SpringBoot Thymeleaf iText7 生成 PDF（2023/08/29）

文章目录

SpringBoot Thymeleaf iText7 生成 PDF（2023/08/29）
- 1. 前言
- 2. 技术思路
- 3. 实现过程
- 4. 测试

1. 前言

近期在项目种遇到了实时生成复杂 PDF 的需求，经过一番调研和测试，最终选择了采用 Thymeleaf 和 iText7 来实现需求，本文将详细介绍实现过程。

2. 技术思路

通过 Thymeleaf 渲染生成需要的页面内容；
通过 iText7 html2pdf 库将 Thymeleaf 渲染的结果转换成 PDF；
将 PDF 内容写入到接口输出流中返回给前端浏览器展示；

3. 实现过程

Maven 引入依赖；

<!-- Thymeleaf -->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency><!-- iText html2pdf -->
<dependency><groupId>com.itextpdf</groupId><artifactId>html2pdf</artifactId><version>5.0.0</version>
</dependency><!-- lombok -->
<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId>
</dependency><!-- 获取资源文件 -->
<dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.8.21</version>
</dependency>

编写 Thymeleaf 模板 resources/templates/demo.html；

<!DOCTYPE html>
<html lang="zh"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>PDF Demo</title><style>body {padding-top: 50px;padding-left: 60px;padding-right: 60px;font-family: 'KaiTi', serif;}.title {color: red;text-align: center;margin-bottom: 50px;}table {width: 100%;border: 1px solid black;border-spacing: 0;}th {border: 1px solid black;background-color: rgb(128, 128, 128);}td {border: 1px solid black;}</style>
</head><body>
<h1 class="title" th:text="${title}"></h1><table><thead><tr><th>序号</th><th>姓名</th><th>年龄</th><th>性别</th></tr></thead><tbody th:each="student, studentStat : ${students}"><tr><td th:text="${studentStat.count}"></td><td th:text="${student.name}"></td><td th:text="${student.age}"></td><td th:text="${student.sex}"></td></tr></tbody>
</table></body>
</html>

添加中文字体资源 resources/fonts/simkai.ttf；

编写 PDF 页码事件处理 handler/PageEventHandler；

package com.xiaoqqya.itextpdf.handler;import com.itextpdf.kernel.events.Event;
import com.itextpdf.kernel.events.IEventHandler;
import com.itextpdf.kernel.events.PdfDocumentEvent;
import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfPage;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
import com.itextpdf.layout.Canvas;
import com.itextpdf.layout.element.Paragraph;
import com.itextpdf.layout.properties.TextAlignment;/*** 页码事件处理.** @author <a href="mailto:xiaoQQya@126.com">xiaoQQya</a>* @since 2023/08/29*/
public class PageEventHandler implements IEventHandler {@Overridepublic void handleEvent(Event event) {PdfDocumentEvent documentEvent = (PdfDocumentEvent) event;PdfDocument document = documentEvent.getDocument();PdfPage page = documentEvent.getPage();Rectangle pageSize = page.getPageSize();PdfCanvas pdfCanvas = new PdfCanvas(page.getLastContentStream(), page.getResources(), document);Canvas canvas = new Canvas(pdfCanvas, pageSize);float x = (pageSize.getLeft() + pageSize.getRight()) / 2;float y = pageSize.getBottom() + 15;Paragraph paragraph = new Paragraph("-- " + document.getPageNumber(page) + " --").setFontSize(10);canvas.showTextAligned(paragraph, x, y, TextAlignment.CENTER);canvas.close();}
}

编写 Student 实体类 model/domain/Student；

package com.xiaoqqya.itextpdf.model.domain;import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;/*** 学生.** @author <a href="mailto:xiaoQQya@126.com">xiaoQQya</a>* @since 2023/08/29*/
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class Student {/*** 姓名*/private String name;/*** 、* 年龄*/private Integer age;/*** 性别*/private String sex;
}

编写 Service service/PdfService 生成 PDF；

package com.xiaoqqya.itextpdf.service.impl;import cn.hutool.core.io.resource.ResourceUtil;
import com.itextpdf.html2pdf.ConverterProperties;
import com.itextpdf.html2pdf.HtmlConverter;
import com.itextpdf.html2pdf.resolver.font.DefaultFontProvider;
import com.itextpdf.io.font.FontProgramFactory;
import com.itextpdf.kernel.events.PdfDocumentEvent;
import com.itextpdf.kernel.geom.PageSize;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.layout.font.FontProvider;
import com.xiaoqqya.itextpdf.exception.CustomException;
import com.xiaoqqya.itextpdf.handler.PageEventHandler;
import com.xiaoqqya.itextpdf.model.domain.Student;
import com.xiaoqqya.itextpdf.service.PdfService;
import org.springframework.stereotype.Service;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.Context;import javax.annotation.Resource;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;/*** PDF Service.** @author <a href="mailto:xiaoQQya@126.com">xiaoQQya</a>* @since 2023/08/29*/
@Service
public class PdfServiceImpl implements PdfService {@Resourceprivate TemplateEngine templateEngine;/*** 生成 PDF.** @param outputStream 输出流*/@Overridepublic void generatePdf(OutputStream outputStream) {// 模拟数据List<Student> students = new ArrayList<>();students.add(Student.builder().name("小红").age(18).sex("女").build());students.add(Student.builder().name("小强").age(21).sex("男").build());students.add(Student.builder().name("熊大").age(19).sex("男").build());// 生成 Thymeleaf 上下文Context context = new Context();context.setVariable("title", "PDF Demo");context.setVariable("students", students);String demo = templateEngine.process("demo", context);// 生成 PDF, 并添加页码try (PdfWriter pdfWriter = new PdfWriter(outputStream); PdfDocument pdfDocument = new PdfDocument(pdfWriter)) {pdfDocument.setDefaultPageSize(PageSize.A4);pdfDocument.addEventHandler(PdfDocumentEvent.INSERT_PAGE, new PageEventHandler());ConverterProperties converterProperties = new ConverterProperties();FontProvider fontProvider = new DefaultFontProvider(true, true, false);fontProvider.addFont(FontProgramFactory.createFont(ResourceUtil.readBytes("fonts/simkai.ttf")));converterProperties.setFontProvider(fontProvider);HtmlConverter.convertToPdf(demo, pdfDocument, converterProperties);} catch (IOException e) {throw new CustomException(e.getMessage());}}
}

编写 Controller controller/PdfController 返回给前端浏览器展示；

package com.xiaoqqya.itextpdf.controller;import com.xiaoqqya.itextpdf.service.PdfService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;/*** PDF Controller.** @author <a href="mailto:xiaoQQya@126.com">xiaoQQya</a>* @since 2023/08/29*/
@RestController
@RequestMapping(value = "/pdf")
public class PdfController {@Resourceprivate PdfService pdfService;/*** 生成 PDF.*/@GetMappingpublic void generatePdf(HttpServletResponse response) throws IOException {pdfService.generatePdf(response.getOutputStream());}
}