java反盗链

下面是完整的代码。
package cn.searchphoto.util;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.zip.GZIPInputStream;
/**
* 下载远程网站的图片，通过设置Referer反反盗链。
*
* @author JAVA世纪网(java2000.net, laozizhu.com)
*/
public class ImageDownloader {
/**
* 下载文件到指定位置
* @param imgurl 下载连接
* @param f 目标文件
* @return 成功返回文件，失败返回null
*/
public static File download(String imgurl, File f) {
try {
URL url = new URL(imgurl);
URLConnection con = url.openConnection();
int index = imgurl.indexOf("/", 10);
con.setRequestProperty("Host", index == -1 ? imgurl.substring(7) : imgurl.substring(7, index));
con.setRequestProperty("Referer", imgurl);
InputStream is = con.getInputStream();
if (con.getContentEncoding() != null && con.getContentEncoding().equalsIgnoreCase("gzip")) {
is = new GZIPInputStream(con.getInputStream());
}
byte[] bs = new byte[1024];
int len = -1;
OutputStream os = new FileOutputStream(f);
try {
while ((len = is.read(bs)) != -1) {
os.write(bs, 0, len);
}
} finally {
try {
os.close();
} catch (Exception ex) {}
try {
is.close();
} catch (Exception ex) {}
}
return f;
} catch (Exception ex) {
ex.printStackTrace();
return null;
}
}
}