Java io流 从网络读取图片并保存至本地

package getUrlPic;
 
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
 
public class GetUrlPic {
    
    public static void main(String[] args) throws Exception {  
        //new一个URL对象  
        URL url = new URL("http://www.gz135.cn/data/attachment/forum/201702/13/165605xyayykq5vy4h81vy.jpg");  
        //打开链接  
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();  
        //设置请求方式为"GET"  
        conn.setRequestMethod("GET");  
        //超时响应时间为5秒  
        conn.setConnectTimeout(5 * 1000);  
        //通过输入流获取图片数据  
        InputStream inStream = conn.getInputStream();  
        //得到图片的二进制数据，以二进制封装得到数据，具有通用性  
        byte[] data = readInputStream(inStream);  
        //new一个文件对象用来保存图片，默认保存当前工程根目录  
        File imageFile = new File("pic20170419.jpg");  
        //创建输出流  
        FileOutputStream outStream = new FileOutputStream(imageFile);  
        //写入数据  
        outStream.write(data);  
        //关闭输出流  
        outStream.close();  
    }  
    public static byte[] readInputStream(InputStream inStream) throws Exception{  
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();  
        //创建一个Buffer字符串  
        byte[] buffer = new byte[1024];  
        //每次读取的字符串长度，如果为-1，代表全部读取完毕  
        int len = 0;  
        //使用一个输入流从buffer里把数据读取出来  
        while( (len=inStream.read(buffer)) != -1 ){  
            //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度  
            outStream.write(buffer, 0, len);  
        }  
        //关闭输入流  
        inStream.close();  
        //把outStream里的数据写入内存  
        return outStream.toByteArray();  
    }  
 
}