java实现下载文件代码 java实现下载文件代码的方法

Java中文件下载该怎么写代码求高手指导

if (upfile.exists()) {

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);

}

相关问答

Q1: java中怎么实现下载功能，最好能有代码

private File uploadify;

private String uploadifyFileName;

public String uploadFile1() throws Exception {

String extName = "";// 扩展名

String newFileName = "";// 新文件名

String nowTime = df.format(new Date());// 当前时间

String random = "-" + (Math.round(Math.random() * 9000) + 1000);// 随机函数

String path = "uploads/" + nowTime.substring(0, 6) + "/"

+ nowTime.substring(0, 8) + "/";// 保存路径

String savePath = ServletActionContext.getServletContext().getRealPath(

"");

savePath = savePath.replace("\\", "/");

if (!savePath.substring(savePath.length()).equals("/"))

savePath = savePath + "/";

savePath = savePath + path;

// 获取扩展名

if (uploadifyFileName.lastIndexOf(".") = 0) {

extName = uploadifyFileName.substring(uploadifyFileName

.lastIndexOf("."));

}

newFileName = uploadifyFileName.substring(0,

uploadifyFileName.lastIndexOf("."))

+ nowTime.substring(8) + random + extName;

File file = new File(savePath);

if (!file.exists())

file.mkdirs();

uploadify.renameTo(new File(savePath + newFileName));

/*

* HttpServletResponse response = ServletActionContext.getResponse();

* response.setCharacterEncoding("utf-8");

* response.getWriter().print(uploadifyFileName+"上传成功");

*/

String ctx = Struts2Utils.getRequest().getContextPath();

Struts2Utils.renderText(ctx + "/" + path + newFileName);

Wenjdetail detail = new Wenjdetail();

String pt = path + newFileName;

detail.setName(uploadifyFileName);

detail.setUrl(pt);

wenjdetailManager.saveWenjdetail(detail);

HttpServletResponse response = ServletActionContext.getResponse();

response.setCharacterEncoding("utf-8");

response.getWriter().print("," + detail.getId());

return null; // 这里不需要页面转向，所以返回空就可以了

}

Q2: JAVA文件下载如何实现

在http协议下，实现下载一般就两种方法，一个采用cont-type="";此种方法为附件的方式下载；；

另一种较简单，就是你只需要点下载按钮然后跳转到服务器的那个文件路劲就可以了，浏览器自动回进行下载..

Q3: 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();

}

}

}

}

Q4: JAVA实现文件下载,浏览器端得到数据没反应

建议你

1.重启电脑

2.检查网速

3.换个浏览器试试，试试腾讯电脑管家-软件管理-软件仓库-浏览器-找到你想要的下载就行了

java实现下载文件代码的介绍就聊到这里吧，感谢你花时间阅读本站内容，更多关于java实现下载文件代码的方法、java实现下载文件代码的信息别忘了在本站进行查找喔。