JavaPOI报表反射+自定义注解优化
一.应用背景
Java目前用来处理报表功能一般选用的都是POI,项目中需要报表的
地方越来越多之后,往往会遇到这样一个问题,每次涉及到报表时,写的代码都是一模一样的,无非是封装的数据类型发生了变化,虽然大家都知道ctrl+c,ctrl+v,但这种扩展性极差的代码毫无疑问是我们必须要去解决的问题,于是慢慢的,大家想到了反射,通过反射去获取你要填入表格的值,可以说是很大程度上解决了代码的冗余问题,也极高地增强了代码的可扩展性.
但是,这样还是会面对一些问题,对于表格的标题行还是需要人为的去手动设置,报表每变动一次,就需要去改一下代码,这当然不是我们愿意看到的,久而久之,有些聪明但是懒惰的程序员又想出了一个解决之道,通过注解,我标注属性对应的是哪个标题,在反射的时候读取注解中的标题,在构建第一行时,读取属性的标题,填充进去,不管你怎么改怎么动,我只需要对我的entity类的属性以及注解内容做修改就行了,完美的解决了扩展性的问题.
下面.我就从代码量,原理上做一些解答[PS:下面的代码除了工具类之外,都是不完整的,想完全复制了去测试的大佬们还是算了吧]
二.代码量对比
1.没有优化的controller核心代码
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
String filename = "入库报表";
List<TbWmsreportPurchase> list = null;
list = (List<TbWmsreportPurchase>) JSONArray.parseArray(data,
TbWmsreportPurchase.class);
// 声明一个工作薄
HSSFWorkbook workbook = new HSSFWorkbook();
// 生成一个sheet,对应Excel文件中的sheet
HSSFSheet sheet = workbook.createSheet("入库报表");
// 设置表格默认列宽度为15个字节
sheet.setDefaultColumnWidth(20);
// 生成一个样式
HSSFCellStyle style = workbook.createCellStyle();
// 设置这些样式
style.setAlignment(HorizontalAlignment.CENTER);
style.setVerticalAlignment(VerticalAlignment.CENTER);
// // 生成一个字体
HSSFFont font = workbook.createFont();
font.setFontName("仿宋_GB2312");
font.setBold(true);
font.setFontHeightInPoints((short) 16);
style.setFont(font);
HSSFRow row0 = sheet.createRow(0);
sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, 4));
HSSFCell cell_0_0 = row0.createCell(0);
cell_0_0.setCellValue("入库报表");
cell_0_0.setCellStyle(style);
HSSFRow row1 = sheet.createRow(1);
HSSFCell cell_1_0 = row1.createCell(0);
cell_1_0.setCellValue("时间");
cell_1_0.setCellStyle(style);
HSSFCell cell_1_1 = row1.createCell(1);
cell_1_1.setCellValue("员工姓名");
cell_1_1.setCellStyle(style);
HSSFCell cell_1_2 = row1.createCell(2);
cell_1_2.setCellValue("签收包裹量");
cell_1_2.setCellStyle(style);
HSSFCell cell_1_3 = row1.createCell(3);
cell_1_3.setCellValue("贴标商品数量");
cell_1_3.setCellStyle(style);
HSSFCell cell_1_4 = row1.createCell(4);
cell_1_4.setCellValue("贴标商品种类");
cell_1_4.setCellStyle(style);
HSSFCell cell_1_5 = row1.createCell(5);
cell_1_5.setCellValue("上架商品数量");
cell_1_5.setCellStyle(style);
HSSFCell cell_1_6 = row1.createCell(6);
cell_1_6.setCellValue("上架商品种类");
cell_1_6.setCellStyle(style);
if(list != null && list.size() > 0) {
int k = 2;
for(TbWmsreportPurchase pp:list) {
HSSFRow row = sheet.createRow(k);
HSSFCell cell0 = row.createCell(0);
cell0.setCellValue(pp.getCountTimeStr());
cell0.setCellStyle(style);
HSSFCell cell1 = row.createCell(1);
cell1.setCellValue(pp.getEmployeeName());
cell1.setCellStyle(style);
HSSFCell cell2 = row.createCell(2);
cell2.setCellValue(pp.getSingleCount());
cell2.setCellStyle(style);
HSSFCell cell3 = row.createCell(3);
cell3.setCellValue(pp.getLableQuantity());
cell3.setCellStyle(style);
HSSFCell cell4 = row.createCell(4);
cell4.setCellValue(pp.getLableCount());
cell4.setCellStyle(style);
HSSFCell cell5 = row.createCell(5);
cell5.setCellValue(pp.getPutawayQuantity());
cell5.setCellStyle(style);
HSSFCell cell6 = row.createCell(6);
cell6.setCellValue(pp.getPutawayCount());
cell6.setCellStyle(style);
k++;
}
}
workbook.write(outStream);
filename = "入库报表" + sdf.format(new Date()) + ".xls";
byte[] bytes = outStream.toByteArray();
response.setContentType("application/vnd.ms-excel");
response.setContentLength(bytes.length);
response.setHeader("Content-Disposition",
"attachment;filename=" + new String(filename.getBytes("GB2312"), "8859_1"));
