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 = "http://www.7cd.cn/QingTengPics/倩女幽魂.mp3"//MP3下载的地址
String path ="http://img.99luna.com/music/%CF%EB%C4%E3%BE%CD%D0%B4%D0%C5.mp3"
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 = 0threadid<=threadsizethreadid++){
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", "attachmentfilename=" + 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", "attachmentfilename=\"" + 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", "inlinefilename=" + 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", "attachmentfilename=" + f.getName())
}
OutputStream out = response.getOutputStream()
while ((len = br.read(buf)) >0)
out.write(buf, 0, len)
br.close()
out.close()
}
