Java：使用URL下载图片为何图片下载不完全呢？

Question

public class Client {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://www.iteye.com/upload/logo/user/1177132/a7159cc1-b11a-3122-9a9d-5183d6c6ba99.jpg");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setConnectTimeout(5 * 1000);
            InputStream inputStream = connection.getInputStream();
            byte[] tmp = new byte[1024];
            int length;
            OutputStream outputStream = new FileOutputStream("E:" + File.separator + "eee.jpg");
            while ((length = inputStream.read(tmp)) != -1) {
                outputStream.write(tmp, 0, length);
            }
            outputStream.close();
            inputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

图片URL：
http://www.iteye.com/upload/l...
图片有3K，但我下载后图片只有2K而且图片是错误的这是为什么呢？

Answer 1

你把代码改成这样试试

public class Client {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://www.iteye.com/upload/logo/user/1177132/a7159cc1-b11a-3122-9a9d-5183d6c6ba99.jpg");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.19 Safari/537.36");
            connection.setConnectTimeout(5 * 1000);
            InputStream inputStream = connection.getInputStream();
            byte[] tmp = new byte[1024];
            int length;
            OutputStream outputStream = new FileOutputStream("E:" + File.separator + "eee.jpg");
            while ((length = inputStream.read(tmp)) != -1) {
                outputStream.write(tmp, 0, length);
            }
            outputStream.close();
            inputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

不添加UA下载下来的文件其实是这样的

Answer 2

outputStream.close()之前，先调用outputStream.flush()，这个方法能强制把输出流缓冲全部写出来。你前边的都没错，就差一步了。

Answer 3

这是我用你的代码读到的东西。

目标禁止了，为connection添加一个user-agent属性吧。