response.getOutputStream().write(bytes);
2.反射优化后的controller和工具类
controller核心代码
HSSFWorkbook workbook = null;
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
String title = "出库日志报表";
int code = 0;
RetCode rt = getTaskHistoryList(request, session);
if(rt.getAck() == 0) {
@SuppressWarnings("unchecked")
List<TaskOrderAndItemHistory> list = (List<TaskOrderAndItemHistory>) rt.getData();
if(list != null && list.size() > 0) {
LinkedHashMap<String, String> headers = new LinkedHashMap<String, String>();
headers.put("platformOrderId", "订单编号");
headers.put("groupid", "批次");
headers.put("pickBasket", "配货篮子编号");
headers.put("basketNum", "分解篮子编号");
headers.put("orderWeight", "称重重量");
headers.put("stockWarehouse", "仓库");
headers.put("itemCount", "订单下商品种类");
headers.put("itemQuantity", "订单下商品的累计总个数");
headers.put("orderTime", "订单时间");
headers.put("pickOper", "配货人");
headers.put("pickTime", "配货时间");
headers.put("resolveOper", "分解员");
headers.put("resolveTime", "分解时间");
headers.put("shipOper", "发货员");
headers.put("shipTime", "发货时间");
headers.put("trackNumber", "物流单号");
headers.put("myLogisticsChannel", "物流渠道");
headers.put("myLogistics","物流公司");
RetCode rts = excelUtil.exportExcel(title, headers, list, outStream);
if(rts.getAck()==0){
title = "taskHistoryList.xls";
byte[] bytes = outStream.toByteArray();
response.setContentType("application/vnd.ms-excel");
response.setContentLength(bytes.length);
response.setHeader("Content-Disposition", "attachment;filename=" + title);
response.getOutputStream().write(bytes);
code = 1;
}else{
workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet(title);
HSSFRow titleRow = sheet.createRow(0);
titleRow.createCell(0).setCellValue("无需要导出的记录！");
}
headers.clear();headers = null;
}else {
workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet(title);
HSSFRow titleRow = sheet.createRow(0);
titleRow.createCell(0).setCellValue("没有订单数据!");
}
}else {
workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet(title);
HSSFRow titleRow = sheet.createRow(0);
titleRow.createCell(0).setCellValue(rt.getMsg());
}
工具类
public <T> RetCode exportExcel(String title,
LinkedHashMap<String, String> headers, Collection<T> dataset,
ByteArrayOutputStream outStream) {
RetCode rt = new RetCode();
if (headers == null || dataset == null) {
rt.setAck(1000);
rt.setMsg("导出的数据不能为空！");
return rt;
}
// 声明一个工作薄
HSSFWorkbook workbook = new HSSFWorkbook();
// 生成一个sheet,对应Excel文件中的sheet
HSSFSheet sheet = workbook.createSheet(title);
// 设置表格默认列宽度为15个字节
sheet.setDefaultColumnWidth(20);
// 生成一个样式
HSSFCellStyle style = workbook.createCellStyle();
// 设置这些样式
style.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// // 生成一个字体
HSSFFont font = workbook.createFont();
// font.setColor(HSSFColor.VIOLET.index);
font.setFontHeightInPoints((short) 12);
font.setBold(true);;//HSSFFont.BOLDWEIGHT_BOLD
// // 把字体应用到当前的样式
style.setFont(font);
// 产生表格标题行
HSSFRow row = sheet.createRow(0);
int ii = 0;
for (Map.Entry<String, String> entry : headers.entrySet()) {
HSSFCell cell = row.createCell(ii);
cell.setCellStyle(style);
HSSFRichTextString text = new HSSFRichTextString(entry.getValue());
cell.setCellValue(text);
ii++;
}
// 生成一个样式
style = workbook.createCellStyle();
// 设置这些样式
style.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// // 生成一个字体
font = workbook.createFont();
font.setFontHeightInPoints((short) 12);
