如何利用java实现生成PDF文件

2022-11-13 18:11:34 文件生成利用

1.PDF文件简介

PDF是可移植文档格式，是一种电子文件格式，具有许多其他电子文档格式无法相比的优点。PDF文件格式可以将文字、字型、格式、颜色及独立于设备和分辨率的图形图像等封装在一个文件中。该格式文件还可以包含超文本链接、声音和动态影像等电子信息，支持特长文件，集成度和安全可靠性都较高。在系统开发中通常用来生成比较正式的报告或者合同类的电子文档。

2.生成PDF

2.1 基于freemarker框架实现HTML转PDF

2.1.1 引入jar包依赖:

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.20</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.itextpdf/html2pdf -->
<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>html2pdf</artifactId>
    <version>4.0.3</version>
</dependency>
<!-- Spring Boot 项目请添加此依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>
<!-- 非spring boot 项目请添加此依赖 -->
<dependency>
    <groupId>org.freemarker</groupId>
    <artifactId>freemarker</artifactId>
    <version>2.3.30</version>
</dependency>

2.1.2 创建html模板test_template：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8"/>
    <title>Title</title>
    <style>
        body{font-family:SimSun;}
        .title{align-content: center;text-align: center;}
        .signature{float:right }
    </style>
</head>
<body>
<div>
    <h1 class="title">标题</h1>
    <h4 class="title">副标题</h4>
    <span>当前时间: ${date_time} </span>
    <div class="signature">日期：${date}</div>
</div>
</body>
</html>

2.1.3 获取HTML内容

当HTML模板存放在系统文件夹

String templateDirectory = "D:\\";  // 系统文件夹路径 如: D:\

当HTML模板存放在项目resources/templates目录

ClassLoader classLoader = PdfUtilTest.class.getClassLoader();
URL resource = classLoader.getResource("templates");
String templateDirectory = resource.toURI().getPath();

示例代码:

import com.itextpdf.html2pdf.ConverterProperties;
import com.itextpdf.html2pdf.HtmlConverter;
import com.itextpdf.layout.font.FontProvider;
import freemarker.template.Configuration;
import freemarker.template.Template;
import lombok.extern.slf4j.Slf4j;

import java.io.*;
import java.net.URL;
import java.time.LocalDateTime;
import java.time.fORMat.DateTimeFormatter;
import java.util.HashMap;
import java.util.Map;

@Slf4j
public class PdfUtilTest {
    
    private static String getTemplateContent(String templateDirectory, String templateName, Map<String, Object> paramMap) throws Exception {
        Configuration configuration = new Configuration(Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS);
        try {
            configuration.setDirectoryForTemplateLoading(new File(templateDirectory));
        } catch (Exception e) {
            System.out.println("-- exception --");
        }

        Writer out = new StringWriter();
        Template template = configuration.getTemplate(templateName,"UTF-8");
        template.process(paramMap, out);
        out.flush();
        out.close();
        return out.toString();
    }
    public static void main(String[] args) throws Exception {
        Map<String, Object> paramMap = new HashMap<>();
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        paramMap.put("date_time", dateTimeFormatter.format(LocalDateTime.now()));
        paramMap.put("date", dateTimeFormatter.format(LocalDateTime.now()).substring(0, 10));
        ClassLoader classLoader = PdfUtilTest.class.getClassLoader();
        URL resource = classLoader.getResource("templates");
        String templateDirectory  =resource.toURI().getPath();
        String templateContent = PdfUtilTest.getTemplateContent(templateDirectory, "test_template.html", paramMap);
        System.out.println(templateContent);
    }
}

2.1.4 生成PDF文档

示例代码:

    
    public static boolean html2Pdf(String content, String outPath) {
        try {
            ConverterProperties converterProperties = new ConverterProperties();
            converterProperties.setCharset("UTF-8");
            FontProvider fontProvider = new FontProvider();
            fontProvider.addSystemFonts();
            converterProperties.setFontProvider(fontProvider);
            HtmlConverter.convertToPdf(content, new FileOutputStream(outPath), converterProperties);
        } catch (Exception e) {
            log.error("生成模板内容失败,{}",e);
            return false;
        }
        return true;
    }
    
    public static byte[] html2Pdf(String content) {
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();;
        try {
            ConverterProperties converterProperties = new ConverterProperties();
            converterProperties.setCharset("UTF-8");
            FontProvider fontProvider = new FontProvider();
            fontProvider.addSystemFonts();
            converterProperties.setFontProvider(fontProvider);
            HtmlConverter.convertToPdf(content,outputStream,converterProperties);
        } catch (Exception e) {
            log.error("生成 PDF 失败,{}",e);
        }
        return outputStream.toByteArray();
    }
	public static void main(String[] args) throws Exception {
	    Map<String, Object> paramMap = new HashMap<>();
	    DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
	    paramMap.put("date_time", dateTimeFormatter.format(LocalDateTime.now()));
	    paramMap.put("date", dateTimeFormatter.format(LocalDateTime.now()).substring(0, 10));
	    String outPath = "D:\\A.pdf";
	    String templateDirectory = "D:\\";
	    String templateContent = PdfUtilTest.getTemplateContent(templateDirectory, "test_template.html", paramMap);
	    PdfUtilTest.html2Pdf(templateContent, outPath);
	    
	}

总结

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