javaweb基於spring MVC的上傳下載例項(下)
阿新 • • 發佈：2019-02-07
檔案下載
要將Web應用系統中的檔案資源提供給使用者進行下載，首先我們要有一個頁面列出上傳檔案目錄下的所有檔案，當用戶點選檔案下載超連結時就進行下載操作，編寫一個ListFileServlet，用於列出Web應用系統中所有下載檔案。
1.1 搭建前臺頁面
download.html程式碼如下:
<!DOCTYPE HTML>
<html>
<head> <title>下載檔案顯示頁面</title></head>
<body>
<div id="fileName"></div> 對download.html新增js:
<script >
<!-- 初始化載入download()函式 -->
$(function(){
download();
});
function download(){
$.ajax({
url: 'cloud/load/download',
type: 'POST',
dataType:'JSON',
cache: false,
processData: false,
contentType: false 說明:
在spring mvc框架下,通過spring註解,這裡的ajax的url指向的是UploadAndDownloadController的download()方法
1.2 controller
UploadAndDownloadController.Java程式碼如下:
package com.cloud.web.controller;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.Resource;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import com.cloud.web.service.FileLoadService;
@Controller
@RequestMapping("/load")
public class UploadAndDownloadController {
@Resource
public FileLoadService fileLoadService;
/**
* 顯示要下載的檔案
* @param request
* @param response
* @param model
* @return
* @throws ServletException
* @throws IOException
*/
@RequestMapping(value = "/download", method = RequestMethod.POST)
@ResponseBody
public Map<String,String> download(HttpServletRequest request, HttpServletResponse response, ModelMap model) throws ServletException, IOException{
Map<String,String> map = fileLoadService.doGet(request, response);
return map;
}
/**
* 檔案下載到本地
* @param request
* @param response
* @param model
* @throws ServletException
* @throws IOException
*/
@RequestMapping(value = "/downloadFile", method = RequestMethod.GET)
@ResponseBody
public void downloadFile(HttpServletRequest request, HttpServletResponse response, ModelMap model) throws ServletException, IOException{
String filename =request.getParameter("fileName");
fileLoadService.doGetFile(request, response ,filename);
}
}
1.3 service介面
FileLoadService程式如下:
package com.cloud.web.service;
import java.io.File;
import java.io.IOException;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public interface FileLoadService {
Map<String,String> doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException;
void listfile(File file,Map<String,String> map);
void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException;
void doGetFile(HttpServletRequest request, HttpServletResponse response,String filename) throws ServletException, IOException;
}1.4 service的實現類
FileLoadServiceImpl.java程式如下:
package com.cloud.web.service.impl;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Service;
import com.cloud.web.service.FileLoadService;
@Service
public class FileLoadServiceImpl implements FileLoadService{
/**
* 待下載檔案的顯示
*/
@Override
public Map<String,String> doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
//獲取上傳檔案的目錄
String uploadFilePath = "/D:/Download/";
//儲存要下載的檔名
Map<String,String> fileNameMap = new HashMap<String,String>();
//遞迴遍歷uploadFilePath目錄下的所有檔案和目錄，將檔案的檔名儲存到map集合中
listfile(new File(uploadFilePath),fileNameMap);//File既可以代表一個檔案也可以代表一個目錄
//將Map集合返回頁面
return fileNameMap;
}
public void listfile(File file,Map<String,String> map){
//如果file代表的不是一個檔案，而是一個目錄
if(!file.isFile()){
//列出該目錄下的所有檔案和目錄
File files[] = file.listFiles();
//遍歷files[]陣列
for(File f : files){
//遞迴
listfile(f,map);
}
}else{
String realName = file.getName().substring(file.getName().indexOf("_")+1);
//file.getName()得到的是檔案的原始名稱，這個名稱是唯一的，因此可以作為key，realName是處理過後的名稱，有可能會重複
map.put(file.getName(), realName);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
/**
* 將顯示的檔案下載到本地
*/
@Override
public void doGetFile(HttpServletRequest request, HttpServletResponse response,String filename) throws ServletException,IOException {
//得到要下載的檔名
String fileName = filename;
//解決亂碼問題
fileName = new String(fileName.getBytes("iso8859-1"),"UTF-8");
String fileSaveRootPath="/D:/Download";
//檔案路徑
File file = new File(fileSaveRootPath + "/" + fileName);
//如果檔案不存在
if(!file.exists()){
request.setAttribute("message", "您要下載的資源已被刪除！！");
return;
}
//處理檔名
String realname = fileName.substring(fileName.indexOf("_")+1);
//設定響應頭，控制瀏覽器下載該檔案
response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(realname, "UTF-8"));
InputStream fis = new BufferedInputStream(new FileInputStream(fileSaveRootPath + "\\" + fileName));
byte[] buffer = new byte[fis.available()];
fis.read(buffer); //讀取檔案流
fis.close();//關閉檔案流
response.reset();//重置結果集
response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(realname, "UTF-8"));
response.addHeader("Content-Length", "" + file.length()); //返回頭 檔案大小
response.setContentType("application/octet-stream"); //設定資料種類
///獲取返回體輸出權
OutputStream os = new BufferedOutputStream(response.getOutputStream());
os.write(buffer); // 輸出檔案
os.flush();
os.close();
}
public void doPostFile(HttpServletRequest request, HttpServletResponse response,String filename)throws ServletException, IOException {
doGetFile(request, response,filename);
}
}以上 檔案下載完成~