font.setBold(true);
/** 数字小于0的样式 */
HSSFCellStyle style2 = workbook.createCellStyle();
// 设置这些样式
style2.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// // 生成一个字体
HSSFFont font2 = workbook.createFont();
font2.setFontHeightInPoints((short) 14);
font2.setBold(true);
font2.setColor(HSSFColor.RED.index);
style2.setFont(font2);
/** 数字大于0的样式 */
HSSFCellStyle style3 = workbook.createCellStyle();
// 设置这些样式
style3.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// // 生成一个字体
HSSFFont font3 = workbook.createFont();
font3.setFontHeightInPoints((short) 14);
font3.setBold(true);
font3.setColor(HSSFColor.GREEN.index);
style3.setFont(font3);
// 遍历集合数据，产生数据行
Iterator<T> it = dataset.iterator();
SimpleDateFormat sim = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
int index = 0;
while (it.hasNext()) {
index++;
row = sheet.createRow(index);
T t = (T) it.next();
// 利用反射，根据javabean属性的先后顺序，动态调用getXxx()方法得到属性值
Field[] fields = t.getClass().getDeclaredFields();
int j = 0;
for (Map.Entry<String, String> entry : headers.entrySet()) {
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
String fieldName = field.getName();
if (!Sys.isCheckNull(fieldName).equals(entry.getKey())) {
continue;
}
HSSFCell cell = row.createCell(j);
cell.setCellStyle(style);
String getMethodName = "get"
+ fieldName.substring(0, 1).toUpperCase()
+ fieldName.substring(1);
try {
@SuppressWarnings("rawtypes")
Class tCls = t.getClass();
@SuppressWarnings("unchecked")
Method getMethod = tCls.getMethod(getMethodName,
new Class[] {
});
Object value = getMethod.invoke(t, new Object[] {
});
Object valueType = getMethod.getReturnType();
// 判断值的类型后进行强制类型转换
String textValueType = valueType == null ? ""
: valueType.toString();
String textValue = value == null ? "" : value
.toString();
if (textValueType.indexOf(".Integer") > 0
|| textValueType.indexOf(".int") > 0
|| textValueType.indexOf("Integer") >= 0
|| textValueType.indexOf("int") >= 0) {
if (Sys.isCheckInt(textValue) < 0) {
cell.setCellStyle(style2);
} else {
cell.setCellStyle(style3);
}
cell.setCellValue(Sys.isCheckInt(textValue));
} else if (textValueType.indexOf(".Long") > 0
|| textValueType.indexOf(".long") > 0
|| textValueType.indexOf("Long") >= 0
|| textValueType.indexOf("long") >= 0) {
if (Sys.isCheckLong(textValue) < 0) {
cell.setCellStyle(style2);
} else {
cell.setCellStyle(style3);
}
cell.setCellValue(Sys.isCheckLong(textValue));
} else if (textValueType.indexOf(".Double") > 0
|| textValueType.indexOf(".double") > 0
|| textValueType.indexOf("Double") >= 0
|| textValueType.indexOf("double") >= 0) {
if (Sys.isCheckDouble(textValue) < 0) {
cell.setCellStyle(style2);
} else {
cell.setCellStyle(style3);
}
cell.setCellValue(Sys.isCheckDouble(textValue));
} else if (textValueType.indexOf(".Date") > 0) {
Date dateval = (Date) getMethod.invoke(t, new Object[] {
});
if(dateval != null) {
cell.setCellValue(sim.format(dateval));
}else {
cell.setCellValue("");
}
} else {
cell.setCellValue(textValue);
}
textValueType = null;
textValue = null;
} catch (NoSuchMethodException e) {
e.printStackTrace();
rt.setAck(1000);
rt.setMsg(e.getMessage());
} catch (IllegalAccessException e) {
e.printStackTrace();
rt.setAck(1000);
rt.setMsg(e.getMessage());
} catch (InvocationTargetException e) {
e.printStackTrace();
rt.setAck(1000);
rt.setMsg(e.getMessage());
}
}
j++;
}
}
try {
workbook.write(outStream);
rt.setAck(0);
rt.setMsg("导出成功!");
