pdf文件之itextpdf插入html内容以及中文解决方案

简述

目前网上已经有很多种html文件直接转pdf的技术帖子，但是很少有直接将部分html作为段落插入到pdf中，而且也没有一个可以很好的解决中文显示的问题。

因此今天上午围绕这个问题进行了研究，把解决方案分享给大家。

itextpdf基础操作请访问：http://www.cnblogs.com/mvilplss/p/5640598.html

感谢：http://gridmix.blog.51cto.com/4764051/1229585

实现思路

如果想插入html片段，我们使用一个类的静态方法：

         String html = "<div style='color:green;font-size:20px;'>你好世界！hello world !</div>";
         Paragraph context = new Paragraph();
         ElementList elementList =XMLWorkerHelper.parseToElementList(htmlString, null);
         for (Element element : elementList) {
             context.add(element);
         }
         document.add(context);

不过你会发现不能显示中文，这个问题网上有很多种解决方法，但是都不好使。

查看XMLWorkerHelper.parseToElementList(htmlString, null)这个方法的源码，发现

CssAppliers cssAppliers = new CssAppliersImpl(FontFactory.getFontImp());可以进行字体的更换。

 public static ElementList parseToElementList(String html, String css) throws IOException {
         // CSS
         CSSResolver cssResolver = new StyleAttrCSSResolver();
         if (css != null) {
             CssFile cssFile = XMLWorkerHelper.getCSS(new ByteArrayInputStream(css.getBytes()));
             cssResolver.addCss(cssFile);
         }

         // HTML
         CssAppliers cssAppliers = new CssAppliersImpl(FontFactory.getFontImp());//这里可以下手对字体进行操作
         HtmlPipelineContext htmlContext = new HtmlPipelineContext(cssAppliers);
         htmlContext.setTagFactory(Tags.getHtmlTagProcessorFactory());
         htmlContext.autoBookmark(false);

         // Pipelines
         ElementList elements = new ElementList();
         ElementHandlerPipeline end = new ElementHandlerPipeline(elements, null);
         HtmlPipeline htmlPipeline = new HtmlPipeline(htmlContext, end);
         CssResolverPipeline cssPipeline = new CssResolverPipeline(cssResolver, htmlPipeline);

         // XML Worker
         XMLWorker worker = new XMLWorker(cssPipeline, true);
         XMLParser p = new XMLParser(worker);
         p.parse(new ByteArrayInputStream(html.getBytes()));

         return elements;
     }

因此我们就想到重写XMLWorkerFontProvider类的getFont(*)方法，对于没有显示声明css样式的字体，默认使用undefine字体样式进行设置默认字体。

 public class MyXMLWorkerHelper {
     public static class MyFontsProvider extends XMLWorkerFontProvider {
         public MyFontsProvider() {
             super(null, null);
         }

         @Override
         public Font getFont(final String fontname, String encoding, float size, final int style) {

             String fntname = fontname;
             if (fntname == null) {
                 fntname = "宋体";
             }
             return super.getFont(fntname, encoding, size, style);
         }
     }

     public static ElementList parseToElementList(String html, String css) throws IOException {
         // CSS
         CSSResolver cssResolver = new StyleAttrCSSResolver();
         if (css != null) {
             CssFile cssFile = XMLWorkerHelper.getCSS(new ByteArrayInputStream(css.getBytes()));
             cssResolver.addCss(cssFile);
         }

         // HTML
         MyFontsProvider fontProvider = new MyFontsProvider();
         CssAppliers cssAppliers = new CssAppliersImpl(fontProvider);
         HtmlPipelineContext htmlContext = new HtmlPipelineContext(cssAppliers);
         htmlContext.setTagFactory(Tags.getHtmlTagProcessorFactory());
         htmlContext.autoBookmark(false);

         // Pipelines
         ElementList elements = new ElementList();
         ElementHandlerPipeline end = new ElementHandlerPipeline(elements, null);
         HtmlPipeline htmlPipeline = new HtmlPipeline(htmlContext, end);
         CssResolverPipeline cssPipeline = new CssResolverPipeline(cssResolver, htmlPipeline);

         // XML Worker
         XMLWorker worker = new XMLWorker(cssPipeline, true);
         XMLParser p = new XMLParser(worker);
         html = html.replace("<br>", "").replace("<hr>", "").replace("<img>", "").replace("<param>", "")
                 .replace("<link>", "");
         p.parse(new ByteArrayInputStream(html.getBytes()));

         return elements;
     }

 }

因为XMLWork不支持html的单标签，所以要对但标签进行过滤。不然就会报错：Invalid nested tag div found, expected closing tag br