异步任务下载图片，带进度条

inputStream = response.getEntity().getContent();

long file_length = response.getEntity().getContentLength();

int len = 0;

byte[] data = new byte[1024];

int total_length = 0;

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

while ((len = inputStream.read(data)) != -1) {

total_length += len;

int value = (int) ((total_length / (float) file_length) * 100);

publishProgress(value);

outputStream.write(data, 0, len);

}