一、【Spring Boot】 Excel文件导出下载

   Spring Boot Excel 文件导出

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    目标：

           实现Excel文件的直接导出下载，后续开发不需要开发很多代码，直接继承已经写好的代码，增加一个Xml配置就可以直接导出。

    实现：

           1、抽象类 BaseExcelView 继承 webmvc 的 AbstractXlsxStreamingView 抽象类， AbstractXlsxStreamingView 是webmvc继承了最顶层View接口，是可以直接大量数据导出的不会造成内存泄漏问题，即 SXSSFWorkbook 解决了内存问题， 导出只支持xlsx类型文件。

   抽象类代码 BaseExcelView ：

public abstract class BaseExcelView extends AbstractXlsxStreamingView {

    private static final Logger logger = LoggerFactory.getLogger(BaseExcelView.class);

    /**
     * 获取导出文件名
     *
     * @return
     */
    abstract protected String getFileName();

    /**
     * 获取表单名称
     *
     * @return
     */
    abstract protected String getSheetName();

    /**
     * 获取标题栏名称
     *
     * @return
     */
    abstract protected String[] getTitles();

    /**
     * 获取列宽
     *
     * @return
     */
    abstract protected short[] getColumnWidths();

    /**
     * 构造内容单元格
     *
     * @param sheet
     */
    abstract protected void buildContentCells(Sheet sheet);


    @Override
    protected void buildExcelDocument(
            Map<String, Object> model, Workbook workbook, HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        // 构造标题单元格 SXSSFWorkbook
        Sheet sheet = buildTitleCells(workbook);
        // 构造内容单元格
        buildContentCells(sheet);
        // 设置响应头
        setResponseHead(request, response);
    }

    /**
     * 设置响应头
     *
     * @param response
     * @throws IOException
     */
    protected void setResponseHead(HttpServletRequest request,
                                   HttpServletResponse response) throws IOException {
        // 文件名
        String fileName = getFileName();
        String userAgent = request.getHeader("user-agent").toLowerCase();
        logger.info("客户端请求头内容:");
        logger.info("user-agent	值: {}", userAgent);
        if (userAgent != null) {
            if (userAgent.contains("firefox")) {
                // firefox有默认的备用字符集是西欧字符集
                fileName = new String(fileName.getBytes("UTF-8"), "ISO8859-1");
            } else if (userAgent.contains("webkit") && (userAgent.contains("chrome") || userAgent.contains("safari"))) {
                // webkit核心的浏览器,主流的有chrome,safari,360
                fileName = new String(fileName.getBytes("UTF-8"), "ISO8859-1");
            } else {
                // 新老版本的IE都可直接用URL编码工具编码后输出正确的名称,无乱码
                fileName = URLEncoder.encode(fileName, "UTF-8");
            }
        }
        //响应头信息
        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/ms-excel; charset=UTF-8");
        response.setHeader("Content-disposition", "attachment; filename=" + fileName + ".xlsx");
    }

    /**
     * 构造标题单元格
     *
     * @param
     * @return
     */
    protected Sheet buildTitleCells(Workbook workbook) {
        // 表单名称
        String sheetName = getSheetName();
        // 标题名称
        String[] titles = getTitles();
        // 列宽
        short[] colWidths = getColumnWidths();
        // 创建表格
        Sheet sheet = workbook.createSheet(sheetName);
        // 标题单元格样式
        CellStyle titleStyle = getHeadStyle(workbook);
        // 默认内容单元格样式
        CellStyle contentStyle = getBodyStyle(workbook);
        // 标题行
        Row titleRow = sheet.createRow(0);
        // 创建标题行单元格
        for (int i = 0; i < titles.length; i++) {
            // 标题单元格
            Cell cell = titleRow.createCell((short) i);
            cell.setCellType(CellType.STRING);
            cell.setCellValue(new XSSFRichTextString(titles[i]));
            cell.setCellStyle(titleStyle);
            // 设置列宽
            sheet.setColumnWidth((short) i, (short) (colWidths[i] * 256));
            // 设置列默认样式
            sheet.setDefaultColumnStyle((short) i, contentStyle);
        }
        return sheet;
    }


    /**
     * 设置表头的单元格样式
     */
    public CellStyle getHeadStyle(Workbook workbook) {
        // 创建单元格样式
        CellStyle cellStyle = workbook.createCellStyle();
        // 设置单元格的背景颜色为淡蓝色
        cellStyle.setFillForegroundColor(IndexedColors.PALE_BLUE.index);
        // 设置填充字体的样式
        cellStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
        // 设置单元格居中对齐
        cellStyle.setAlignment(HorizontalAlignment.CENTER);
        // 设置单元格垂直居中对齐
        cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        // 创建单元格内容显示不下时自动换行
        cellStyle.setWrapText(true);
        // 设置单元格字体样式
        Font font = workbook.createFont();
        // 字号
        font.setFontHeightInPoints((short) 12);
        // 加粗
        font.setBold(true);
        // 将字体填充到表格中去
        cellStyle.setFont(font);
        // 设置单元格边框为细线条（上下左右）
        cellStyle.setBorderLeft(BorderStyle.THIN);
        cellStyle.setBorderBottom(BorderStyle.THIN);
        cellStyle.setBorderRight(BorderStyle.THIN);
        cellStyle.setBorderTop(BorderStyle.THIN);
        return cellStyle;
    }

