一、文档类型介绍

1、Excel文档

Excel一款电子表格软件。直观的界面、出色的计算功能和图表工具，在系统开发中，经常用来把数据转存到Excel文件，或者Excel数据导入系统中，这就涉及数据转换问题。

2、PDF文档

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。

二、Excel文件管理

1、POI依赖

Apache POI是Apache软件基金会的开源类库，POI提供API给Java程序对Microsoft Office格式档案读和写的功能。

github: https://github.com/apache/poi

<!-- Excel 依赖 -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>3.9</version>
</dependency>
<!-- 2007及更高版本 -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>3.9</version>
</dependency>

2、文件读取

public static List<List<Object>> readExcel(String path) throws Exception {
    File file = new File(path) ;
    List<List<Object>> list = new LinkedList<>();
    XSSFWorkbook xwb = new XSSFWorkbook(new FileInputStream(file));
    // 读取 Sheet1 表格内容
    XSSFSheet sheet = xwb.getSheetAt(0);
    // 读取行数：不读取Excel表头
    for (int i = (sheet.getFirstRowNum()+1); i <= (sheet.getPhysicalNumberOfRows()-1); i++) {
        XSSFRow row = sheet.getRow(i);
        if (row == null) { continue; }
        List<Object> linked = new LinkedList<>();
        for (int j = row.getFirstCellNum(); j <= row.getLastCellNum(); j++) {
            XSSFCell cell = row.getCell(j);
            if (cell == null) { continue; }
            Object value ;
            // 这里需根据实际业务情况处理
            switch (cell.getCellType()) {
                case XSSFCell.CELL_TYPE_NUMERIC:
                    //处理数值带{.0}问题
                    value = Double.valueOf(String.valueOf(cell)).longValue() ;
                    break;
                default:
                    value = cell.toString();
            }
            linked.add(value);
        }
        if (linked.size()!= 0) {
            list.add(linked);
        }
    }
    return list;
}

3、文件创建

public static void createExcel(String excelName, String[] headList,List<List<Object>> dataList)
        throws Exception {
    // 创建 Excel 工作簿
    XSSFWorkbook workbook = new XSSFWorkbook();
    XSSFSheet sheet = workbook.createSheet();
    // 创建表头
    XSSFRow row = sheet.createRow(0);
    for (int i = 0; i < headList.length; i++) {
        XSSFCell cell = row.createCell(i);
        cell.setCellType(XSSFCell.CELL_TYPE_STRING);
        cell.setCellValue(headList[i]);
    }
    //添加数据
    for (int line = 0; line < dataList.size(); line++) {
        XSSFRow rowData = sheet.createRow(line+1);
        List<Object> data = dataList.get(line);
        for (int j = 0; j < headList.length; j++) {
            XSSFCell cell = rowData.createCell(j);
            cell.setCellType(XSSFCell.CELL_TYPE_STRING);
            cell.setCellValue((data.get(j)).toString());
        }
    }
    FileOutputStream fos = new FileOutputStream(excelName);
    workbook.write(fos);
    fos.flush();
    fos.close();
}

4、文件导出

public static void exportExcel(String[] headList, List<List<Object>> dataList,
                               OutputStream outputStream) throws Exception {
    // 创建 Excel 工作簿
    XSSFWorkbook workbook = new XSSFWorkbook();
    XSSFSheet sheet = workbook.createSheet();
    // 创建表头
    XSSFRow row = sheet.createRow(0);
    for (int i = 0; i < headList.length; i++) {
        XSSFCell cell = row.createCell(i);
        cell.setCellType(XSSFCell.CELL_TYPE_STRING);
        cell.setCellValue(headList[i]);
    }
    //添加数据
    for (int line = 0; line < dataList.size(); line++) {
        XSSFRow rowData = sheet.createRow(line+1);
        List<Object> data = dataList.get(line);
        for (int j = 0; j < headList.length; j++) {
            XSSFCell cell = rowData.createCell(j);
            cell.setCellType(XSSFCell.CELL_TYPE_STRING);
            cell.setCellValue((data.get(j)).toString());
        }
    }
    workbook.write(outputStream);
    outputStream.flush();
    outputStream.close();
}

5、文件导出接口

@RestController
public class ExcelDownLoadWeb {
    @RequestMapping("/file/outExcel")
    public void outExcel (HttpServletResponse response) throws Exception {
        String exportName = "2023-05-BSDATA" ;
        response.setContentType("application/vnd.ms-excel");
        response.addHeader("Content-Disposition", "attachment;filename="+
                             URLEncoder.encode(exportName, "UTF-8") + ".xlsx");
        List<List<Object>> dataList = ExcelUtil.readExcel("F:\\file-type\\user-excel.xlsx") ;
        String[] headList = new String[]{"测站", "时间", "降雨量"} ;
        ExcelUtil.exportExcel(headList,dataList,response.getOutputStream()) ;
    }
}

