java代码实现下载功能,java 下载功能

java如何实现超链接下载

java实现超链接下载方法如下：

response.setHeader("Content-disposition","attachment;filename="下载的文件名字);

备注：让response调用setheader方法添加下载的头给客户的浏览器，浏览器收到该头后就会打开相应的下载对话框。

相关问答

Q1: Struts1框架 用Java代码实现文件下载 不弹出下载框 代码：

下载代码：

这里我使用的是SpringMVC，不过它在这里的唯一用途就是用来获取ServletContext对象，这个对象的用途，下面实例中有说明

下载，需要用到两个jar包：commons-fileupload.jar和commons-io.jar

Java代码

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.context.ServletContextAware;

import javax.servlet.ServletContext;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServletResponse;

import java.io.*;

@Controller

public class FileController implements ServletContextAware{

//Spring这里是通过实现ServletContextAware接口来注入ServletContext对象

private ServletContext servletContext;

@RequestMapping("file/download")

public void fileDownload(HttpServletResponse response){

//获取网站部署路径(通过ServletContext对象)，用于确定下载文件位置，从而实现下载

String path = servletContext.getRealPath("/");

//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型

response.setContentType("multipart/form-data");

//2.设置文件头：最后一个参数是设置下载文件名(假如我们叫a.pdf)

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

ServletOutputStream out;

//通过文件路径获得File对象(假如此路径中有一个download.pdf文件)

File file = new File(path + "download/" + "download.pdf");

try {

FileInputStream inputStream = new FileInputStream(file);

//3.通过response获取ServletOutputStream对象(out)

out = response.getOutputStream();

int b = 0;

byte[] buffer = new byte[512];

while (b != -1){

b = inputStream.read(buffer);

//4.写到输出流(out)中

out.write(buffer,0,b);

}

inputStream.close();

out.close();

out.flush();

} catch (IOException e) {

e.printStackTrace();

}

}

@Override

public void setServletContext(ServletContext servletContext) {

this.servletContext = servletContext;

}

}

Q2: java下载功能实现

楼主得在后台的控制器中用reponse的输出流转化一下，我给你个例子。

InputStream fis = new BufferedInputStream(new FileInputStream(filePath));byte[] buffer = new byte[fis.available()];fis.read(buffer);fis.close();response.reset();response.addHeader("Content-Disposition", "attachment;filename=" + new String(fileName.getBytes("gbk"),"ISO-8859-1"));response.addHeader("Content-Length", "" + excelFile.length());OutputStream toClient = new BufferedOutputStream(response.getOutputStream());response.setContentType("application/octet-stream");toClient.write(buffer);toClient.flush();toClient.close();

求采纳为满意回答。

Q3: java 写一个action 能实现点击事件后浏览器能自动下载xml文件的功能！！急

方法一:调用浏览器下载文件

下面Action里的代码可以用调用浏览器进行下载xml文件

import java.awt.Desktop;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.net.URI;

import javax.swing.JButton;

import javax.swing.JFrame;

public class DownLoadDemo extends JFrame {

JButton jb;

public DownLoadDemo() {

jb = new JButton("Download");

jb.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

try {

String path = "网络xml的地址";

URI uri = new URI(path);

Desktop.getDesktop().browse(uri);

} catch (Exception e1) {

e1.printStackTrace();

}

}

});

add(jb);

setTitle("调用浏览器下载");

setBounds(380, 380,230,80);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setVisible(true);

}

public static void main(String[] args) {

new DownLoadDemo();

}

}

当时上述下载方式,可能会弹出提示,比如保存位置等.

方法二:使用IO和net下载文件.这种方式没有调用浏览器,下载过程,不会弹出提示灯

import java.io.FileOutputStream;

import java.io.InputStream;

import java.net.URL;

import java.net.URLConnection;

import java.util.Date;

public class DownLoadDemo {

public static void main(String[] args) throws Exception {

String str = "XML的网络地址";

URL url = new URL(str);

URLConnection urlconn = url.openConnection();

urlconn.connect();

InputStream is = urlconn.getInputStream();

FileOutputStream fos = new FileOutputStream("qq.exe");

byte[] buf = new byte[4096];

int length = 0;

//System.out.println("开始下载时间："+new Date());

while((length=is.read(buf))!=-1){

fos.write(buf, 0, length);

}

fos.close();

is.close();

//System.out.println("下载完成时间："+new Date());

}

}

Q4: java 如何实现下载功能

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();

}

}

}

}

参考一下这个代码。