java如何实现文件下载|Java 下载文件的方法怎么写

❶ java response.getOutputStream()实现多个文件下载,已经拿到两个字节数组的list,下载的时候如何同时下载

可以一个接口传多个文李模件,每个文件中间用特定符号拆分,也可以写一渣扰知个接口前端多次调用,将请求头的文件格式改为blob,前端获取文件流后如消调用下载

❷ 怎样编一个能实现文件下载功能的JAVA程序

java实现文件下载一、采用RequestDispatcher的方式进行1、web.xml文件中增加<mime-mapping> <extension>doc</extension> <mime-type>application/vnd.ms-word</mime-type></mime-mapping>2、程序如下: <%@page language="java" import="java.net.*" pageEncoding="gb2312"%><%response.setContentType("application/x-download");//设置为下载application/x-download String filenamedownload = "/系统解决方案.doc";//即将下载的文件的相对路径 String filenamedisplay = "系统解决方案.doc";//下载文件时显示的文件保存名称 filenamedisplay = URLEncoder.encode(filenamedisplay,"UTF-8"); response.addHeader("Content-Disposition","attachment;filename=" + filenamedisplay); try { RequestDispatcher dispatcher = application.getRequestDispatcher(filenamedownload); if(dispatcher != null) { dispatcher.forward(request,response); } response.flushBuffer(); } catch(Exception e) { e.printStackTrace(); } finally { }%>二、采用文件流输出的方式下载1、web.xml文件中增加<mime-mapping> <extension>doc</extension> <mime-type>application/vnd.ms-word</mime-type></mime-mapping>2、程序如下: <%@page language="java" contentType="application/x-msdownload" import="java.io.*,java.net.*" pageEncoding="gb2312"%><%//关于文件下载时采用文件流输出的方式处理: //加上response.reset(),并且所有的%>后面不要换行,包括最后一个; //因为Application Server在处理编译jsp时对于%>和<%之间的内容一般是原样输出,而且默认是PrintWriter, //而你却要进行流输出:ServletOutputStream,这样做相当于试图在Servlet中使用两种输出机制, //就会发生:getOutputStream() has already been called for this response的错误 //详细请见《More Java Pitfill》一书的第二部分 Web层Item 33:试图在Servlet中使用两种输出机制 270 //而且如果有换行,对于文本文件没有什么问题,但是对于其它格式,比如AutoCAD、Word、Excel等文件 //下载下来的文件中就会多出一些换行符0x0d和0x0a,这样可能导致某些格式的文件无法打开,有些也可以正常打开。 response.reset();//可以加也可以不加 response.setContentType("application/x-download");//设置为下载application/x-download // /../../退WEB-INF/classes两级到应用的根目录下去,注意Tomcat与WebLogic下面这一句得到的路径不同,WebLogic中路径最后没有/ System.out.println(this.getClass().getClassLoader().getResource("/").getPath()); String filenamedownload = this.getClass().getClassLoader().getResource("/").getPath() + "/../../系统解决方案.doc"; String filenamedisplay = "系统解决方案.doc";//系统解决方案.txt filenamedisplay = URLEncoder.encode(filenamedisplay,"UTF-8"); response.addHeader("Content-Disposition","attachment;filename=" + filenamedisplay); OutputStream output = null; FileInputStream fis = null; try { output = response.getOutputStream(); fis = new FileInputStream(filenamedownload); byte[] b = new byte[1024]; int i = 0; while((i = fis.read(b)) > 0) { output.write(b, 0, i); } output.flush(); } catch(Exception e) { System.out.println("Error!"); e.printStackTrace(); } finally { if(fis != null) {

❸ 怎样通过java实现服务器上文件下载

用HttpClient(commons httpclient)包,模拟一个Get请求,发送到网址172.16.30.230/文件地址。这个文件地址不能是E/Map/123.txt,必须是暴露在服务专器属中的应用里的。就像你写的应用里的一个jsp页面的目录。成功发送get请求后,就会得到response,里面有流。就是你下载的文件,然后可以通过FileOutputStream,指定你输出目录,写到磁盘上。

❹ Javaweb中的文件下载实现

需要在响复应头部加上一制些标示,告诉浏览器这个是文件下载。如果你用了框架比如struts,需要加如下配置<result name="success" type="stream"> <param name="contentType">application/octet-stream;charset=ISO8859-1</param> <param name="inputName">fileStream</param> <param name="contentDisposition">attachment;filename="${fileName}"</param> <param name="bufferSize">2048</param> </result>如果没有用框架,就手动在返回对象添加这些contentType

