" + dir1 + "\" + dir2; //WEB-INF/files/1/12

File file = newFile(path);if (!file.exists())

file.mkdirs();returnpath;

}

}