java - 在 Spring 为 excel 生成运行一个短暂的后台任务

Question

在我的项目中，要求是在后台进程中生成 EXCEL 文件(我用 POI 完成了)。当用户单击 excel generate 时，后台进程将运行并生成 excel 并通知用户 excel 已准备好下载(使用 Velocity 完成)。我有 20 多个任务需要生成一个 excel 文件。所有任务都应在后台运行，以便用户可以顺利访问整个应用程序。我们用来获取 excel 文件数据的数据库是 MYSQL

提前致谢。

Answer 1

新建一个excel文件

import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
//..
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet("Sample sheet");
//Create a new row in current sheet
Row row = sheet.createRow(0);
//Create a new cell in current row
Cell cell = row.createCell(0);
//Set value to new value
cell.setCellValue("Blahblah");

下面是用虚拟数据编写一个新的 excel 的完整代码:

HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet("Sample sheet");

        Map<string, object[]=""> data = new HashMap<string, object[]="">();
        data.put("1", new Object[] {"Emp No.", "Name", "Salary"});
        data.put("2", new Object[] {1d, "John", 1500000d});
        data.put("3", new Object[] {2d, "Sam", 800000d});
        data.put("4", new Object[] {3d, "Dean", 700000d});

        Set<string> keyset = data.keySet();
        int rownum = 0;
        for (String key : keyset) {
            Row row = sheet.createRow(rownum++);
            Object [] objArr = data.get(key);
            int cellnum = 0;
            for (Object obj : objArr) {
                Cell cell = row.createCell(cellnum++);
                if(obj instanceof Date) 
                    cell.setCellValue((Date)obj);
                else if(obj instanceof Boolean)
                    cell.setCellValue((Boolean)obj);
                else if(obj instanceof String)
                    cell.setCellValue((String)obj);
                else if(obj instanceof Double)
                    cell.setCellValue((Double)obj);
            }
        }

        try {
            FileOutputStream out = 
                    new FileOutputStream(new File("C:\\new.xls"));
            workbook.write(out);
            out.close();
            System.out.println("Excel written successfully..");

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }