java使用freemarker模板生成html，再生成pdf

1.freemarker模板生成html

1. 添加Maven依赖

在pom.xml文件中添加以下依赖：

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>

2. 创建Freemarker模板

新建一个HTML文件，例如table.ftl，然后在其中编写HTML模板，包括表格的头部、内容和尾部等部分。具体可以参考下面这个例子：

<table border="1"><thead><tr><th>ID</th><th>Name</th><th>Age</th></tr></thead><tbody><#list users as user><tr><td>${user.id}</td><td>${user.name}</td><td>${user.age}</td></tr></#list></tbody>
</table>

上面的模板中使用了Freemarker的指令语法来实现动态生成表格内容，包括使用<#list>标签来遍历用户列表，并使用${}语法来输出用户信息。

3. 创建Controller方法

在Controller中编写一个方法来获取用户列表，然后渲染上面的模板并返回HTML内容。示例代码如下：

@Controller
public class UserController {@GetMapping("/users")public String userList(Model model) {List<User> users = new ArrayList<>();users.add(new User(1, "Tom", 18));users.add(new User(2, "Jerry", 20));users.add(new User(3, "John", 22));model.addAttribute("users", users);return "table";}
}

上面的方法使用@GetMapping注解来处理请求，然后创建一个用户列表，并将其添加到模型中。最后返回table字符串，代表要使用的HTML模板文件。

4. 运行项目

运行Spring Boot应用程序，然后使用浏览器访问http://localhost:8080/users，即可看到动态生成的HTML表格。

注意：上面的例子仅供参考，实际应用中需要根据自己的需求进行修改扩展。

2.利用iText将生成的HTML转换为PDF文件

理解了freemarker生成html的步骤以后，就可以利用iText把html生成pdf文件了。

1. 编写转换代码
   添加Maven依赖
   在pom.xml文件中添加以下依赖：

<dependency>
<groupId>com.itextpdf.tool</groupId><artifactId>xmlworker</artifactId><version>5.5.1</version>
</dependency><dependency><groupId>com.itextpdf</groupId><artifactId>itext-asian</artifactId><version>5.2.0</version>
</dependency><!-- 支持css样式渲染 -->
<dependency><groupId>org.xhtmlrenderer</groupId><artifactId>flying-saucer-pdf-itext5</artifactId><version>9.0.9</version>
</dependency>

2. 编写转换代码
   在SpringBoot应用程序中创建一个Service或者Controller类，然后编写HTML转PDF的代码。

freeMarker转换为html的方法：

public class HtmlGenerator {public static String generate(String template, Map<String, Object> variables) throws IOException, TemplateException, IOException {Configuration config = new Configuration(Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS);// 指定FreeMarker模板文件的位置config.setClassForTemplateLoading(HtmlGenerator.class, "/filePath");//读取模板文件地址config.setDefaultEncoding("UTF-8");//获取模板文件Template tp = config.getTemplate(template);StringWriter stringWriter = new StringWriter();BufferedWriter writer = new BufferedWriter(stringWriter);tp.setEncoding("UTF-8");//把map数据写入tp.process(variables, writer);String htmlStr = stringWriter.toString();writer.flush();writer.close();return htmlStr;}
}

/filePath为项目中的ftl文件相对路径。
html生成pdf的方法：

public class PdfDocumentGenerator {private static final Logger logger = LoggerFactory.getLogger(PdfDocumentGenerator.class);/*** Output a pdf to the specified outputstream* * @param htmlStr*            the htmlstr* @param out*            the specified outputstream* @throws Exception*/public static void generate(String htmlStr, OutputStream out)throws Exception {DocumentBuilderFactory df = DocumentBuilderFactory.newInstance();df.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, ""); // Compliantdf.setAttribute(XMLConstants.ACCESS_EXTERNAL_SCHEMA, ""); // compliantDocumentBuilder builder = df.newDocumentBuilder();org.w3c.dom.Document doc = builder.parse(new ByteArrayInputStream(htmlStr.getBytes()));ITextRenderer renderer = new ITextRenderer();renderer.setDocument(doc, null);renderer.layout();renderer.createPDF(out);out.close();}public static void generatePlus(String htmlStr, OutputStream out) throws IOException, DocumentException {final String charsetName = "UTF-8";Document document = new Document(PageSize.A4, 30, 30, 30, 30);document.setMargins(30, 30, 30, 30);PdfWriter writer = PdfWriter.getInstance(document, out);document.open();// html内容解析HtmlPipelineContext htmlContext = new HtmlPipelineContext(new CssAppliersImpl(new XMLWorkerFontProvider() {@Overridepublic Font getFont(String fontname, String encoding,float size, final int style) {if (fontname == null) {fontname = getChineseFont();      }return super.getFont(fontname, encoding, size,style);}})) {@Overridepublic HtmlPipelineContext clone()throws CloneNotSupportedException {HtmlPipelineContext context = super.clone();try {ImageProvider imageProvider = this.getImageProvider();context.setImageProvider(imageProvider);} catch (NoImageProviderException e) {}return context;}};// 图片解析htmlContext.setImageProvider(new AbstractImageProvider() {String rootPath = PdfDocumentGenerator.class.getResource("/").getPath();@Overridepublic String getImageRootPath() {return rootPath;}@Overridepublic Image retrieve(String src) {if (StringUtils.isEmpty(src)) {return null;}try {Image image = Image.getInstance(new File(rootPath, src).toURI().toString());// 图片显示位置image.setAbsolutePosition(400, 400);		if (image != null) {store(src, image);return image;}} catch (Throwable e) {e.printStackTrace();}return super.retrieve(src);}});htmlContext.setAcceptUnknown(true).autoBookmark(true).setTagFactory(Tags.getHtmlTagProcessorFactory());// css解析CSSResolver cssResolver = XMLWorkerHelper.getInstance().getDefaultCssResolver(true);cssResolver.setFileRetrieve(new FileRetrieve() {@Overridepublic void processFromStream(InputStream in,ReadingProcessor processor) throws IOException {try (InputStreamReader reader = new InputStreamReader(in, charsetName)) {int i = -1;while (-1 != (i = reader.read())) {processor.process(i);}} catch (Throwable e) {}}// 解析href@Overridepublic void processFromHref(String href, ReadingProcessor processor) throws IOException {InputStream is = PdfDocumentGenerator.class.getResourceAsStream("/" + href);try (InputStreamReader reader = new InputStreamReader(is,charsetName)) {int i = -1;while (-1 != (i = reader.read())) {processor.process(i);}} catch (Throwable e) {e.printStackTrace();}}});HtmlPipeline htmlPipeline = new HtmlPipeline(htmlContext, new PdfWriterPipeline(document, writer));Pipeline<?> pipeline = new CssResolverPipeline(cssResolver, htmlPipeline);XMLWorker worker = null;worker = new XMLWorker(pipeline, true);XMLParser parser = new XMLParser(true, worker, Charset.forName(charsetName));try (InputStream inputStream = new ByteArrayInputStream(htmlStr.getBytes())) {parser.parse(inputStream, Charset.forName(charsetName));}document.close();}/*** 获取中文字体位置 * @return*/public static String getChineseFont() {String chineseFont = null;chineseFont = Object.class.getResource("/").getPath() + "font/simsun.ttc";if(!new File(chineseFont).exists()){throw new RuntimeException("字体文件不存在！"+chineseFont);}return chineseFont;}
}

