文件上传与下载详细解析与实现 - 黑马程序员技术交流社区

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'upload.jsp' starting page</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/servlet/UploadServlet3" <font color="Red">enctype="multipart/form-data" method="post"</font>>
上传用户：<input type="text" name="username"><br/>
上传文件1：<input type="file" name="file1"><br/>
上传文件2：<input type="file" name="file2"><br/>
<input type="submit" value="上传">
</form>
</body>
</html>

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package cn.itcast.web.servlet;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
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;
//处理上传数据
public class UploadServlet2 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try{
DiskFileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List<FileItem> list = upload.parseRequest(request);
for(FileItem item : list){
if(item.isFormField()){
//为普通输入项
String inputName = item.getFieldName();
String inputValue = item.getString();
System.out.println(inputName + "=" + inputValue);
}else{
//代表当前处理的item里面封装的是上传文件
//C:\Documents and Settings\ThinkPad\桌面\a.txt a.txt
String filename = item.getName().substring(item.getName().lastIndexOf("\\")+1);
InputStream in = item.getInputStream();
int len = 0;
byte buffer[] = new byte[1024];
FileOutputStream out = new FileOutputStream("c:\\" + filename);
while((len=in.read(buffer))>0){
out.write(buffer, 0, len);
}
in.close();
out.close();
}
}
}catch (Exception e) {
throw new RuntimeException(e);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}

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package cn.itcast.web.servlet;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
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.FileUploadBase;
import org.apache.commons.fileupload.ProgressListener;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet3 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
List types = Arrays.asList("jpg","gif","avi","txt");
try{
DiskFileItemFactory factory = new DiskFileItemFactory(); //10k
factory.setSizeThreshold(1024*1024);
factory.setRepository(new File(this.getServletContext().getRealPath("/temp")));
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setProgressListener(new ProgressListener(){
public void update(long pBytesRead, long pContentLength, int pItems) {
System.out.println("当前已解析：" + pBytesRead);
}
});
upload.setFileSizeMax(1024*1024*5);
if(!upload.isMultipartContent(request)){
//按照传统方式获取表单数据
request.getParameter("username");
return;
}
upload.setHeaderEncoding("UTF-8");
List<FileItem> list = upload.parseRequest(request);
for(FileItem item : list){
if(item.isFormField()){
//为普通输入项
String inputName = item.getFieldName();
String inputValue = item.getString("UTF-8");
//inputValue = new String(inputValue.getBytes("iso8859-1"),"UTF-8");
System.out.println(inputName + "=" + inputValue);
}else{
String filename = item.getName().substring(item.getName().lastIndexOf("\\")+1); //""
if(filename==null || filename.trim().equals("")){
continue;
}
/*String ext = filename.substring(filename.lastIndexOf(".")+1);
if(!types.contains(ext)){
request.setAttribute("message", "本系统不支持" + ext + "这种类型");
request.getRequestDispatcher("/message.jsp").forward(request, response);
return;
}*/
InputStream in = item.getInputStream();
int len = 0;
byte buffer[] = new byte[1024];
String saveFileName = generateFileName(filename);
String savepath = generateSavePath(this.getServletContext().getRealPath("/WEB-INF/upload"),saveFileName);
FileOutputStream out = new FileOutputStream(savepath + File.separator + saveFileName);
while((len=in.read(buffer))>0){
out.write(buffer, 0, len);
}
in.close();
out.close();
item.delete(); //删除临时文件
}
}
}catch (FileUploadBase.FileSizeLimitExceededException e) {
request.setAttribute("message", "文件大小不能超过5m");
request.getRequestDispatcher("/message.jsp").forward(request, response);
return;
}catch (Exception e) {
throw new RuntimeException(e);
}
request.setAttribute("message", "上传成功！！");
request.getRequestDispatcher("/message.jsp").forward(request, response);
}
//
public String generateSavePath(String path,String filename){
int hashcode = filename.hashCode(); //121221
int dir1 = hashcode&15;
int dir2 = (hashcode>>4)&0xf;
String savepath = path + File.separator + dir1 + File.separator + dir2;
File file = new File(savepath);
if(!file.exists()){
file.mkdirs();
}
return savepath;
}
public String generateFileName(String filename){
//83434-83u483-934934
return UUID.randomUUID().toString() + "_" + filename;
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}

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package cn.itcast.web.servlet;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//列出网站所有文件
public class ListFileServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = this.getServletContext().getRealPath("/WEB-INF/upload");
Map map = new HashMap();
listfile(new File(path),map);
request.setAttribute("map", map);
request.getRequestDispatcher("/listfile.jsp").forward(request, response);
}
//如何保存迭归出来的资源
public void listfile(File file,Map map){
if(!file.isFile()){
File children[] = file.listFiles();
for(File f : children){
listfile(f,map);
}
}else{
String filename = file.getName().substring(file.getName().indexOf("_")+1); //8347824284-343-343_a_b.txt
map.put(file.getName(),filename); //<a href="/servlet?filename=文件在服务器的名称">文件的原始文件名</a>
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}

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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>文件列表</title>
</head>
<body>
下载文件有：<br/>
<c:forEach var="entry" items="${requestScope.map}">
<c:url var="url" value="/servlet/DownLoadServlet">
<c:param name="filename" value="${entry.key}"></c:param>
</c:url>
${entry.value } <a href="${url }">下载</a><br/>
</c:forEach>
</body>
</html>

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