java实现pdf浏览器预览功能

11月 6, 2022 192点热度 2人点赞 0条评论

最近在做项目,有个需求为根据订单的详情生成pdf并能够支持pdf的预览功能。为了能够简单的实现功能,就使用了浏览器自带的预览pdf功能实现。

环境准备

具体的环境如下:

  • jdk 8
  • maven 3.6.3
  • idea

pom 依赖

为了能够快速的启动项目,则使用spring-boot作为依赖,则对应的pom文件如下:

<properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.3.3.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>

        <dependency>
            <groupId>org.xhtmlrenderer</groupId>
            <artifactId>flying-saucer-pdf-openpdf</artifactId>
            <version>9.1.20</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
        </dependency>

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-core</artifactId>
            <version>5.8.9</version>
        </dependency>
    </dependencies>

相关配置

在实例中主要使用了以下框架:

  • freemarker用于生成html文本
  • flying-saucer-pdf-openpdf 用于生成pdf文档

freemarker

freemarker主要配置了模板的路径信息,主要配置如下:

spring:
  freemarker:
    enabled: true
    template-loader-path: classpath:/templates/

在对应的订单详情生成模板:

<html>
<head>
    <title>${title}</title>
    <style>
        body {
            MARGIN: AUTO;
            width: 690px;
            font-size: 12px;
            font-family: SimSun;
            color: #222;
        }
    </style>
</head>
<body>
<table>
    <tbody>
    <tr>
        <td>订单编号:</td>
        <td>${orderNo}</td>
        <td>订单时间:</td>
        <td>${orderDate}</td>
    </tr>
    <tr>
        <td>收货地址:</td>
        <td>${address}</td>
        <td>联系人:</td>
        <td>${userName}</td>
    </tr>
    </tbody>
</table>
</body>
</html>

业务逻辑

业务实体Order

order中主要定义了订单相关信息,

package org.spring.learn.pdf.entity;

import lombok.Builder;
import lombok.Data;

@Data
@Builder
public class Order {

    private String orderNo;
    private String title;
    private String userName;
    private String address;
    private String orderDate;
}

业务逻辑

业务逻辑主要根据订单相关信息填充模板,并生成html, 并根据html生成对应的pdf信息,则对应业务代码如下;

package org.spring.learn.pdf.service;

import cn.hutool.core.date.DateUtil;
import cn.hutool.core.lang.UUID;
import com.lowagie.text.pdf.BaseFont;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.spring.learn.pdf.entity.Order;
import org.spring.learn.pdf.util.StreamUtil;
import org.springframework.stereotype.Service;
import org.xhtmlrenderer.layout.SharedContext;
import org.xhtmlrenderer.pdf.ITextFontResolver;
import org.xhtmlrenderer.pdf.ITextRenderer;

import java.io.*;
import java.util.Date;

@Service
public class OrderService {

    public static final String ORDER_TPL = "order.ftl";

    private Configuration configuration;

    public OrderService(Configuration configuration) {
        this.configuration = configuration;
    }

    public File previewPdf(String orderNo) throws IOException, TemplateException {
        // 模拟创建订单
        Order order = Order.builder()
                .orderDate(DateUtil.formatDate(new Date()))
                .orderNo(orderNo)
                .title("订单: " + orderNo)
                .address("收货地址")
                .userName("测试用户")
                .build();

        // 写出pdf到临时文件
        String pathPrefix = OrderService.class.getResource("/").getPath();
        String filePath = pathPrefix + File.separator + "/temp/" + UUID.randomUUID().toString() + ".pdf";
        File file = new File(filePath);

        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
        }

        FileOutputStream fios = new FileOutputStream(file);

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        Template template = configuration.getTemplate(ORDER_TPL);
        template.process(order, new OutputStreamWriter(baos));

        // 获取html信息
        String htmlStr = new String(baos.toByteArray());

        // 将html转转为pdf
        ITextRenderer iTextRenderer = new ITextRenderer();

        SharedContext sharedContext = iTextRenderer.getSharedContext();
        sharedContext.setPrint(true);
        sharedContext.setInteractive(false);

