java下载网络上某图片

URL url = new URL("图片地址");
				File outFile = new File(“图片保存到本地路径”);
				OutputStream os = new FileOutputStream(outFile);
				InputStream is = url.openStream();
				byte[] buff = new byte[1024];
				while(true) {
					int readed = is.read(buff);
					if(readed == -1) {
						break;
					}
					byte[] temp = new byte[readed];
					System.arraycopy(buff, 0, temp, 0, readed);
					os.write(temp);
				}
				is.close(); 
                                os.close();

另外参考：

http://www.cnblogs.com/blue-cherry/archive/2011/12/09/2282571.html