java – XHTML到PDF使用fly-saucer如何缓存css

在我的生产管道中,我需要从 HTML生成几百个PDF.对于这种情况,我首先将HTML转换为XHTML.
比我将’已清理’的XHTML和uri传递给渲染器.

由于* .css和imageFiles对于所有XHTML文件都是相同的,所以我不需要在处理文件时解决它们.
我成功使用以下代码缓存图像.如何缓存.css文件呢？我想避免将所有文件放入我的类路径中.

ITextRenderer renderer = new ITextRenderer();

ResourceLoaderUserAgent callback = new ResourceLoaderUserAgent(renderer.getOutputDevice());
callback.setSharedContext(renderer.getSharedContext());

for (MyObject myObject : myObjectList) {

    OutputStream os = new FileOutputStream(tempFile);

    final DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
    documentBuilderFactory.setValidating(false);
    DocumentBuilder builder = documentBuilderFactory.newDocumentBuilder();
    org.w3c.dom.Document document = builder.parse(myObject.getLocalPath); // full path to .xhtml

    renderer.getSharedContext().setUserAgentCallback(callback);

    renderer.setDocument(document,myObject.getUri());
    renderer.layout();
    renderer.createPDF(os);

    os.flush();
    os.close();
}
    ...


private static class ResourceLoaderUserAgent extends ITextUserAgent
{
    public ResourceLoaderUserAgent(ITextOutputDevice outputDevice) {
        super(outputDevice);
    }

    protected InputStream resolveAndOpenStream(String uri) {
        InputStream is = super.resolveAndOpenStream(uri);
        System.out.println("IN resolveAndOpenStream() " + uri);

        return is;
    }
}

解决方法

在这里遇到同样问题的人是我如何解决它.
由于我无法在我的CustomUserAgent中缓存* .css文件,我必须找到另一种方法.我的解决方案使用 Squid作为http-proxy来缓存所有常用资源.

在我的CustomUserAgent中,我只需要通过传递proxy-object来访问此代理.

public class ResourceLoaderUserAgent extends ITextUserAgent {

public ResourceLoaderUserAgent(ITextOutputDevice outputDevice) {
    super(outputDevice);
}

protected InputStream resolveAndOpenStream(String uri) {    

    HttpURLConnection connection = null;
    URL proxyUrl = null;
    try {
        Proxy proxy = new Proxy(Proxy.Type.HTTP,new InetSocketAddress("localhost",3128));
        proxyUrl = new URL(uri);
        connection = (HttpURLConnection) proxyUrl.openConnection(proxy);
        connection.connect();

    } catch (Exception e) {
        throw new RuntimeException(e);
    }

    java.io.InputStream is = null;
    try {
        is = connection.getInputStream();
    } catch (java.net.MalformedURLException e) {
        XRLog.exception("bad URL given: " + uri,e);
    } catch (java.io.FileNotFoundException e) {
        XRLog.exception("item at URI " + uri + " not found");
    } catch (java.io.IOException e) {
        XRLog.exception("IO problem for " + uri,e);
    }

    return is;
}
}

缓存：

resolving css took 74 ms
resolving images took 225 ms

未缓存：

resolving css took 15466 ms
resolving images took 11236 ms

如您所见,缓存和未缓存资源之间的差异很大