三、PDF文件管理

1、IText依赖

iText是一种生成PDF报表的Java组件。通过在服务器端使用页面或API封装生成PDF报表，客户端可以通过超链接直接显示或下载到本地，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。

github: https://github.com/itext/itextpdf

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itextpdf</artifactId>
    <version>5.5.11</version>
</dependency>
<dependency>
    <groupId>com.itextpdf.tool</groupId>
    <artifactId>xmlworker</artifactId>
    <version>5.5.11</version>
</dependency>

2、API二次封装

首先对于Itext提供的API做一下表格、段落、图片等基础样式的二次封装，可以更好的适配业务。

public class PdfFontUtil {
    private PdfFontUtil(){}

    /**
     * 段落样式获取
     */
    public static Paragraph getParagraph (String content, Font font,Integer alignment){
        Paragraph paragraph = new Paragraph(content,font) ;
        if (alignment != null && alignment >= 0){
            paragraph.setAlignment(alignment);
        }
        return paragraph ;
    }
    /**
     * 图片样式
     */
    public static Image getImage (String imgPath,float width,float height) throws Exception {
        Image image = Image.getInstance(imgPath);
        image.setAlignment(Image.MIDDLE);
        if (width > 0 && height > 0){
            image.scaleAbsolute(width, height);
        }
        return image ;
    }
    /**
     * 表格生成
     */
    public static PdfPTable getPdfPTable01 (int numColumns,float totalWidth) throws Exception {
        // 表格处理
        PdfPTable table = new PdfPTable(numColumns);
        // 设置表格宽度比例为%100
        table.setWidthPercentage(100);
        // 设置宽度:宽度平均
        table.setTotalWidth(totalWidth);
        // 锁住宽度
        table.setLockedWidth(true);
        // 设置表格上面空白宽度
        table.setSpacingBefore(10f);
        // 设置表格下面空白宽度
        table.setSpacingAfter(10f);
        // 设置表格默认为无边框
        table.getDefaultCell().setBorder(0);
        table.setPaddingTop(50);
        table.setSplitLate(false);
        return table ;
    }
    /**
     * 表格内容
     */
    public static PdfPCell getPdfPCell (Phrase phrase){
        return new PdfPCell (phrase) ;
    }
    /**
     * 表格内容带样式
     */
    public static void addTableCell (PdfPTable dataTable,Font font,List<String> cellList){
        for (String content:cellList) {
            dataTable.addCell(getParagraph(content,font,-1));
        }
    }
}

3、生成PDF文件

这里基于上面的工具类，画一个PDF页面作为参考。

public class PdfPagetTest {
    // 基础配置
    private static String PDF_SITE = "E:\\temp\\PDF页面2023-04-15.pdf" ;
    private static String FONT = "C:/Windows/Fonts/simhei.ttf";
    private static String PAGE_TITLE = "PDF" ;
    // 基础样式
    private static Font TITLE_FONT = FontFactory.getFont(FONT, BaseFont.IDENTITY_H,20, Font.BOLD);
    private static Font NODE_FONT = FontFactory.getFont(FONT, BaseFont.IDENTITY_H,15, Font.BOLD);
    private static Font BLOCK_FONT = FontFactory.getFont(FONT, BaseFont.IDENTITY_H,13, Font.BOLD, BaseColor.BLACK);
    private static Font INFO_FONT = FontFactory.getFont(FONT, BaseFont.IDENTITY_H,12, Font.NORMAL,BaseColor.BLACK);
    private static Font CONTENT_FONT = FontFactory.getFont(FONT, BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);

