java 富文本转pdf
前言：
本文的目的是将传入的富文本内容(html标签，图片)并且分页导出为pdf。
所用的核心依赖为iText7。
因为itextpdf-core的核心包在maven中央仓库中，阿里云华为云等拉不下来，中央仓库在外网，并且此包在中央仓库中未提供可下载的jar包文件，所以通过iText github上提供的core包的组成jar，实现core包所需方法的调用。
一、jar包导入
在子项目的resources下新建lib目录，下载文件所提供的压缩包，解压jar包文件到lib下，如图所示
二、maven依赖导入
<dependency><groupId>com.itextpdf</groupId><artifactId>barcodes</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/barcodes-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>commons</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/commons-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>font-asian</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/font-asian-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>forms</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/forms-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>hyph</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/hyph-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>io</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/io-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>kernel</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/kernel-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>layout</artifactId><version>7.2.3</version> <!-- 如果需要布局功能 --><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/layout-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>pdfa</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/pdfa-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>pdftest</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/pdftest-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>sign</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/sign-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>styled-xml-parser</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/styled-xml-parser-7.2.3.jar</systemPath></dependency><dependency><groupId>com.itextpdf</groupId><artifactId>svg</artifactId><version>7.2.3</version><scope>system</scope><systemPath>${project.basedir}/src/main/resources/lib/svg-7.2.3.jar</systemPath></dependency><!-- https://mvnrepository.com/artifact/com.itextpdf/html2pdf --><dependency><groupId>com.itextpdf</groupId><artifactId>html2pdf</artifactId><version>4.0.3</version></dependency>三、打包配置
因为从外部引入jar包，在本地测试没有问题，但是打包后发布，引用不了，所以需要配置打包引用外部jar包。所以可以根据以下链接，博主的另外一个文章提供了相关的方法。
java引用第三方jar包，打包全流程_java引入外部jar包-CSDN博客
四、工具类
import com.itextpdf.html2pdf.ConverterProperties;
import com.itextpdf.html2pdf.HtmlConverter;
import com.itextpdf.html2pdf.resolver.font.DefaultFontProvider;
import com.itextpdf.io.exceptions.IOException;
import com.itextpdf.layout.font.FontProvider;
import org.springframework.stereotype.Component;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;@Component
public class RichTextExporter {/*** HTML内容转PDF并输出到响应流* @param htmlContent HTML内容* @param response HttpServletResponse* @param request HttpServletRequest（用于获取基础路径）* @param fileName 生成的PDF文件名* @throws IOException 转换过程异常*/public static void convertToPdf(String htmlContent,HttpServletResponse response,HttpServletRequest request,String fileName) throws IOException, java.io.IOException {// 配置响应头configureResponseHeaders(response, fileName, request);try (OutputStream outputStream = response.getOutputStream()) {// 创建转换器配置ConverterProperties converterProperties = createConverterProperties(request);// 执行转换HtmlConverter.convertToPdf(htmlContent, outputStream, converterProperties);}}/*** 配置HTTP响应头*/private static void configureResponseHeaders(HttpServletResponse response,String fileName,HttpServletRequest request) {response.setContentType("application/pdf");String attachment = String.format("attachment; filename=\"%s\"",encodeFileName(fileName, request));response.setHeader("Content-Disposition", attachment);response.setCharacterEncoding(StandardCharsets.UTF_8.name());}/*** 创建转换器配置（处理路径、字体、字符集等）*/private static ConverterProperties createConverterProperties(HttpServletRequest request) {ConverterProperties properties = new ConverterProperties();// 设置基础URI（解析相对路径，如图片/字体地址）properties.setBaseUri(getBaseHttpPath(request));// 配置字体（支持中文、非嵌入字体、符号）FontProvider fontProvider = new DefaultFontProvider(true, true, true);properties.setFontProvider(fontProvider);// 设置字符集properties.setCharset(StandardCharsets.UTF_8.name());return properties;}/*** 获取完整的基础HTTP路径（包含协议、域名、端口、上下文路径）*/private static String getBaseHttpPath(HttpServletRequest request) {int port = request.getServerPort();String portStr = (port == 80 || port == 443) ? "" : ":" + port;return String.format("%s://%s%s%s",request.getScheme(),request.getServerName(),portStr,request.getContextPath());}/*** 处理文件名编码（兼容不同浏览器）*/private static String encodeFileName(String fileName, HttpServletRequest request) {String userAgent = request.getHeader("User-Agent");try {if (userAgent.contains("MSIE") || userAgent.contains("Edge") || userAgent.contains("Chrome")) {return java.net.URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");} else {return new String(fileName.getBytes(StandardCharsets.UTF_8), "ISO-8859-1");}} catch (Exception e) {return fileName;}}}五、controller
@PostMapping("/export")@Operation(summary = "导出pdf")@Parameter(name = "htmlContent", description = "富文本内容", required = true)public void exportPdf(@RequestParam("htmlContent") String htmlContent, HttpServletRequest request, HttpServletResponse response) throws IOException {RichTextExporter.convertToPdf(htmlContent, response, request, "pdf导出测试");}六、yaml配置
因为富文本内容很大，所以如果必须用post请求，并且需要修改上传配置，在yaml文件中加入如下配置即可：
###设置缓冲区大小，方便上传大文件
server:tomcat:max-swallow-size: 15MBmax-http-form-post-size: 16777216七、测试
八、注意
经测试，富文本内容最好把ol标签给过滤掉，因为会导致富文本导出为pdf出错，并且如果还需要支持其余特殊的标签，请自行扩展工具类。