Java使用poi做加自定义注解实现对象与Excel相互转换
引入依赖
maven
<dependency>
<groupId>org.apache.poigroupId>
<artifactId>poiartifactId>
<version>3.17version>
dependency>
Gradle
implementation group: 'org.apache.poi', name: 'poi', version: '3.17'
代码展示
1、自定义注解类
@Retention(value = RetentionPolicy.RUNTIME)
@Target(value = ElementType.FIELD)
public @interface Excel {
String name();//列的名字
int width() default 6000;//列的宽度
int index() default -1;//决定生成的顺序
boolean isMust() default true; // 是否为必须值,默认是必须的
}
2、Java的Excel对象，只展现了field，get与set方法就忽略了
public class GoodsExcelModel {
@Excel(name = "ID_禁止改动", index = 0, width = 0)
private Long picId;//picId
@Excel(name = "产品ID_禁止改动", index = 1, width = 0)
private Long productId;
@Excel(name = "型号", index = 3)
private String productName;//产品型号
@Excel(name = "系列", index = 2)
private String seriesName;//系列名字
@Excel(name = "库存", index = 5)
private Long quantity;
@Excel(name = "属性值", index = 4)
private String propValue;
@Excel(name = "价格", index = 6)
private Double price;
@Excel(name = "商品编码", index = 7, isMust = false)
private String outerId;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long dbId; // 数据库自增长id
private Date createTime; // 记录创建时间
}
3、Excel表格与对象转换的工具类，使用时指定泛型参数和泛型的class即可
public class ExcelUtil {
private static final String GET = "get";
private static final String SET = "set";
private static Logger logger = LoggerFactory.getLogger(ExcelUtil.class);
/**
* 将对象转换成Excel
*
* @param objList 需要转换的对象
* @return 返回是poi中的对象
*/
public static HSSFWorkbook toExcel(List objList) {
if (CollectionUtils.isEmpty(objList)) throw new NullPointerException("无效的数据");
Class aClass = objList.get(0).getClass();
Field[] fields = aClass.getDeclaredFields();
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet();
for (int i = 0; i < objList.size(); i++) {
HSSFRow row = sheet.createRow(i + 1);//要从第二行开始写
HSSFRow topRow = null;
if (i == 0) topRow = sheet.createRow(0);
for (Field field : fields) {
Excel excel = field.getAnnotation(Excel.class);//得到字段是否使用了Excel注解
if (excel == null) continue;
HSSFCell cell = row.createCell(excel.index());//设置当前值放到第几列
String startName = field.getName().substring(0, 1);
String endName = field.getName().substring(1, field.getName().length());
String methodName = new StringBuffer(GET).append(startName.toUpperCase()).append(endName).toString();
try {
Method method = aClass.getMethod(methodName);//根据方法名获取方法,用于调用
Object invoke = method.invoke(objList.get(i));
if (invoke == null) continue;
cell.setCellValue(invoke.toString());
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
if (topRow == null) continue;
HSSFCell topRowCell = topRow.createCell(excel.index());
topRowCell.setCellValue(excel.name());
sheet.setColumnWidth(excel.index(), excel.width());
}
}
return workbook;
}
/**
* 将Excel文件转换为指定对象
*
* @param file 传入的Excel
* @param c 需要被指定的class
* @return
* @throws IOException
* @throws IllegalAccessException
* @throws InstantiationException
*/
public static <T> List<T> excelFileToObject(MultipartFile file, Class<T> c) throws IOException, IllegalAccessException, InstantiationException {
//key为反射得到的下标,value为对于的set方法
Map<Integer, String> methodMap = new HashMap<>();
//保存第一列的值与对应的下标,用于验证用户是否删除了该列,key为下标,value为名字
Map<Integer, String> startRowNameMap = new HashMap<>();
//用来记录当前参数是否为必须的
Map<Integer, Boolean> fieldIsMustMap = new HashMap<>();
//得到所有的字段
Field[] fields = c.getDeclaredFields();
for (Field field : fields) {
Excel excel = field.getAnnotation(Excel.class);
if (excel == null) continue;
String startName = field.getName().substring(0, 1);
String endName = field.getName().substring(1, field.getName().length());
String methodName = new StringBuffer(SET).append(startName.toUpperCase()).append(endName).toString();
