使HttpURLConnection加载带有图像的网页 [英] Make HttpURLConnection load web pages with images

问题描述

当前，我正在使用HttpURLConnection加载远程网页并将其呈现给我的客户端(使用InputStream进行HttpResponse的outputStream传输)，它可以正确加载html但会跳过图像，如何解决?

Currently I'm using HttpURLConnection for load remote web page and present to my clients (using InputStream to HttpResponse's outputStream transfer), it loads html correctly but skips images, how to fix it?

谢谢

推荐答案

您需要以这种方式操作HTML，以便同时代理Intranet域上的所有资源URL.例如. HTML中的以下所有资源参考

You need to manipulate the HTML that way so that all resource URLs on the intranet domain are proxied as well. E.g. all of the following resource references in HTML

<base href="http://intranet.com/" />
<script src="http://intranet.com/script.js"></script>
<link href="http://intranet.com/style.css" />
<img src="http://intranet.com/image.png" />
<a href="http://intranet.com/page.html">link</a>

应该以这种方式在HTML中进行更改，这样它们才能通过您的代理servlet，例如

should be changed in the HTML that way so that they go through your proxy servlet instead, e.g.

<base href="http://example.com/proxy/" />
<script src="http://example.com/proxy/script.js"></script>
<link href="http://example.com/proxy/style.css" />
<img src="http://example.com/proxy/image.png" />
<a href="http://example.com/proxy/page.html">link</a>

诸如 Jsoup 之类的HTML解析器在此方面非常有用.您可以在代理Servlet中执行以下操作，我假设它已映射到/proxy/*的URL模式上.

A HTML parser like Jsoup is extremely helpful in this. You can do as follows in your proxy servlet which is, I assume, mapped on an URL pattern of /proxy/*.

String intranetURL = "http://intranet.com";
String internetURL = "http://example.com/proxy";

if (request.getRequestURI().endsWith(".html")) { // A HTML page is requested.
    Document document = Jsoup.connect(intranetURL + request.getPathInfo()).get();

    for (Element element : document.select("[href]")) {
        element.attr("href", element.absUrl("href").replaceFirst(intranetURL, internetURL));
    }

    for (Element element : document.select("[src]")) {
        element.attr("src", element.absUrl("src").replaceFirst(intranetURL, internetURL));
    }

    response.setContentType("text/html;charset=UTF-8");
    response.setCharacterEncoding("UTF-8");
    resposne.getWriter().write(document.html());
}
else { // Other resources like images, etc.
    URLConnection connection = new URL(intranetURL + request.getPathInfo()).openConnection();

    for (Map.Entry<String, List<String>> header : connection.getHeaderFields().entrySet()) {
        for (String value : header.getValue()) {
            response.addHeader(header.getKey(), value);
        }
    }

    InputStream input = connection.getInputStream();
    OutputStream output = response.getOutputStream();
    // Now just copy input to output.
}

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