利用註解實現簡單的excel數據讀取,利用註解對類的屬性和excel中的表頭映射,使用Apache的poi就不用在業務代碼中涉及row,rows這些屬性了。java
定義註解:app
@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.FIELD) public @interface Excel { String name(); }
因爲本例中只涉及根據Excel表頭部分對Excel進行解析,只定義了一個name做爲和Excel表頭的隱射。工具
工具類完整代碼以下:this
public class ExcelUtil<T> { Class<T> clazz; public ExcelUtil(Class<T> clazz) { this.clazz = clazz; } public List<T> importExcel(String sheetName, InputStream input) { int maxCol = 0; List<T> list = new ArrayList<T>(); try { Workbook workbook = WorkbookFactory.create(input); Sheet sheet = workbook.getSheet(sheetName); // 若是指定sheet名,則取指定sheet中的內容. if (!sheetName.trim().equals("")) { sheet = workbook.getSheet(sheetName); } // 若是傳入的sheet名不存在則默認指向第1個sheet. if (sheet == null) { sheet = workbook.getSheetAt(0); } int rows = sheet.getPhysicalNumberOfRows(); // 有數據時才處理 if (rows > 0) { List<Field> allFields = getMappedFiled(clazz, null); // 定義一個map用於存放列的序號和field. Map<Integer, Field> fieldsMap = new HashMap<Integer, Field>(); // 第一行爲表頭 Row rowHead = sheet.getRow(0); Map<String, Integer> cellMap = new HashMap<>(); int cellNum = rowHead.getPhysicalNumberOfCells(); for (int i = 0; i < cellNum; i++){ cellMap.put(rowHead.getCell(i).getStringCellValue().toLowerCase(), i); } for (Field field : allFields) { // 將有註解的field存放到map中. if (field.isAnnotationPresent(Excel.class)) { Excel attr = field.getAnnotation(Excel.class); // 根據Name來獲取相應的failed int col = cellMap.get(attr.name().toLowerCase()); field.setAccessible(true); fieldsMap.put(col, field); } } // 從第2行開始取數據 for (int i = 1; i < rows; i++) { Row row = sheet.getRow(i); T entity = null; for (int j = 0; j < cellNum; j++) { Cell cell = row.getCell(j); if (cell == null) { continue; } int cellType = cell.getCellType(); String c = ""; if (cellType == HSSFCell.CELL_TYPE_NUMERIC) { DecimalFormat df = new DecimalFormat("0"); c = df.format(cell.getNumericCellValue()); } else if (cellType == HSSFCell.CELL_TYPE_BOOLEAN) { c = String.valueOf(cell.getBooleanCellValue()); } else { c = cell.getStringCellValue(); } if (c == null || c.equals("")) { continue; } entity = (entity == null ? clazz.newInstance() : entity); // 從map中獲得對應列的field. Field field = fieldsMap.get(j); if (field == null) { continue; } // 取得類型,並根據對象類型設置值. Class<?> fieldType = field.getType(); if (String.class == fieldType) { field.set(entity, String.valueOf(c)); } else if ((Integer.TYPE == fieldType) || (Integer.class == fieldType)) { field.set(entity, Integer.valueOf(c)); } else if ((Long.TYPE == fieldType) || (Long.class == fieldType)) { field.set(entity, Long.valueOf(c)); } else if ((Float.TYPE == fieldType) || (Float.class == fieldType)) { field.set(entity, Float.valueOf(c)); } else if ((Short.TYPE == fieldType) || (Short.class == fieldType)) { field.set(entity, Short.valueOf(c)); } else if ((Double.TYPE == fieldType) || (Double.class == fieldType)) { field.set(entity, Double.valueOf(c)); } else if (Character.TYPE == fieldType) { if (c.length() > 0) { field.set(entity, c.charAt(0)); } } } if (entity != null) { list.add(entity); } } } } catch (Exception e) { e.printStackTrace(); } return list; } /** * 獲得實體類全部經過註解映射了數據表的字段 * * @param clazz * @param fields * @return */ private List<Field> getMappedFiled(Class clazz, List<Field> fields) { if (fields == null) { fields = new ArrayList<Field>(); } // 獲得全部定義字段 Field[] allFields = clazz.getDeclaredFields(); // 獲得全部field並存放到一個list中. for (Field field : allFields) { if (field.isAnnotationPresent(Excel.class)) { fields.add(field); } } if (clazz.getSuperclass() != null && !clazz.getSuperclass().equals(Object.class)) { getMappedFiled(clazz.getSuperclass(), fields); } return fields; } }
代碼很簡單,獲取sheet,解析第一行,並和實體類標有註解的字段一一對應,用hashMap記錄下來,而後循環取得Excel中剩下全部的數據,根據map的對應關係將值set到對應字段。3d
待解析表格以下:excel
定義實體類:code
public class User { @Excel(name = "filed1") private String name; @Excel(name = "filed2") private String nameEn; @Excel(name = "filed3") private Integer age; @Excel(name = "filed4") private String six; @Excel(name = "filed5") private String weight; // ...getter setter }
使用工具類:orm
public static void main (String[] args) { FileInputStream fileInputStream = null; try { fileInputStream = new FileInputStream("D://data.xlsx"); } catch (FileNotFoundException e) { e.printStackTrace(); } ExcelUtil<User> util = new ExcelUtil<>(User.class); List<User> jalanHotelList = util.importExcel("user", fileInputStream); // do something }
利用這個思路能夠擴展出導出excel功能,利用註解指定導出的excel表頭,甚至能夠輕鬆控制excel表頭的顏色,合併屬性等等,在xdemo中有詳細複雜的示例,能夠研究下。因爲個人需求很簡單,就不整那麼複雜啦。對象