    private static void createPdfPage () throws Exception {
        // 创建文档
        Document document = new Document();
        PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(PDF_SITE));
        document.open();
        // 报告标题
        document.add(PdfFontUtil.getParagraph(PAGE_TITLE,TITLE_FONT,1)) ;
        document.add(PdfFontUtil.getParagraph("\n商户名称：XXX科技有限公司",INFO_FONT,-1)) ;
        document.add(PdfFontUtil.getParagraph("\n生成时间：2020-01-15\n\n",INFO_FONT,-1)) ;
        // 报告内容
        // 段落标题 + 报表图
        document.add(PdfFontUtil.getParagraph("城市数据分布统计",NODE_FONT,-1)) ;
        document.add(PdfFontUtil.getParagraph("\n· 可视化图表\n\n",BLOCK_FONT,-1)) ;
        // 设置图片宽高
        float documentWidth = document.getPageSize().getWidth() - document.leftMargin() - document.rightMargin();
        float documentHeight = documentWidth / 580 * 320;
        document.add(PdfFontUtil.getImage("F:\\file-type\\myChart.jpg",documentWidth-80,documentHeight-80)) ;
        // 数据表格
        document.add(PdfFontUtil.getParagraph("\n· 数据详情\n\n",BLOCK_FONT,-1)) ;
        PdfPTable dataTable = PdfFontUtil.getPdfPTable01(4,400) ;
        // 设置表格
        List<String> tableHeadList = tableHead () ;
        List<List<String>> tableDataList = getTableData () ;
        PdfFontUtil.addTableCell(dataTable,CONTENT_FONT,tableHeadList);
        for (List<String> tableData : tableDataList) {
            PdfFontUtil.addTableCell(dataTable,CONTENT_FONT,tableData);
        }
        document.add(dataTable);
        document.add(PdfFontUtil.getParagraph("\n· 报表描述\n\n",BLOCK_FONT,-1)) ;
        document.add(PdfFontUtil.getParagraph("数据报告可以监控每天的推广情况，" +
                "可以针对不同的数据表现进行分析，以提升推广效果。",CONTENT_FONT,-1)) ;
        document.newPage() ;
        document.close();
        writer.close();
    }
    private static List<List<String>> getTableData (){
        List<List<String>> tableDataList = new ArrayList<>() ;
        for (int i = 0 ; i < 3 ; i++){
            List<String> tableData = new ArrayList<>() ;
            tableData.add("浙江"+i) ;
            tableData.add("杭州"+i) ;
            tableData.add("276"+i) ;
            tableData.add("33.3%") ;
            tableDataList.add(tableData) ;
        }
        return tableDataList ;
    }
    private static List<String> tableHead (){
        List<String> tableHeadList = new ArrayList<>() ;
        tableHeadList.add("省份") ;
        tableHeadList.add("城市") ;
        tableHeadList.add("数量") ;
        tableHeadList.add("百分比") ;
        return tableHeadList ;
    }
    public static void main(String[] args) throws Exception {
        createPdfPage () ;
    }
}

4、页面效果

四、网页转PDF

1、页面Jar包依赖

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

2、编写页面样式

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8"/>
    <title>Title</title>
    <style>
        body{font-family:SimSun;}
    </style>
</head>
<body>
项目信息：<br/>
名称：${name}<br/>
作者：${author}<br/><br/>
<img 
src="https://oscimg.oschina.net/oscnet/up-612b9330a67ba747846b0e0890e4906678b.png"/>
<br/>
</body>
</html>

3、核心配置类

public class PageConfig {
    private static final String DEST = "F:\\file-type\\HTML页面2020-01-15.pdf";
    private static final String HTML = "/pdf_page_one.html";
    private static final String FONT = "C:/Windows/Fonts/simsun.ttc";
    private static Configuration freemarkerCfg = null ;
    static {
        freemarkerCfg = new Configuration(Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS);
        //freemarker的模板目录
        try {
            String path = "TODO:模板路径{自定义}" ;
            freemarkerCfg.setDirectoryForTemplateLoading(new File(path));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 创建文档
     */
    private static void createPdf(String content,String dest) throws Exception {
        Document document = new Document();
        PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(dest));
        document.open();
        XMLWorkerFontProvider fontImp = new XMLWorkerFontProvider(XMLWorkerFontProvider.DONTLOOKFORFONTS);
        fontImp.register(FONT);
        XMLWorkerHelper.getInstance().parseXHtml(writer, document,
                new ByteArrayInputStream(content.getBytes()), null, Charset.forName("UTF-8"), fontImp);
        document.close();
    }
    /**
     * 页面渲染
     */
    private static String freeMarkerRender(Map<String, Object> data, String htmlTmp) throws Exception {
        Writer out = new StringWriter();
        Template template = freemarkerCfg.getTemplate(htmlTmp,"UTF-8");
        template.process(data, out);
        out.flush();
        out.close();
        return out.toString();
    }
    /**
     * 方法入口
     */
    public static void main(String[] args) throws Exception {
        Map<String,Object> data = new HashMap<> ();
        data.put("name","smile");
        data.put("author","知了") ;
        String content = PageConfig.freeMarkerRender(data,HTML);
        PageConfig.createPdf(content,DEST);
    }
}