java实现Excel表的导入导出

Posted 2020-10-14

 

注意该方式需要引入 POI jar包

 

先建个 Student 类
public class Student {
 
 private String name;
    private int age;
    private int grade;

}

添加 get set 及其有参、无参构造方法；

 

准备测试数据集创建Excel表格

public class ExcelOperate {

 public static void main(String[] args) {
        // 创建Excel表格
        createExcel(getStudent());

        // 读取Excel表格
        List<Student> list = readExcel();
        System.out.println(list.toString());
    }

    /**
     * 初始化数据
     *
     * @return 数据
     */
    private static List<Student> getStudent() {
        List<Student> list = new ArrayList<Student>();
//        Student student1 = new Student("小明", 8, "二年级");
//        Student student2 = new Student("小光", 9, "三年级");
//        Student student3 = new Student("小花", 10, "四年级");
//        list.add(student1);
//        list.add(student2);
//        list.add(student3);
        return list;
    }

    /**
     * 创建Excel
     *
     * @param list
     *            数据
     */
    private static void createExcel(List<Student> list) {
        // 创建一个Excel文件
        HSSFWorkbook workbook = new HSSFWorkbook();
        // 创建一个工作表
        HSSFSheet sheet = workbook.createSheet("学生表一");
        // 添加表头行
        HSSFRow hssfRow = sheet.createRow(0);
        // 设置单元格格式居中
        HSSFCellStyle cellStyle = workbook.createCellStyle();
        cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);

        // 添加表头内容
        HSSFCell headCell = hssfRow.createCell(0);
        headCell.setCellValue("姓名");
        headCell.setCellStyle(cellStyle);

        headCell = hssfRow.createCell(1);
        headCell.setCellValue("年龄");
        headCell.setCellStyle(cellStyle);

        headCell = hssfRow.createCell(2);
        headCell.setCellValue("年级");
        headCell.setCellStyle(cellStyle);

        // 添加数据内容
        for (int i = 0; i < list.size(); i++) {
            hssfRow = sheet.createRow((int) i + 1);
            Student student = list.get(i);

            // 创建单元格，并设置值
            HSSFCell cell = hssfRow.createCell(0);
            cell.setCellValue(student.getName());
            cell.setCellStyle(cellStyle);

            cell = hssfRow.createCell(1);
            cell.setCellValue(student.getAge());
            cell.setCellStyle(cellStyle);

            cell = hssfRow.createCell(2);
            cell.setCellValue(student.getGrade());
            cell.setCellStyle(cellStyle);
        }

        // 保存Excel文件
        try {
            OutputStream outputStream = new FileOutputStream("D:/students.xls");
            workbook.write(outputStream);
            outputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 读取Excel
     *
     * @return 数据集合
     */
    private static List<Student> readExcel() {
        List<Student> list = new ArrayList<Student>();
        HSSFWorkbook workbook = null;

        try {
            // 读取Excel文件
            InputStream inputStream = new FileInputStream("D:/students.xls");
            workbook = new HSSFWorkbook(inputStream);
            inputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 循环工作表
        for (int numSheet = 0; numSheet < workbook.getNumberOfSheets(); numSheet++) {
            HSSFSheet hssfSheet = workbook.getSheetAt(numSheet);
            if (hssfSheet == null) {
                continue;
            }
            // 循环行
            for (int rowNum = 1; rowNum <= hssfSheet.getLastRowNum(); rowNum++) {
                HSSFRow hssfRow = hssfSheet.getRow(rowNum);
                if (hssfRow == null) {
                    continue;
                }

                // 将单元格中的内容存入集合
                Student student = new Student();

                HSSFCell cell = hssfRow.getCell(0);
                if (cell == null) {
                    continue;
                }
                student.setName(cell.getStringCellValue());

                cell = hssfRow.getCell(1);
                if (cell == null) {
                    continue;
                }
                student.setAge((int) cell.getNumericCellValue());

                cell = hssfRow.getCell(2);
                if (cell == null) {
                    continue;
                }
//                student.setGrade(cell.getStringCellValue());

                list.add(student);
            }
        }
        return list;
    }

}