} catch (IOException e) {
System.out.println("IOException错误:" + e.getMessage());
rt.setAck(1000);
rt.setMsg(e.getMessage());
} catch (Exception e) {
System.out.println("Exception错误:" + e.getMessage());
rt.setAck(1000);
rt.setMsg(e.getMessage());
}
return rt;
}
public String getCellValue(Cell cell) {
String cellValue = "";
if (cell == null) {
return cellValue;
}
// 把数字当成String来读，避免出现1读成1.0的情况
if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
cell.setCellType(Cell.CELL_TYPE_STRING);
}
// 判断数据的类型
switch (cell.getCellType()) {
case Cell.CELL_TYPE_NUMERIC: // 数字
cellValue = String.valueOf(cell.getNumericCellValue());
break;
case Cell.CELL_TYPE_STRING: // 字符串
cellValue = String.valueOf(cell.getStringCellValue());
break;
case Cell.CELL_TYPE_BOOLEAN: // Boolean
cellValue = String.valueOf(cell.getBooleanCellValue());
break;
case Cell.CELL_TYPE_FORMULA: // 公式
cellValue = String.valueOf(cell.getCellFormula());
break;
case Cell.CELL_TYPE_BLANK: // 空值
cellValue = "";
break;
case Cell.CELL_TYPE_ERROR: // 故障
cellValue = "非法字符";
break;
default:
cellValue = "未知类型";
break;
}
return cellValue;
}
3.反射+自定义注解优化后的controller和工具类
controller核心代码
HSSFWorkbook workbook = null;
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
String title = "出库订单商品报表";
RetCode rc = getTaskHistoryList(request, session);
String fileName = "taskAndItemHistoryList.xls";
if(rc.getAck()==0 && !StringUtils.isEmpty(rc.getData())) {
@SuppressWarnings("unchecked")
List<TaskOrderAndItemHistory> list = (List<TaskOrderAndItemHistory>)rc.getData();
//导出的订单数据集合
List<TaskOrderAndItemHistoryExcel> orderList = new ArrayList<>();
for(TaskOrderAndItemHistory tat : list) {
TaskOrderAndItemHistoryExcel tate = new TaskOrderAndItemHistoryExcel();
//商品详情
List<TbTaskItemHistoryExcel> itemList = new ArrayList<>();
if(tat.getItemList()!=null && tat.getItemList().size()>0) {
for(TbTaskItemHistory ttih : tat.getItemList()) {
TbTaskItemHistoryExcel t = new TbTaskItemHistoryExcel();
BeanCopier copier =BeanCopier.create(ttih.getClass(), t.getClass(), false);
copier.copy(ttih, t, null);
itemList.add(t);
}
}
if(!itemList.isEmpty()) {
tate.setItems(itemList);
}
BeanCopier copier =BeanCopier.create(tat.getClass(), tate.getClass(), false);
copier.copy(tat, tate, null);
orderList.add(tate);
}
createExcel.exportExcel(orderList, TaskOrderAndItemHistoryExcel.class,null, outputStream, title,0);
outputStream.flush();
byte[] bytes = outputStream.toByteArray();
response.setContentType("application/vnd.ms-excel");
response.setContentLength(bytes.length);
response.setHeader("Content-Disposition", "attachment;filename=" + fileName);
response.getOutputStream().write(bytes);
return ;
工具类
@Component
public class CreateExcel2 {
/**
* 反射递归报表(嵌套List)
* @param dataset 反射的数据集
* @param clazz 反射的数据类型
* @param workbook 工作簿
* @param outStream 字节数组输出流
* @param sheetName 表名
* @param currentRow 当前行
* @throws IOException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
@SuppressWarnings({
"deprecation" })
public <T> void exportExcel(List<T> dataset,Class<T> clazz,HSSFWorkbook workbook,
ByteArrayOutputStream outStream,String sheetName,int currentRow) throws IOException, IllegalArgumentException, IllegalAccessException {
//每次执行时重置流,否则递归写入的文件内容会被覆盖掉
outStream.reset();
if(workbook==null) {
workbook = new HSSFWorkbook();
}
if(dataset == null || dataset.size() <= 0) {
HSSFSheet sheet = workbook.createSheet(sheetName);
