導入依賴:

<!-- excel工具 -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>${poi.version}</version>
        </dependency>

在实体变量上添加@Excel注解

@Excel(name = "用户序号", prompt = "用户编号")
private Long userId;

@Excel(name = "用户名称")
private String userName;

@Excel(name = "用户性别", readConverterExp = "0=男,1=女,2=未知")
private String sex;

@Excel(name = "最后登陆时间", width = 30, dateFormat = "yyyy-MM-dd HH:mm:ss")
private Date loginDate;

撰寫工具類:

public class ExcelUtil<T>
{
 。。。。。省略N行代碼
/**
     * 对excel表单指定表格索引名转换成list
     * 
     * @param sheetName 表格索引名
     * @param is 输入流
     * @return 转换后集合
     */
    public List<T> importExcel(String sheetName, InputStream is) throws Exception
    {
        this.type = Type.IMPORT;
        this.wb = WorkbookFactory.create(is);
        List<T> list = new ArrayList<T>();
        Sheet sheet = null;
        if (StringUtils.isNotEmpty(sheetName))
        {
            // 如果指定sheet名,则取指定sheet中的内容.
            sheet = wb.getSheet(sheetName);
        }
        else
        {
            // 如果传入的sheet名不存在则默认指向第1个sheet.
            sheet = wb.getSheetAt(0);
        }

        if (sheet == null)
        {
            throw new IOException("文件sheet不存在");
        }

        int rows = sheet.getPhysicalNumberOfRows();

        if (rows > 0)
        {
            // 定义一个map用于存放excel列的序号和field.
            Map<String, Integer> cellMap = new HashMap<String, Integer>();
            // 获取表头
            Row heard = sheet.getRow(0);
            for (int i = 0; i < heard.getPhysicalNumberOfCells(); i++)
            {
                Cell cell = heard.getCell(i);
                if (StringUtils.isNotNull(cell != null))
                {
                    String value = this.getCellValue(heard, i).toString();
                    cellMap.put(value, i);
                }
                else
                {
                    cellMap.put(null, i);
                }
            }
            // 有数据时才处理 得到类的所有field.
            Field[] allFields = clazz.getDeclaredFields();
            // 定义一个map用于存放列的序号和field.
            Map<Integer, Field> fieldsMap = new HashMap<Integer, Field>();
            for (int col = 0; col < allFields.length; col++)
            {
                Field field = allFields[col];
                Excel attr = field.getAnnotation(Excel.class);
                if (attr != null && (attr.type() == Type.ALL || attr.type() == type))
                {
                    // 设置类的私有字段属性可访问.
                    field.setAccessible(true);
                    Integer column = cellMap.get(attr.name());
                    fieldsMap.put(column, field);
                }
            }
            for (int i = 1; i < rows; i++)
            {
                // 从第2行开始取数据,默认第一行是表头.
                Row row = sheet.getRow(i);
                T entity = null;
                for (Map.Entry<Integer, Field> entry : fieldsMap.entrySet())
                {
                    Object val = this.getCellValue(row, entry.getKey());

                    // 如果不存在实例则新建.
                    entity = (entity == null ? clazz.newInstance() : entity);
                    // 从map中得到对应列的field.
                    Field field = fieldsMap.get(entry.getKey());
                    // 取得类型,并根据对象类型设置值.
                    Class<?> fieldType = field.getType();
                    if (String.class == fieldType)
                    {
                        String s = Convert.toStr(val);
                        if (StringUtils.endsWith(s, ".0"))
                        {
                            val = StringUtils.substringBefore(s, ".0");
                        }
                        else
                        {
                            String dateFormat = field.getAnnotation(Excel.class).dateFormat();
                            if (StringUtils.isNotEmpty(dateFormat))
                            {
                                val = DateUtils.parseDateToStr(dateFormat, (Date) val);
                            }
                            else
                            {
                                val = Convert.toStr(val);
                            }
                        }
                    }
                    else if ((Integer.TYPE == fieldType) || (Integer.class == fieldType))
                    {
                        val = Convert.toInt(val);
                    }
                    else if ((Long.TYPE == fieldType) || (Long.class == fieldType))
                    {
                        val = Convert.toLong(val);
                    }
                    else if ((Double.TYPE == fieldType) || (Double.class == fieldType))
                    {
                        val = Convert.toDouble(val);
                    }
                    else if ((Float.TYPE == fieldType) || (Float.class == fieldType))
                    {
                        val = Convert.toFloat(val);
                    }
                    else if (BigDecimal.class == fieldType)
                    {
                        val = Convert.toBigDecimal(val);
                    }
                    else if (Date.class == fieldType)
                    {
                        if (val instanceof String)
                        {
                            val = DateUtils.parseDate(val);
                        }
                        else if (val instanceof Double)
                        {
                            val = DateUtil.getJavaDate((Double) val);
                        }
                    }
                    if (StringUtils.isNotNull(fieldType))
                    {
                        Excel attr = field.getAnnotation(Excel.class);
                        String propertyName = field.getName();
                        if (StringUtils.isNotEmpty(attr.targetAttr()))
                        {
                            propertyName = field.getName() + "." + attr.targetAttr();
                        }
                        else if (StringUtils.isNotEmpty(attr.readConverterExp()))
                        {
                            val = reverseByExp(String.valueOf(val), attr.readConverterExp());
                        }
                        ReflectUtils.invokeSetter(entity, propertyName, val);
                    }
                }
                list.add(entity);
            }
        }
        return list;
    }
    。。。。。。。。。

食用:

 ExcelUtil<User> util = new ExcelUtil<User>(User.class);
        List<User> userList = util.importExcel(file.getInputStream());
        String message = userService.importUser(userList, updateSupport);
List<User> list = userService.selectUserList(user);
        ExcelUtil<User> util = new ExcelUtil<User>(User.class);
        return util.exportExcel(list, "用户数据");

一个好奇的人