java文件下载保存代码,JAVA下载文件

Java中文件下载该怎么写代码求高手指导

你的上传做了吗？

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);

}

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(); 

  

         } 

  

      }   

}

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response

response.reset();

// 设置response的Header

response.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("" + 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();

}

java如何保存文件

这是我原来做的例子,里面有文件储存的内容,代码不多,给你参考参考.

/**

* 五个按钮的故事，西西哈。

*/

import java.awt.*;

import java.awt.event.*;

import java.io.*;

public class FileMessage extends Frame implements ActionListener

{

private static final long serialVersionUID = 10L;

Dialog dia;

private Panel p;

private File fi;

Process po=null;

private String s;

private TextArea ta;

private FileDialog fd;

private Button b1,b2,b3,b4,b5;

private Button b6;

public FileMessage()

{

super("文本文件处理");

setBackground( Color.LIGHT_GRAY );

setLocation(200,300);

setResizable( false);

setVisible( true);

addWindowListener( new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit( 0);

}

});

}

public void init()

{

ta=new TextArea("\n\n\n\n\n\t\t\t\t文本显示区");

ta.setSize(30,5);

ta.setEditable(false);

add( ta,"North");

p=new Panel();

add( p,"Center");

b1=new Button("浏览");

b2=new Button("保存");

b3=new Button("清空");

b4=new Button("关闭");

b5=new Button("独立打开");

b6=new Button("确定");

p.add(b1);

p.add(b2);

p.add(b3);

p.add(b4);

p.add(b5);

b1.addActionListener(this);

b2.addActionListener(this);

b3.addActionListener(this);

b4.addActionListener(this);

b5.addActionListener(this);

b6.addActionListener(this);

fd=new FileDialog(this,"请选择文件",FileDialog.LOAD);

fd.setDirectory("f:\\note");

pack();

dia=new Dialog(this,"注意",true);

dia.setLayout(new BorderLayout());

Panel p1=new Panel();

p1.add( b6);

dia.add(new Label(" 请先选择文件"),BorderLayout.CENTER);

dia.add( p1,BorderLayout.SOUTH);

dia.addWindowListener( new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

dia.setVisible( false);

}

});

dia.setLocation(310,370);

dia.setSize(200,130);

}

public static void main(String[] args)

{

new FileMessage().init();

}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==b1)

{

fd.setVisible(true);

s=fd.getDirectory()+fd.getFile();

fi=new File(s);

byte[] b=new byte[(int)fi.length()];

try

{

new FileInputStream(fi).read(b);

ta.setText(new String(b,0,(int)fi.length()));

}

catch(Exception e1){}

ta.setEditable(true);

}

else if(e.getSource()==b2)

{

try

{

if(ta.getText().equals("保存成功")||ta.getText() .equals( ""))

{}

else

{

new FileOutputStream(fi).write(ta.getText().getBytes());

ta.setText("保存成功");

ta.setEditable(false);

}

}

catch(FileNotFoundException e1)

{

ta.setText(e1.getMessage());

}

catch(IOException e1)

{

ta.setText("出现IOException异常");

}

}

else if(e.getSource()==b4)

System.exit(0);

else if(e.getSource()==b3)

{

ta.setText("");

ta.setEditable( false);

}

else if(e.getSource()==b5)

{

if(s==null)

{

dia.setVisible(true);

}

else

{

try

{

po=Runtime.getRuntime().exec("notepad.exe "+s);

}

catch(Exception ei)

{}

}

}

else if(e.getSource() ==b6)

{

dia.setVisible(false);

}

}

}