HSSFRow titleRow = sheet.createRow(currentRow);
titleRow.createCell(0).setCellValue("没有要导出的记录！");
workbook.write(outStream);
return ;
}
HSSFSheet sheet = null;
if(workbook.getSheet(sheetName)==null) {
sheet = workbook.createSheet(sheetName);
}else {
sheet = workbook.getSheet(sheetName);
}
sheet.setDefaultColumnWidth(20);
// 生成一个样式
HSSFCellStyle style = workbook.createCellStyle();
// 设置这些样式
style.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// // 生成一个字体
HSSFFont font = workbook.createFont();
// font.setColor(HSSFColor.VIOLET.index);
font.setFontHeightInPoints((short) 12);
font.setBold(true);;//HSSFFont.BOLDWEIGHT_BOLD
// // 把字体应用到当前的样式
style.setFont(font);
// 生成一个样式
HSSFCellStyle style1 = workbook.createCellStyle();
// 设置这些样式
style1.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// // 生成一个字体
HSSFFont font1 = workbook.createFont();
font1.setFontHeightInPoints((short) 12);
font1.setBold(true);
style1.setFont(font1);
style1.setAlignment(HorizontalAlignment.CENTER);
//垂直居中
style1.setVerticalAlignment(VerticalAlignment.CENTER);
/** 数字小于0的样式 */
HSSFCellStyle style2 = workbook.createCellStyle();
// 设置这些样式
style2.setAlignment(HorizontalAlignment.CENTER_SELECTION);
//垂直居中
style2.setVerticalAlignment(VerticalAlignment.CENTER);
// // 生成一个字体
HSSFFont font2 = workbook.createFont();
font2.setFontHeightInPoints((short) 14);
font2.setBold(true);
font2.setColor(HSSFColor.RED.index);
style2.setFont(font2);
/** 数字大于0的样式 */
HSSFCellStyle style3 = workbook.createCellStyle();
// 设置这些样式
//垂直居中
style3.setVerticalAlignment(VerticalAlignment.CENTER);
//水平居中
style3.setAlignment(HorizontalAlignment.CENTER_SELECTION);
// 生成一个字体
HSSFFont font3 = workbook.createFont();
font3.setFontHeightInPoints((short) 14);
font3.setBold(true);
font3.setColor(HSSFColor.GREEN.index);
style3.setFont(font3);
HSSFPatriarch patriarch = sheet.createDrawingPatriarch();
SimpleDateFormat sim = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Field[] fields = clazz.getDeclaredFields();
HSSFRow row = null;
// 只产生表格前两行标题
//第一次写入
if(currentRow==0) {
row = sheet.createRow(0);
for(Field f:fields) {
f.setAccessible(true);
ExcelFilter meta = f.getAnnotation(ExcelFilter.class);
HSSFCell cell = row.createCell(meta.sort());
cell.setCellStyle(style);
HSSFRichTextString text = new HSSFRichTextString(meta.titleName());
cell.setCellValue(text);
}
//空出第二行用于写入商品标题
currentRow=2;
}else {
//第二次递归调用,写入商品标题,会多次写,但是可以覆盖
row = sheet.createRow(1);
for(Field f:fields) {
f.setAccessible(true);
ExcelFilter meta = f.getAnnotation(ExcelFilter.class);
HSSFCell cell = row.createCell(meta.sort());
cell.setCellStyle(style);
HSSFRichTextString text = new HSSFRichTextString(meta.titleName());
cell.setCellValue(text);
}
}
int k=0;//list索引
int rowNo = currentRow;//定位到当前行的下一行
for(T o:dataset) {
row = sheet.createRow(rowNo);
for(Field f:fields) {
f.setAccessible(true);
ExcelFilter meta = f.getAnnotation(ExcelFilter.class);
HSSFCell cell = row.createCell(meta.sort());
cell.setCellStyle(style);
if(meta.isImage()) {
//图片
if(f.get(o) != null) {
try {
System.out.println("正在写入第"+rowNo+"行数据");
row.setHeight((short) (80*20));
BufferedImage input = ImageIO.read(new URL(f.get(o).toString()));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(input, "jpg", baos);
//anchor主要用于设置图片的属性
HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0, 600, 240,(short) meta.sort(), rowNo, (short) meta.sort(), rowNo);