运行测试方法：

public class Pdfdest {public static void main(String[] args) throws Exception {String outputFile = "d:/test1.pdf";Map<String, Object> map = new HashMap<>();map.put("XXX", "测试");//生成工具，下面有代码String htmlStr = HtmlGenerator.generate("test.ftl", map);//生成工具，下面有代码OutputStream out = new FileOutputStream(outputFile);PdfDocumentGenerator.generatePlus(htmlStr,out);}
}

准备一个test.ftl放到resource/filePath下，当然字体最好也放到resource/font下，运行时需要使用。
test.ftl的代码如下：

<!DOCTYPE html>
<html>
<head><meta charset="UTF-8"></meta><style>@page {@top-center { content: element(header) }}@page {@bottom-center { content: element(footer) }}.apply {margin: 0 auto;padding: 0 30px;}.title {margin-top: 40px ;text-align: center;font-weight: bold;//字体需要和后台对应上font-family: SimSun;font-weight: bold;font-size: 20px;color: #333333;letter-spacing: 0;}.table {border-collapse: collapse;width: 100%;margin-top: 30px;font-family: SimSun;font-size: 14px;color: #111111;letter-spacing: 0.54px;}.label {background-color: #E6E6E6;width: 20%;}.normaltd {padding: 10px 0;}.maxtd {height: 250px;}.value {width: 30%;padding-left: 10px;}.apply {margin: 0 auto;padding: 0 30px;}.title {margin-top: 40px ;text-align: center;font-weight: bold;//字体需要和后台对应上font-family: SimSun;font-weight: bold;font-size: 20px;color: #333333;letter-spacing: 0;}.table {width: 100%;margin-top: 30px;font-family: SimSun;font-size: 14px;color: #111111;letter-spacing: 0.54px;}.label {background-color: #E6E6E6;width: 20%;}.normaltd {padding: 10px 0;}.maxtd {height: 250px;}.value {width: 30%;padding-left: 10px;}tr {page-break-inside: avoid;page-break-after: auto;}</style>
</head><body style="font-family: SimSun">
<div class="apply"><p class="title">申请单</p><table border="1" cellspacing="0" class="table"><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">XXX</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr ><td valign="middle" colspan="1" class="label maxtd" align="center">XXX</td><td valign="middle" colspan="3" class="maxtd value">${XXX}</td></tr><tr><td colspan="1" class="label normaltd" align="center">XXX</td><td colspan="3" class="normaltd value">${XXX}</td></tr><tr><td colspan="1" class="label normaltd" align="center">XXX</td><td colspan="3" class="normaltd value">${XXX}</td></tr><tr><td colspan="1" class="label normaltd" align="center">XXX</td><td colspan="3" class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">XXX</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr ><td valign="middle" colspan="1" class="label maxtd" align="center">XXX</td><td valign="middle" colspan="3" class="maxtd value">${XXX}</td></tr><tr><td colspan="1" class="label normaltd" align="center">XXX</td><td colspan="3" class="normaltd value">${XXX}</td></tr><tr><td colspan="1" class="label normaltd" align="center">XXX</td><td colspan="3" class="normaltd value">${XXX}</td></tr><tr><td colspan="1" class="label normaltd" align="center">XXX</td><td colspan="3" class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">XXX</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr><tr><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td><td class="label normaltd" align="center">XXX</td><td class="normaltd value">${XXX}</td></tr></table>
</div>
</body>
</html>

执行就可以看到生成的pdf文件了，文件路径在d:/test1.pdf。