Java 断点续传

本文从http://www.blogjava.net/breezedancer/archive/2007/07/19/131264.html转载
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
//断点续传
public class Download {
public static void down(String URL, long nPos, String savePathAndFile) {
try {
URL url = new URL(URL);
HttpURLConnection httpConnection = (HttpURLConnection) url
.openConnection();
// 设置User-Agent
httpConnection.setRequestProperty("User-Agent", "NetFox");
// 设置断点续传的开始位置
httpConnection.setRequestProperty("RANGE", "bytes=" + nPos);
// 获得输入流
InputStream input = httpConnection.getInputStream();
RandomAccessFile oSavedFile = new RandomAccessFile(savePathAndFile,
"rw");
// 定位文件指针到nPos位置
oSavedFile.seek(nPos);
byte[] b = new byte[1024];
int nRead;
// 从输入流中读入字节流，然后写到文件中
while ((nRead = input.read(b, 0, 1024)) > 0) {
(oSavedFile).write(b, 0, nRead);
}
httpConnection.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static long getRemoteFileSize(String url) {
long size = 0;
try {
HttpURLConnection conn = (HttpURLConnection) (new URL(url))
.openConnection();
size = conn.getContentLength();
conn.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
return size;
}
public static void main(String[] args) {
String url = "http://www.blogjava.net/bree