        ITextFontResolver fontResolver = iTextRenderer.getFontResolver();
        String fontPath = OrderService.class.getResource("/simsun.ttc").getPath();
        fontResolver.addFont(fontPath, BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);

        iTextRenderer.setDocumentFromString(htmlStr);
        iTextRenderer.layout();
        // 写出
        iTextRenderer.createPDF(fios);

        StreamUtil.close(fios);
        return file;
    }
}

Controller实现

Controller主要接收请求,写出数据,则对应代码如下:

package org.spring.learn.pdf.controller;

import lombok.extern.slf4j.Slf4j;
import org.spring.learn.pdf.service.OrderService;
import org.spring.learn.pdf.util.StreamUtil;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;

@Slf4j
@RestController
@RequestMapping("/order")
public class OrderPdfPreviewController {

    private OrderService orderService;

    public OrderPdfPreviewController(OrderService orderService) {
        this.orderService = orderService;
    }

    @GetMapping("/pdf/preview/{orderNo}")
    public void previewPdf(@PathVariable("orderNo") String orderNo, HttpServletResponse response) {
        FileInputStream fis = null;
        try {
            File f = orderService.previewPdf(orderNo);

            response.setContentType("application/pdf");
            // 获取文件输入流
            fis = new FileInputStream(f);
            FileChannel fileChannel = fis.getChannel();
            fileChannel.transferTo(0, fileChannel.size(), Channels.newChannel(response.getOutputStream()));
        } catch (Exception e) {
            log.error("previewPdf: 预览pdf失败, 原因: {}", e.getMessage(), e);
        } finally {
            StreamUtil.close(fis);
        }
    }
}

启动类

spring-boot启动类如下:

package org.spring.learn.pdf;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class PdfApplication {

    public static void main(String[] args) {
        SpringApplication.run(PdfApplication.class, args);
    }
}

我们启动后端的服务,并访问http://localhost:8080/order/pdf/preview/234, 则可以看到浏览器打开了pdf文档,如图:

则pdf对应的预览功能实现。

问题

1.如何控制PDF分页

当我们希望单个订单单独显示为一个PDF页的时候,由于每个订单的长度不一致,所以需要控制PDF分页信息,这时,我们可以只修改html的样式接口实现,例如:

<html>
<head>
    <title>${title}</title>
    <style>
        body {
            MARGIN: AUTO;
            width: 690px;
            font-size: 12px;
            font-family: SimSun;
            color: #222;
        }
       .pdfpage {
            width: 100%;
            page-break-inside: avoid;
        }
    </style>
</head>
<body>
<#list orders as order>
<table class="pdfpage">
    <tbody>
    <tr>
        <td>订单编号:</td>
        <td>${order.orderNo}</td>
        <td>订单时间:</td>
        <td>${order.orderDate}</td>
    </tr>
    <tr>
        <td>收货地址:</td>
        <td>${order.address}</td>
        <td>联系人:</td>
        <td>${order.userName}</td>
    </tr>
    </tbody>
</table>
</#list>
</body>
</html>

主要通过page-break-inside控制分页的参数信息,问题的到解决。

2.设置PDF页方向

有时我们生成的PDF因为内容比较长,可能会导致部分内容被截取,这个时候我们可以设置PDF的页为横向,展示超过的部分内容。只需要在html中加入@page样式即可

/*横向*/
@page{
size: 297mm 210mm;
}

/*纵向*/
@page {
size: 210mm 297mm;
}

 

3. 默认生成pdf中文不展示

这个是因为flying-saucer-pdf-openpdf默认不支持中文,需要我们用自己的字体替代,我们可以在C:/windows/fonts中选择宋体,并拷贝到项目的resources中,则可以通过代码的方式加入的框架,并在html中使用字体即可。

在代码中可以加入如下代码:

ITextFontResolver fontResolver = iTextRenderer.getFontResolver();
        String fontPath = OrderService.class.getResource("/simsun.ttc").getPath();
        fontResolver.addFont(fontPath, BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);

在html模板中使用引入的字体,字体需要区分大小写:

<style>
        body {
            MARGIN: AUTO;
            width: 690px;
            font-size: 12px;
            font-family: SimSun;
            color: #222;
        }
    </style>

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