我也覆盖了 ITextUserAgent - 从源头上看,这就是 ITextRenderer 使用的。您必须在构造函数中提供输出设备,您可以从渲染器对象中获取该输出设备。另一个问题是您必须使用 setter 方法显式设置“共享上下文” - 否则您将在渲染期间获得 NPE。这是设置对象的代码:
ITextRenderer renderer = new ITextRenderer();
MyUserAgentCallback uac = new MyUserAgentCallback(renderer.getOutputDevice());
uac.setSharedContext(renderer.getSharedContext());
renderer.getSharedContext().setUserAgentCallback(uac);
此外,这是 MyUserAgentCallback 的基本思想,使用基本身份验证:
private static class MyUserAgentCallback extends ITextUserAgent
{
public MyUserAgentCallback(ITextOutputDevice outputDevice)
{
super(outputDevice);
}
@Override
protected InputStream resolveAndOpenStream(String uri)
{
if (_isProtectedResource(uri))
{
java.io.InputStream is = null;
uri = resolveURI(uri);
try {
URL url = new URL(uri);
String encoding = new BASE64Encoder().encode ("username:password".getBytes());
URLConnection uc = url.openConnection();
uc.setRequestProperty ("Authorization", "Basic " + encoding);
is = uc.getInputStream();
Log.debug("got input stream");
}
catch (java.net.MalformedURLException e) {
Log.error("bad URL given: " + uri, e);
}
catch (java.io.FileNotFoundException e) {
Log.error("item at URI " + uri + " not found");
}
catch (java.io.IOException e) {
Log.error("IO problem for " + uri, e);
}
return is;
}
else
{
return super.resolveAndOpenStream(uri);
}
}
private boolean _isProtectedResource(String uri)
{
// does this require authentication?
}
}