Java：使用URL下载图片为何图片下载不完全呢？

问题描述

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？

问题解答

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

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。

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。