methodMap.put(excel.index(), methodName);
startRowNameMap.put(excel.index(), excel.name());
fieldIsMustMap.put(excel.index(), excel.isMust());
}
String fileName = file.getOriginalFilename();
Workbook wb = fileName.endsWith(".xlsx") ? new XSSFWorkbook(file.getInputStream()) : new HSSFWorkbook(file.getInputStream());
Sheet sheet = wb.getSheetAt(0);
Row sheetRow = sheet.getRow(0);
for (Cell cell : sheetRow) {
Integer columnIndex = cell.getColumnIndex();
if (cell.getCellTypeEnum() != CellType.STRING) throw new ExcelException("excel校验失败, 请勿删除文件中第一行数据 !!!");
String value = cell.getStringCellValue();
String name = startRowNameMap.get(columnIndex);
if (name == null) throw new ExcelException("excel校验失败,请勿移动文件中任何列的顺序!!!");
if (!name.equals(value)) throw new ExcelException("excel校验失败,【" + name + "】列被删除,请勿删除文件中任何列 !!!");
}
sheet.removeRow(sheetRow);//第一行是不需要被反射赋值的
List<T> models = new ArrayList<>();
for (Row row : sheet) {
if (row == null || !checkRow(row)) continue;
T obj = c.newInstance();//创建新的实例化对象
Class excelModelClass = obj.getClass();
startRowNameMap.entrySet().forEach(x -> {
Integer index = x.getKey();
Cell cell = row.getCell(index);
String methodName = methodMap.get(index);
if (StringUtils.isEmpty(methodName)) return;
List<Method> methods = Lists.newArrayList(excelModelClass.getMethods()).stream()
.filter(m -> m.getName().startsWith(SET)).collect(Collectors.toList());
String rowName = startRowNameMap.get(index);//列的名字
for (Method method : methods) {
if (!method.getName().startsWith(methodName)) continue;
//检测value属性
String value = valueCheck(cell, rowName, fieldIsMustMap.get(index));
//开始进行调用方法反射赋值
methodInvokeHandler(obj, method, value);
}
});
models.add(obj);
}
return models;
}
/**
* 检测当前需要赋值的value
*
* @param cell 当前循环行中的列对象
* @param rowName 列的名字{@link Excel}中的name
* @param isMust 是否为必须的
* @return 值
*/
private static String valueCheck(Cell cell, String rowName, Boolean isMust) {
//有时候删除单个数据会造成cell为空,也可能是value为空
if (cell == null && isMust) {
throw new ExcelException("excel校验失败,【" + rowName + "】中的数据禁止单个删除");
}
if (cell == null) return null;
cell.setCellType(CellType.STRING);
String value = cell.getStringCellValue();
if ((value == null || value.trim().isEmpty()) && isMust) {
throw new ExcelException("excel校验失败,【" + rowName + "】中的数据禁止单个删除");
}
return value;
}
/**
* 反射赋值的处理的方法
*
* @param obj 循环创建的需要赋值的对象
* @param method 当前对象期中一个set方法
* @param value 要被赋值的内容
*/
private static void methodInvokeHandler(Object obj, Method method, String value) {
Class<?> parameterType = method.getParameterTypes()[0];
try {
if (parameterType == null) {
method.invoke(obj);
return;
}
String name = parameterType.getName();
if (name.equals(String.class.getName())) {
method.invoke(obj, value);
return;
}
if (name.equals(Long.class.getName())) {
method.invoke(obj, Long.valueOf(value));
return;
}
if (name.equals(Double.class.getName())) {
method.invoke(obj, Double.valueOf(value));
}
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
private static boolean checkRow(Row row) {
try {
if (row == null) return false;
short firstCellNum = row.getFirstCellNum();
short lastCellNum = row.getLastCellNum();
if (firstCellNum < 0 && lastCellNum < 0) return false;
if (firstCellNum != 0) {
for (short i = firstCellNum; i < lastCellNum; i++) {
Cell cell = row.getCell(i);
String cellValue = cell.getStringCellValue();
if (!StringUtils.isBlank(cellValue)) return true;
}
return false;
}
return true;
} catch (Exception e) {
return true;
}
}
4、导出Excel与导入Excel的示例代码
使用展示
1、选择数据
2、设置基本数据，然后导出表格
3、导出表格效果，在图片中看到A和B列没有显示出来，这是因为我将其宽度配置为了0
4、将必须参数删除后上传测试，如下图中，商品编码我设置isMust为false所以删除数据就不会出现此问题。会提示验证失败，具体错误查看图片
5、将列中值的顺序调整测试，也会提示验证失败,具体效果如下图
6、正常上传测试，具体效果下如图
