如何使用jsoup从一个需要登陆的网站下载图片

使用Firebug抓取浏览器中浏览图片时发送的请求包然后再根据其格式，使用URLConnection构造发送带cookies的请求包即可。

/**
     * 下载图片从URL
     *
     * @param img 图片对象
     * @param imgFile 代写入文件对象
     * @throws MalformedURLException 获取URL异常
     * @throws IOException URLConnection获取异常
     */
    public void downloadImg(Img img, File imgFile) throws MalformedURLException, IOException {
        URL url = new URL(img.getUrl());
        URLConnection uc = url.openConnection();
        uc.setConnectTimeout(Setting._Download_Img_TimeOut); // 设置下载图片超时时间
        uc.setRequestProperty("accept", "image/png,image/*;q=0.8,*/*;q=0.5");
        uc.setRequestProperty("accept-encoding", "gzip, deflate");
        uc.setRequestProperty("accept-language", "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3");
        uc.setRequestProperty("connection", "keep-alive");
        uc.setRequestProperty("cookie", PixivLogin.userCookies.toString());//这里是cookie部分
        uc.setRequestProperty("dnt", "1");
        uc.setRequestProperty("host", "i2.pixiv.net");
        uc.setRequestProperty("user-agent", Setting._DownLoadImgClient_UserAgent);

        uc.setDoInput(true);
        uc.setDoOutput(true);
        System.out.println("图片获取成功");
        System.out.println("开始写入硬盘");
        InputStream is = uc.getInputStream();
        FileOutputStream out = new FileOutputStream(imgFile);
        //BufferedOutputStream bout = new BufferedOutputStream(out);
        int i = 0;

        while ((i = is.read()) != -1) {
            out.write(i);
        }
        is.close();
        System.out.println(img.getName() + "写入完毕 " + imgFile.length());
    }