文件下載

原創 chitry_ 2018-08-27 19:58


2014年9月8日 16:43:59




package cn.itcast.web.controller;
 
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;
//顯示所有上傳的文件，封裝到域對象中，交給jsp去顯示
public class ShowAllFilesServlet extends HttpServlet {
 
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		Map<String, String> map = new HashMap<String, String>();//key：UUID文件名；value：老文件名
		//得到存儲文件的根目錄
		String storePath = getServletContext().getRealPath("/WEB-INF/files");
		//遞歸遍歷其中文件
		File file = new File(storePath);
		treeWalk(file,map);
		//交給JSP去顯示：如何封裝數據.用Map封裝。key：UUID文件名；value：老文件名
		request.setAttribute("map", map);
		request.getRequestDispatcher("/listFiles.jsp").forward(request, response);
	}
	//遍歷/WEB-INF/files所有文件，把文件名放到map中
	private void treeWalk(File file, Map<String, String> map) {
		if(file.isFile()){
			//是文件
			String uuidName = file.getName();//  UUID_a_a.txt//真實文件名
			String oldName = uuidName.substring(uuidName.indexOf("_")+1);
			map.put(uuidName, oldName);
		}else{
			//是一個目錄
			File[] fs = file.listFiles();
			for(File f:fs){
				treeWalk(f,map);
			}
		}
	}
 
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
 
		doGet(request, response);
	}
 
}




package cn.itcast.web.controller;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//文件的下載
public class DownloadServlet extends HttpServlet {
 
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		OutputStream out = response.getOutputStream();
		
		String filename = request.getParameter("filename");//get請求方式
		filename = new String(filename.getBytes("ISO-8859-1"),"UTF-8");//中文編碼
		
		//截取老文件名
		String oldFileName = filename.split("_")[1];
		//得到存儲路徑
		String storePath = getServletContext().getRealPath("/WEB-INF/files");
		//得到文件的全部路徑
		String filePath = makeStorePath(storePath, filename)+"\\"+filename;
		
		//判斷文件是否存在
		File file = new File(filePath);
		if(!file.exists()){
			out.write("對比起！你要下載的文件可能已經不存在了".getBytes("UTF-8"));
			return;
		}
		
		InputStream in = new FileInputStream(file);
		//通知客戶端以下載的方式打開
		response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(oldFileName, "UTF-8"));
		
		byte[] b = new byte[1024];
		int len = -1;
		while((len=in.read(b))!=-1){
			out.write(b, 0, len);
		}
		in.close();
		out.write("下載成功".getBytes("UTF-8"));
	}
 
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
 
		doGet(request, response);
	}
	private String makeStorePath(String storePath, String fileName) {
		int hashCode = fileName.hashCode();
		int dir1 = hashCode & 0xf;// 0000~1111：整數0~15共16個
		int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整數0~15共16個
 
		String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
		File file = new File(path);
		if (!file.exists())
			file.mkdirs();
 
		return path;
	}
}





<%@ 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></title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
 
  </head>
  
  <body>
    <h1>本站有以下好圖片</h1>
    <c:forEach items="${map}" var="me">
    	<c:url value="/servlet/DownloadServlet" var="url">
    		<c:param name="filename" value="${me.key}"></c:param>
    	</c:url>
    	${me.value}  <a href="${url}">下載</a><br/>
    </c:forEach>
  </body>
</html>

2014年9月8日 16:43:59




package cn.itcast.web.controller;
 
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;
//顯示所有上傳的文件，封裝到域對象中，交給jsp去顯示
public class ShowAllFilesServlet extends HttpServlet {
 
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		Map<String, String> map = new HashMap<String, String>();//key：UUID文件名；value：老文件名
		//得到存儲文件的根目錄
		String storePath = getServletContext().getRealPath("/WEB-INF/files");
		//遞歸遍歷其中文件
		File file = new File(storePath);
		treeWalk(file,map);
		//交給JSP去顯示：如何封裝數據.用Map封裝。key：UUID文件名；value：老文件名
		request.setAttribute("map", map);
		request.getRequestDispatcher("/listFiles.jsp").forward(request, response);
	}
	//遍歷/WEB-INF/files所有文件，把文件名放到map中
	private void treeWalk(File file, Map<String, String> map) {
		if(file.isFile()){
			//是文件
			String uuidName = file.getName();//  UUID_a_a.txt//真實文件名
			String oldName = uuidName.substring(uuidName.indexOf("_")+1);
			map.put(uuidName, oldName);
		}else{
			//是一個目錄
			File[] fs = file.listFiles();
			for(File f:fs){
				treeWalk(f,map);
			}
		}
	}
 
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
 
		doGet(request, response);
	}
 
}




package cn.itcast.web.controller;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//文件的下載
public class DownloadServlet extends HttpServlet {
 
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		OutputStream out = response.getOutputStream();
		
		String filename = request.getParameter("filename");//get請求方式
		filename = new String(filename.getBytes("ISO-8859-1"),"UTF-8");//中文編碼
		
		//截取老文件名
		String oldFileName = filename.split("_")[1];
		//得到存儲路徑
		String storePath = getServletContext().getRealPath("/WEB-INF/files");
		//得到文件的全部路徑
		String filePath = makeStorePath(storePath, filename)+"\\"+filename;
		
		//判斷文件是否存在
		File file = new File(filePath);
		if(!file.exists()){
			out.write("對比起！你要下載的文件可能已經不存在了".getBytes("UTF-8"));
			return;
		}
		
		InputStream in = new FileInputStream(file);
		//通知客戶端以下載的方式打開
		response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(oldFileName, "UTF-8"));
		
		byte[] b = new byte[1024];
		int len = -1;
		while((len=in.read(b))!=-1){
			out.write(b, 0, len);
		}
		in.close();
		out.write("下載成功".getBytes("UTF-8"));
	}
 
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
 
		doGet(request, response);
	}
	private String makeStorePath(String storePath, String fileName) {
		int hashCode = fileName.hashCode();
		int dir1 = hashCode & 0xf;// 0000~1111：整數0~15共16個
		int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整數0~15共16個
 
		String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
		File file = new File(path);
		if (!file.exists())
			file.mkdirs();
 
		return path;
	}
}





<%@ 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></title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
 
  </head>
  
  <body>
    <h1>本站有以下好圖片</h1>
    <c:forEach items="${map}" var="me">
    	<c:url value="/servlet/DownloadServlet" var="url">
    		<c:param name="filename" value="${me.key}"></c:param>
    	</c:url>
    	${me.value}  <a href="${url}">下載</a><br/>
    </c:forEach>
  </body>
</html>

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