出于某些需求需要将一张简单的图片转换为PDF的文件格式，因此自己动手写了一个图片转换PDF的系统，现在将该系统分享在这里，供大家参考。

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具体代码：

引入依赖：

    org.springframework.boot
    spring-boot-starter-parent
    2.0.4.RELEASE
    



	
    
        org.springframework.boot
        spring-boot-starter-web
    
    
    
        com.itextpdf
        itextpdf
        5.4.2
    

前端页面：

    
    
    


    

        
图片转换pdf工具
        

            

            
        
    

（推荐教程：java入门教程）

控制层接口

package com.hrp.controller;

import com.hrp.util.PdfUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;

/**
 * @description: 用于处理Pdf相关的请求
 */
@Controller
@RequestMapping("pdf")
public class PdfController {

    @PostMapping("image/to")
    public void imageToPdf(@RequestParam("file") MultipartFile file,HttpServletResponse response) throws Exception{
        PdfUtils.imageToPdf(file,response);
    }

}

PDF工具类

package com.hrp.util;

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.pdf.PdfWriter;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;


/**
 * @description: pdf相关的工具类
 */
@Component
public class PdfUtils {

    /**
     * 图片转换PDF的公共接口
     *
     * @param file     SpringMVC获取的图片文件
     * @param response HttpServletResponse
     * @throws IOException       IO异常
     * @throws DocumentException PDF文档异常
     */
    public static void imageToPdf(MultipartFile file, HttpServletResponse response) throws IOException, DocumentException {
        File pdfFile = generatePdfFile(file);
        downloadPdfFile(pdfFile, response);
    }

    /**
     * 将图片转换为PDF文件
     *
     * @param file SpringMVC获取的图片文件
     * @return PDF文件
     * @throws IOException       IO异常
     * @throws DocumentException PDF文档异常
     */
    private static File generatePdfFile(MultipartFile file) throws IOException, DocumentException {
        String fileName = file.getOriginalFilename();
        String pdfFileName = fileName.substring(0, fileName.lastIndexOf(".")) + ".pdf";
        Document doc = new Document(PageSize.A4, 20, 20, 20, 20);
        PdfWriter.getInstance(doc, new FileOutputStream(pdfFileName));
        doc.open();
        doc.newPage();
        Image image = Image.getInstance(file.getBytes());
        float height = image.getHeight();
        float width = image.getWidth();
        int percent = getPercent(height, width);
        image.setAlignment(Image.MIDDLE);
        image.scalePercent(percent);
        doc.add(image);
        doc.close();
        File pdfFile = new File(pdfFileName);
        return pdfFile;
    }

    /**
     *
     * 用于下载PDF文件
     *
     * @param pdfFile  PDF文件
     * @param response HttpServletResponse
     * @throws IOException IO异常
     */
    private static void downloadPdfFile(File pdfFile, HttpServletResponse response) throws IOException {
        FileInputStream fis = new FileInputStream(pdfFile);
        byte[] bytes = new byte[fis.available()];
        fis.read(bytes);
        fis.close();

        response.reset();
        response.setHeader("Content-Type", "application/pdf");
        response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(pdfFile.getName(), "UTF-8"));
        OutputStream out = response.getOutputStream();
        out.write(bytes);
        out.flush();
        out.close();
    }


    /**
     * 等比压缩，获取压缩百分比
     *
     * @param height 图片的高度
     * @param weight 图片的宽度
     * @return 压缩百分比
     */
    private static int getPercent(float height, float weight) {
        float percent = 0.0F;
        if (height > weight) {
            percent = PageSize.A4.getHeight() / height * 100;
        } else {
            percent = PageSize.A4.getWidth() / weight * 100;
        }
        return Math.round(percent);
    }
}

实现效果：