java 從網絡Url中下載文件

package test;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Date;

public class downLoadFromUrlClass {
/**
* 從網絡Url中下載文件
* 
* @param urlStr
* @param fileName
* @param savePath
* @throws IOException
*/
public static void downLoadFromUrl(String urlStr, String fileName,
String savePath) throws IOException {
URL url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
// 設置超時間爲3秒
conn.setConnectTimeout(3 * 1000);
// 防止屏蔽程序抓取而返回403錯誤
conn.setRequestProperty("User-Agent",
"Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");

// 得到輸入流
InputStream inputStream = conn.getInputStream();
// 獲取自己數組
byte[] getData = readInputStream(inputStream);

// 文件保存位置
File saveDir = new File(savePath);
if (!saveDir.exists()) {
saveDir.mkdir();
}
File file = new File(saveDir + File.separator + fileName);
FileOutputStream fos = new FileOutputStream(file);
fos.write(getData);
if (fos != null) {
fos.close();
}
if (inputStream != null) {
inputStream.close();
}

System.out.println("下載地址：" + url + "\ndownload success");

}

/**
* 從輸入流中獲取字節數組
* 
* @param inputStream
* @return
* @throws IOException
*/
public static byte[] readInputStream(InputStream inputStream)
throws IOException {
byte[] buffer = new byte[1024];
int len = 0;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while ((len = inputStream.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
bos.close();
return bos.toByteArray();
}

/**
* 測試
* 
* @param args
*/
public static void main(String[] args) {
try {
downLoadFromUrl(
"http://218.17.158.39:8101/dzfp-platform/downloadAction.do?method=download&request=CHnK39H87yYrpoya*COhxRO*BDMV4Iz1EzA6qJimpAmsmq1cxtp-LhkDfmVxM1rb5SpT9HbpBi8_%5EBAGacjHgdc",
"電子發票_" + new Date().getTime() + ".pdf", "d:/resource");
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}