❺ Java 下载文件的方法怎么写

参考下面public HttpServletResponse download(String path, HttpServletResponse response) {try {// path是指欲下载的文件的路径。File file = new File(path);// 取得文件名。String filename = file.getName();// 取得文件的后缀名。String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();// 以流的形式下载文件。InputStream fis = new BufferedInputStream(new FileInputStream(path));byte[] buffer = new byte[fis.available()];fis.read(buffer);fis.close();// 清空responseresponse.reset();// 设置response的Headerresponse.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));response.addHeader("Content-Length", "" + file.length());OutputStream toClient = new BufferedOutputStream(response.getOutputStream());response.setContentType("application/octet-stream");toClient.write(buffer);toClient.flush();toClient.close();} catch (IOException ex) {ex.printStackTrace();}return response;}// 下载本地文件public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {String fileName = "Operator.doc".toString(); // 文件的默认保存名// 读到流中InputStream inStream = new FileInputStream("c:/Operator.doc");// 文件的存放路径// 设置输出的格式response.reset();response.setContentType("bin");response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");// 循环取出流中的数据byte[] b = new byte[100];int len;try {while ((len = inStream.read(b)) > 0)response.getOutputStream().write(b, 0, len);inStream.close();} catch (IOException e) {e.printStackTrace();}}// 下载网络文件public void downloadNet(HttpServletResponse response) throws MalformedURLException {int bytesum = 0;int byteread = 0;URL url = new URL("windine.blogdriver.com/logo.gif");try {URLConnection conn = url.openConnection();InputStream inStream = conn.getInputStream();FileOutputStream fs = new FileOutputStream("c:/abc.gif");byte[] buffer = new byte[1204];int length;while ((byteread = inStream.read(buffer)) != -1) {bytesum += byteread;System.out.println(bytesum);fs.write(buffer, 0, byteread);}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}//支持在线打开文件的一种方式public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {File f = new File(filePath);if (!f.exists()) {response.sendError(404, "File not found!");return;}BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));byte[] buf = new byte[1024];int len = 0;response.reset(); // 非常重要if (isOnLine) { // 在线打开方式URL u = new URL("file:///" + filePath);response.setContentType(u.openConnection().getContentType());response.setHeader("Content-Disposition", "inline; filename=" + f.getName());// 文件名应该编码成UTF-8} else { // 纯下载方式response.setContentType("application/x-msdownload");response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());}OutputStream out = response.getOutputStream();while ((len = br.read(buf)) > 0)out.write(buf, 0, len);br.close();out.close();}

❻ java 关于创建txt文件并下载的实现方法

看不明白,下面这一行是伪代码么?

FileUtil.writeline(eeFile,errorMsgList,constans.UTF8);

这一行里eeFile是什么?为何前面叫errFile?

如果不行的话,你干脆就把errorMsgList写入当前网页不行么?

response.getWriter().print(errorMsgList);

❼ 有没大神教教我java怎么实现文件下载的,不要超链接那种,要有action求jsp和action

<a href="control/downFile.do?pistrPath=' + rec.get('path') + '">'请求到后台,把文件地址传到慧仔后台 /** * 下载文件 * @param pistrPath * @param piobjResponse * @throws MalformedURLException */前键汪 public void downloadNet(String pistrPath, HttpServletResponse piobjResponse) throws MalformedURLException { // 下载网络文件亮喊 int iByte = 0; System.getProperties(); try { URL objurl = new URL(pistrPath); System.out.println(pistrPath); URLEncoder.encode(objurl.toString(), SengisConstant.STR_CN_ENCODE); URLConnection objConn = objurl.openConnection(); InputStream objInputStream = objConn.getInputStream(); OutputStream objOutStream = piobjResponse.getOutputStream(); byte[] arrByte = new byte[1204]; while ((iByte = objInputStream.read(arrByte)) != -1) { objOutStream.write(arrByte, 0, iByte); } objOutStream.flush(); objOutStream.close(); objInputStream.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }

❽ JAVA文件下载如何实现

下载就很简单了把你要下载的文件做成超级链接,可以不用任何组件比如说下载一个word文档<a href="名称.doc">名称.doc</a>路径你自己写

❾ 通过java实现文件下载

在jsp/servlet中断点/多线程下载文件<%@ page import="java.io.File" %><%@ page import="java.io.IOException" %><%@ page import="java.io.OutputStream" %><%@ page import="java.io.RandomAccessFile" %><%! public void downloadFile(HttpServletRequest request, HttpServletResponse response, File file) throws IOException { RandomAccessFile raf = new RandomAccessFile(file, "r"); java.io.FileInputStream fis = new java.io.FileInputStream(raf.getFD()); response.setHeader("Server", "www.trydone.com"); response.setHeader("Accept-Ranges", "bytes"); long pos = 0; long len; len = raf.length(); if (request.getHeader("Range") != null) { response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); pos = Long.parseLong(request.getHeader("Range") .replaceAll("bytes=", "") .replaceAll("-", "") ); } response.setHeader("Content-Length", Long.toString(len – pos)); if (pos != 0) { response.setHeader("Content-Range", new StringBuffer() .append("bytes ") .append(pos) .append("-") .append(Long.toString(len – 1)) .append("/") .append(len) .toString() ); } response.setContentType("application/octet-stream"); response.setHeader("Content-Disposition", new StringBuffer() .append("attachment;filename=\"") .append(file.getName()) .append("\"").toString()); raf.seek(pos); byte[] b = new byte[2048]; int i; OutputStream outs = response.getOutputStream(); while ((i = raf.read(b)) != -1) { outs.write(b, 0, i); } raf.close(); fis.close(); }%><% String filePath = request.getParameter("file"); filePath = application.getRealPath(filePath); File file = new File(filePath); downloadFile(request, response, file);%>是否可以解决您的问题?

❿ 用java实现文件的上传与下载

1.下载简单,无非是把服务器上的文件或者数据库中的BLob(或其他二进制型),用流读出来,然后写到客户端即可,要注意 ContentType。2.上传,可以用Apache Commons Upload等开源工具,或者自己写:form要用enctype="multipart/form-data"然后服务器端也是用IO把客户端提交的文件流读入,然后写到服务器的文件系统或者数据库里。不同的数据库对Lob字段操作可能有所不同,建议用Hibernate,JPA等成熟的ORM框架,可以不考虑数据库细节。


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