java文件代码下载 下载文件 java

Java中文件下载该怎么写代码求高手指导

if (upfile.exists()) {

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bytes = FileUtils.readFileToByteArray(upfile);

response.setContentType("application/x-download");

String agent = request.getHeader("USER-AGENT");//用户代理

// 防止中文文件名乱码

if (null != agent -1 != agent.indexOf("MSIE")) {

String codedfilename = StringUtils.replace(URLEncoder.encode(fileName, "UTF-8"), "+", "%20");

response.setHeader("Content-Disposition", "attachment;filename=" + codedfilename);

} else if (null != agent -1 != agent.indexOf("Mozilla")) {

String codedfilename = MimeUtility.encodeText(fileName, "UTF-8", "B");

response.setHeader("Content-Disposition", "attachment;filename=" + codedfilename);

} else {

response.setHeader("Content-Disposition", "attachment;filename=" + fileName);

}

response.setContentLength(bytes.length);

response.getOutputStream().write(bytes);

}

Java文件下载怎么实现的

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

import java.io.File;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.io.RandomAccessFile;

import java.net.HttpURLConnection;

import java.net.ProtocolException;

import java.net.URI;

import java.net.URL;

import java.util.Random;

/**

*

* 实现了下载的功能*/

public class SimpleTh {

public static void main(String[] args){

// TODO Auto-generated method stub

//String path = "倩女幽魂.mp3";//MP3下载的地址

String path ="";

try {

new SimpleTh().download(path, 3); //对象调用下载的方法

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

public static String getFilename(String path){//获得文件的名字

return path.substring(path.lastIndexOf('/')+1);

}

public void download(String path,int threadsize) throws Exception//下载的方法

{//参数 下载地址，线程数量

URL url = new URL(path);

HttpURLConnection conn = (HttpURLConnection)url.openConnection();//获取HttpURLConnection对象

conn.setRequestMethod("GET");//设置请求格式，这里是GET格式

conn.setReadTimeout(5*1000);//

int filelength = conn.getContentLength();//获取要下载文件的长度

String filename = getFilename(path);

File saveFile = new File(filename);

RandomAccessFile accessFile = new RandomAccessFile(saveFile, "rwd");

accessFile.setLength(filelength);

accessFile.close();

int block = filelength%threadsize ==0?filelength/threadsize:filelength/threadsize+1;

for(int threadid = 0;threadid=threadsize;threadid++){

new DownloadThread(url,saveFile,block,threadid).start();

}

}

private final class DownloadThread extends Thread{

private URL url;

private File saveFile;

private int block;//每条线程下载的长度

private int threadid;//线程id

public DownloadThread(URL url,File saveFile,int block,int threadid){

this.url = url;

this.saveFile= saveFile;

this.block = block;

this.threadid = threadid;

}

@Override

public void run() {

//计算开始位置的公式：线程id*每条线程下载的数据长度=？

//计算结束位置的公式：（线程id+1）*每条线程下载数据长度-1=？

int startposition = threadid*block;

int endposition = (threadid+1)*block-1;

try {

try {

RandomAccessFile accessFile = new RandomAccessFile(saveFile, "rwd");

accessFile.seek(startposition);//设置从什么位置写入数据

HttpURLConnection conn = (HttpURLConnection)url.openConnection();

conn.setRequestMethod("GET");

conn.setReadTimeout(5*1000);

conn.setRequestProperty("Range","bytes= "+startposition+"-"+endposition);

InputStream inStream = conn.getInputStream();

byte[]buffer = new byte[1024];

int len = 0;

while((len = inStream.read(buffer))!=-1){

accessFile.write(buffer, 0, len);

}

inStream.close();

accessFile.close();

System.out.println("线程id："+threadid+"下载完成");

} catch (FileNotFoundException e) {

e.printStackTrace();

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

java下载服务器上的文件到客户端

java编程方法下载服务器上的文件到本地客服端，代码如下：

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileOutputStream;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.net.URL;

import java.net.URLConnection;

public class DownLoad {   

public static void downloadFile(URL theURL, String filePath) throws IOException {  

File dirFile = new File(filePath);

if(!dirFile.exists()){ 

//文件路径不存在时，自动创建目录

dirFile.mkdir();

}

//从服务器上获取图片并保存

URLConnection connection = theURL.openConnection();

InputStream in = connection.getInputStream();  

FileOutputStream os = new FileOutputStream(filePath+"\\123.png"); 

byte[] buffer = new byte[4 * 1024];  

int read;  

while ((read = in.read(buffer))  0) {  

os.write(buffer, 0, read);  

}  

os.close();  

in.close();

}   

public static void main(String[] args) { 

//下面添加服务器的IP地址和端口，以及要下载的文件路径

String urlPath = "http://服务器IP地址:端口/image/123.png"; 

//下面代码是下载到本地的位置

String filePath = "d:\\excel"; 

URL url = new URL(urlPath); 

try { 

downloadFile(url,filePath); 

} catch (IOException e) { 

e.printStackTrace(); 

} 

}   

}

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", ""); 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？

使用java代码下载word文件

我同事在做项目的时候也遇到这个问题，应该是插件本身生成的docx文件是xml格式的，有些版本的word打开是会有提示，如果没有必要最好生成doc格式的word

java 代码实现下载.doc文件

%@ page contentType="text/html; charset=gb2312" %

%@ page import="java.io.*"%

%!

public String toUtf8String(String s)

{

StringBuffer sb = new StringBuffer();

for (int i=0;is.length();i++) {

char c = s.charAt(i);

if (c = 0 c = 255) {

sb.append(c);

} else {

byte[] b;

try {

b = Character.toString(c).getBytes("utf-8");

} catch (Exception ex) {

System.out.println(ex);

b = new byte[0];

}

for (int j = 0; j b.length; j++) {

int k = b[j];

if (k 0) k += 256;

sb.append("%" + Integer.toHexString(k).

toUpperCase());

}

}

}

return sb.toString();

}

%

%

String filename=new String(request.getParameter("filename").getBytes("ISO8859-1"),"GBK");

String dirName="D:/我.doc";

java.io.File ff=null;

String dd=dirName+System.getProperties().getProperty("file.separator")+filename;

try{

ff=new java.io.File(dd);

}

catch(Exception e){

System.out.println(e.getMessage());

e.printStackTrace();

}

if (ff!=nullff.exists()ff.isFile())

{

long filelength = ff.length();

InputStream inStream=new FileInputStream(dd);

//设置输出的格式

response.reset();

response.setContentType("application/x-msdownload");

response.setContentLength((int)filelength);

response.addHeader("Content-Disposition","attachment; filename=\"" + toUtf8String(filename) + "\"");

//循环取出流中的数据

byte[] b = new byte[100];

int len;

while((len=inStream.read(b)) 0)

response.getOutputStream().write(b,0,len);

inStream.close();

out.clear();

out = pageContext.pushBody();

}

%

：a href="d.jsp"aa/a

上面的那个是用流写的 但是也可以用超链接下载

你写上文件的路径就可以了