import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class UrlResource 
{
public static void main(String[] args){
try {
System.out.println(UrlResource.getUrlDetail("http://www.baidu.com",true));
saveUrlFile("http://www.baidu.com/img/baidu_jgylogo3.gif", "D:\\1.gif");
} catch (Exception e) {
e.printStackTrace();
}
}
//获取网络文件，转存到fileDes中，fileDes需要带文件后缀名
public static void saveUrlFile(String fileUrl,String fileDes) throws Exception
{
File toFile = new File(fileDes);
if (toFile.exists())
{
// throw new Exception("file exist");
return;
}
toFile.createNewFile();
FileOutputStream outImgStream = new FileOutputStream(toFile);
outImgStream.write(getUrlFileData(fileUrl));
outImgStream.close();
}
//获取链接地址文件的byte数据
public static byte[] getUrlFileData(String fileUrl) throws Exception
{
URL url = new URL(fileUrl);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
httpConn.connect();
InputStream cin = httpConn.getInputStream();
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = cin.read(buffer)) != -1) {
outStream.write(buffer, 0, len);
}
cin.close();
byte[] fileData = outStream.toByteArray();
outStream.close();
return fileData;
}
//获取链接地址的字符数据，wichSep是否换行标记
public static String getUrlDetail(String urlStr,boolean withSep) throws Exception
{
URL url = new URL(urlStr);
HttpURLConnection httpConn = (HttpURLConnection)url.openConnection();
httpConn.connect();
InputStream cin = httpConn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(cin,"UTF-8"));
StringBuffer sb = new StringBuffer();
String rl = null;
while((rl = reader.readLine()) != null)
{
if (withSep)
{
sb.append(rl).append(System.getProperty("line.separator"));
}
else
{
sb.append(rl);
}
}
return sb.toString();
}
}// 禁止图像缓存
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
文章详细参考：
http://blog.csdn.net/pandakong/article/details/7430844