freemarker自定义模板

模板编程器指南

<dependency><groupId>org.freemarker</groupId><artifactId>freemarker</artifactId><version>2.3.31</version>
</dependency>

freemarker官网参考：
https://freemarker.apache.org/docs/pgui_quickstart_all.html

模板由freemarker.template.template实例表示。通常，您可以使用其从Configuration实例中获取Template实例。getTemplate方法。如果您将示例模板存储在前面集合目录的test.ftlh文件中，则可以执行以下操作：

Template temp=cfg.getTemplate（“test.ftlh”）；

这为您提供了一个Template实例，该实例是通过读取/where/you/store/templates/test.ftlh并对其进行解析而创建的。Template实例以解析后的形式存储模板，而不是以文本形式存储。如果模板丢失或语法不正确，getTemplate将引发异常。
配置缓存模板实例，因此当您下次调用cfg.getTemplate（“test.ftlh”）时，它可能不会再次读取和解析模板文件，只是返回与第一次相同的模板实例。

data-model + template = output

它将数据模型和一个Writer作为参数。它将生成的输出写入Writer

一旦获得了Template实例，就可以无限次地将其与不同的数据模型合并（Template实例是无状态的）。此外，test.ftlh文件仅在创建Template实例时访问，而不是在调用process方法时访问。


@Service
public class TemplateServiceImpl implements TemplateService {// 本地模板文件：resources/freemarker/test.ftlh@Overridepublic String getTemplateContentFromFile(){Configuration cfg = new Configuration(Configuration.VERSION_2_3_31);cfg.setDefaultEncoding("UTF-8");try {ClassPathResource freemarker = new ClassPathResource("freemarker");File file = freemarker.getFile();cfg.setDirectoryForTemplateLoading(file);} catch (IOException e) {e.printStackTrace();}cfg.setSQLDateAndTimeTimeZone(TimeZone.getDefault());StringWriter writer = null;try {Template template = cfg.getTemplate("test.ftlh");Product product = new Product();product.setName("zjy");product.setUrl("www.baidu.com");HashMap<String, Object> map = new HashMap<>();map.put("user", "wwowowow");map.put("latestProduct", product);writer = new StringWriter();template.process(map, writer);} catch (IOException | TemplateException e) {e.printStackTrace();} finally {IOUtils.closeQuietly(writer);}return writer.toString();}@Overridepublic String getTemplateContentFromString(String content, Map<String, Object> dataModal) {if (MapUtil.isEmpty(dataModal)) {return null;}String fileName = dataModal.getOrDefault("fileName", "demo.html").toString();StringReader reader = new StringReader(content);StringWriter writer = null;try {Template template = new Template(fileName, reader, null, "UTF-8");writer = new StringWriter();template.process(dataModal, writer);} catch (IOException e) {e.printStackTrace();} catch (TemplateException e) {e.printStackTrace();} finally {org.apache.commons.io.IOUtils.closeQuietly(writer);}return writer.toString();}
}

// 浏览器下载
@RequestMapping(value = "/text/upload", method = RequestMethod.GET)
@ResponseBody
public HttpServletResponse upload(HttpServletResponse response) {String templateContent = templateService.getTemplateContentFromFile();try (StringReader reader = new StringReader(templateContent);ServletOutputStream output = response.getOutputStream()) {response.reset();// 定义输入文件名String encode = URLEncoder.encode("zjy.html", "UTF-8");response.setHeader("Content-Disposition", "attachment;filename=" + encode);// 定义输出类型
//            response.setContentType("bin");
//            response.setContentType("application/x-msdownload");response.setContentType("application/octet-stream");response.setCharacterEncoding("UTF-8");IOUtils.copy(reader, output, Charset.forName("UTF-8"));} catch (IOException e) {e.printStackTrace();}return response;
}// 下载到本地resources
@RequestMapping(value = "/text/local", method = RequestMethod.GET)
@ResponseBody
public void localDown() {try {String templateContent = templateService.getTemplateContentFromFile();ClassPathResource resource = new ClassPathResource("bak/test.html");File file = resource.getFile();FileUtil.writeUtf8String(templateContent, file);} catch (IOException e) {e.printStackTrace();}}

手动维护模板并生成文件

/*** 编辑器保存的是字符串，* 使用freemarker模板引擎，* 将dataModal数据填充到模板中* 返回完成文件* @param data* @return*/
@RequestMapping(value = "/text/save", method = RequestMethod.POST)
@ResponseBody
public String save(@Nullable @RequestBody String data) {
// 1. 创建datamodal数据Product product = new Product();product.setTemplateFileName("demo.html");product.setName("zjy");product.setUrl("www.baidu.com");HashMap<String, Object> map = new HashMap<>();map.put("user", "wwowowow");map.put("latestProduct", product);// 2. data-model + template = outputString content = templateService.getTemplateContentFromString(data, map);//      字符串模板创建指定文件，如果不存在新建，存在覆盖FileUtil.writeUtf8String(content, "E:\\note\\flowable-project\\liteflow-demo\\liteflow-example\\src\\main\\java\\com\\yomahub\\liteflow\\example\\controller\\demo.html");return content;
}