SpringBoot Thymeleaf iText7 生成 PDF（2023/08/29）-Toy模板网

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

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 {

    @Override
    public 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 {

    @Resource
    private TemplateEngine templateEngine;

    /**
     * 生成 PDF.
     *
     * @param outputStream 输出流
     */
    @Override
    public 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 {

    @Resource
    private PdfService pdfService;

    /**
     * 生成 PDF.
     */
    @GetMapping
    public void generatePdf(HttpServletResponse response) throws IOException {
        pdfService.generatePdf(response.getOutputStream());
    }
}