    /**
     * 设置表体的单元格样式
     */
    public CellStyle getBodyStyle(Workbook workbook) {
        // 创建单元格样式
        CellStyle cellStyle = workbook.createCellStyle();
        // 设置单元格居中对齐
        cellStyle.setAlignment(HorizontalAlignment.CENTER);
        // 设置单元格居中对齐
        cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        // 创建单元格内容不显示自动换行
        cellStyle.setWrapText(true);
        //设置单元格字体样式字体
        Font font = workbook.createFont();
        // 字号
        font.setFontHeightInPoints((short) 10);
        // 将字体添加到表格中去
        cellStyle.setFont(font);
        // 设置单元格边框为细线条
        cellStyle.setBorderLeft(BorderStyle.THIN);
        cellStyle.setBorderBottom(BorderStyle.THIN);
        cellStyle.setBorderRight(BorderStyle.THIN);
        cellStyle.setBorderTop(BorderStyle.THIN);
        return cellStyle;
    }
}

   Excel导出实现 1: 可以直接继承 BaseExcelView  实现定义的方法 eg:

public class CheckExcelView extends BaseExcelView  {
   private List<T> vo;

   public CheckExcelView(List<T> vo) {
      this.vo= vo;
   }

   @Override
   protected String getFileName() {
      String time = DateUtils.getLocalFullDateTime14();
      return "导出文件" + time;
   }

   @Override
   protected String getSheetName() {
       return "报表";
   }

   @Override
   protected String[] getTitles() {
      return new String[] { "申请时间"};
   }

   @Override
   protected short[] getColumnWidths() {
      return new short[] { 20};
   }

   @Override
   protected void buildContentCells(Sheet sheet) {
      DecimalFormat df = new DecimalFormat("0.00");
      int rowNum = 1;
      for (T o : vO) {
          Row crow = sheet.createRow(rowNum++);
          crow.createCell(0).setCellValue(o.getApplicationDate()));
      }
   }

}

导出实现 2： XML配置导出  

  1、需要定义XML的配置 export-config.xml

    <?xml version="1.0" encoding="UTF-8"?>

<configuration>
    <table id="demo" name="测试">
        <columns>
            <column id="name" name="名称" width="40"></column>
        </columns>
    </table>
</configuration>

2、XMl解析配置          

@Root
public class Export {

    @ElementList(entry = "table", inline = true)
    private List<Table> table;

    public List<Table> getTable() {
        return table;
    }

    public void setTable(List<Table> table) {
        this.table = table;
    }

    public static class Table {

        @Attribute
        private String id;

        @Attribute
        private String name;


        @ElementList(entry = "column")
        private List<Column> columns;

        public String getId() {
            return id;
        }

        public void setId(String id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public List<Column> getColumns() {
            return columns;
        }

        public void setColumns(List<Column> columns) {
            this.columns = columns;
        }

    }

    public static class Column {

        @Attribute
        private String id;

        @Attribute
        private String name;

        @Attribute
        private short width;

        @Attribute(required = false)
        private String mapping;

        public String getId() {
            return id;
        }

        public void setId(String id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getMapping() {
            return mapping;
        }

        public void setMapping(String mapping) {
            this.mapping = mapping;
        }

        public short getWidth() {
            return width;
        }

        public void setWidth(short width) {
            this.width = width;
        }

    }

}

3、解析XMl方法配置

@Service
public class IExportService {

    private Export tables;

    private Map<String, Export.Table> tableMap;

    @SuppressWarnings("rawtypes")
    @PostConstruct
    public void init() throws Exception {
        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("export-config.xml");
        Serializer serializer = new Persister();
        tables = serializer.read(Export.class, inputStream);
        tableMap = new HashMap<>();
        for (Export.Table table : tables.getTable()) {
            tableMap.put(table.getId(), table);
        }
    }
    public Export.Table getTable(String key) {
        return tableMap.get(key);
    }
}

4、导出基础 ExcelExportView 代码实现

public class ExcelExportView extends BaseExcelView {
    private String[] titles;
    private short[] columnWidths;
    List<Map<String, Object>> results;
    private Export.Table table;
    private IExportService iExportService;
    @Override
    protected String getFileName() {
        return table.getName();
    }
    @Override
    protected String getSheetName() {
        return table.getName();
    }
    @Override
    protected String[] getTitles() {
        return this.titles;
    }
    @Override
    protected short[] getColumnWidths() {
        return this.columnWidths;
    }
    public ExcelExportView() {
        this.iExportService = ApplicationContextProvider.getBean(IExportService.class);
    }
    @Override
    protected void buildContentCells(Sheet sheet) {
        int dataIndex = 1;
        if(CollectionUtils.isEmpty(results)){
            return;
        }
        for (Map<String, Object> data : results) {
            Row row = sheet.createRow(dataIndex++);
            for (int i = 0; i < table.getColumns().size(); i++) {
                Export.Column column = table.getColumns().get(i);
                Cell cell = row.createCell(i);
                Object value = data.get(column.getId());
                if (value == null) {
                    value = "";
                }
                cell.setCellValue(new XSSFRichTextString(value.toString()));
            }
        }
    }
    public void exportExcel(String key, List<Map<String, Object>> results) {
        this.table = iExportService.getTable(key);
        if (null == table) {
            return;
        }
        this.results = results;
        this.titles = new String[table.getColumns().size()];
        this.columnWidths = new short[table.getColumns().size()];
        for (int i = 0; i < table.getColumns().size(); i++) {
            Export.Column column = table.getColumns().get(i);
            titles[i] = column.getName();
            columnWidths[i] = column.getWidth();
        }
    }
}

 最后：导出Controller代码实现  

@RequestMapping(path = "/export", method = RequestMethod.GET, produces = "application/octet-stream;charset=UTF-8")
public @ResponseBody
ModelAndView export(){
    Long loginComId = loginContext.getCompany().getId();
    List<T> list = new ArrayList<>();
    ExcelExportView exportView = new ExcelExportView();
    exportView.exportExcel("XMl中表的ID", BeanUtils.objectToMapList(list));

    return new ModelAndView(exportView);

}