patriarch.createPicture(anchor, workbook.addPicture(baos.toByteArray(), HSSFWorkbook.PICTURE_TYPE_JPEG));
}catch (Exception e) {
cell.setCellValue("图片生成失败");
row.setHeight((short) (20*20));
}
}else {
cell.setCellValue("无图片");
row.setHeight((short) (20*20));
}
continue;
}
if(meta.dataType().equals(CustomDataType.INTEGER)) {
//INTEGER类型
if(f.get(o) != null) {
if(f.getInt(dataset.get(k)) >= 0) {
cell.setCellStyle(style3);
cell.setCellValue(f.getInt(o));
}else {
cell.setCellStyle(style2);
cell.setCellValue(f.getInt(o));
}
}else {
cell.setCellStyle(style3);
cell.setCellValue(f.getInt(o));
}
}
if(meta.dataType().equals(CustomDataType.LONG)) {
//INTEGER类型
if(f.get(o) != null) {
if(f.getLong(dataset.get(k)) >= 0) {
cell.setCellStyle(style3);
cell.setCellValue(f.getLong(o));
}else {
cell.setCellStyle(style2);
cell.setCellValue(f.getLong(o));
}
}else {
cell.setCellStyle(style3);
cell.setCellValue(f.getLong(o));
}
}
if(meta.dataType().equals(CustomDataType.DOUBLE)) {
//DOUBLE类型
if(f.get(o) != null) {
if(f.getDouble(dataset.get(k)) >= 0) {
cell.setCellStyle(style3);
cell.setCellValue(f.getDouble(o));
}else {
cell.setCellStyle(style2);
cell.setCellValue(f.getDouble(o));
}
}else {
cell.setCellStyle(style3);
cell.setCellValue(f.getDouble(o));
}
}
if(meta.dataType().equals(CustomDataType.STRING)) {
//string类型
cell.setCellStyle(style1);
if(f.get(o) != null) {
cell.setCellValue(f.get(o).toString());
}else {
cell.setCellValue("");
}
}
if(meta.dataType().equals(CustomDataType.DATE)) {
//DATE类型
cell.setCellStyle(style1);
if(f.get(o) != null) {
cell.setCellValue(sim.format(f.get(o)));
}else {
cell.setCellValue("");
}
}
if(meta.dataType().equals(CustomDataType.LIST)) {
//List类型
rowNo++;
if(f.get(o)!=null) {
rowNo = writeListData(rowNo,workbook,outStream,f,o,sheetName);
}
}
}
k++;
rowNo++;
}
workbook.write(outStream);
}
@SuppressWarnings("unchecked")
public <T> int writeListData(int rowNo,HSSFWorkbook Wworkbook,ByteArrayOutputStream outStream,Field f,T o,String sheetName) {
Class<T> genericClazz= null;
//获取list集合递归写数据
Type genericType = f.getGenericType();
if(genericType!=null && (genericType instanceof ParameterizedType)) {
//带泛型的list集合
ParameterizedType pt = (ParameterizedType) genericType;
//获取到泛型的class
genericClazz = (Class<T>)pt.getActualTypeArguments()[0];
}
List<T> l = null;
try {
l = (List<T>)f.get(o);
exportExcel(l,genericClazz,Wworkbook,outStream,sheetName,rowNo);
// return rowNo+l.size();
return rowNo+l.size()-1;
} catch (Exception e) {
return rowNo;
}
}
}
自定义注解及其应用
//注解类
@Target({
ElementType.METHOD,ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ExcelFilter {
String titleName() default "";//标题名
int sort() default 0;//顺序
boolean isImage() default false;//是否是图片
CustomDataType dataType() default CustomDataType.STRING;//属性的类型
}
//枚举类
public enum CustomDataType {
DOUBLE("double"),INTEGER("int"),STRING("string"),DATE("date"),LONG("long"),LIST("list");
// 成员变量
private String index;
// 构造方法
private CustomDataType(String index) {
this.index = index;
}
public String getIndex() {
return index;
}
public void setIndex(String index) {
this.index = index;
}
}
//数据集合类应用
public class TaskOrderAndItemHistoryExcel {
@ExcelFilter(titleName="订单编号",sort=0,dataType=CustomDataType.STRING,isImage=false)
private String platformOrderId;
@ExcelFilter(titleName="仓库",sort=5,dataType=CustomDataType.STRING,isImage=false)
private String stockWarehouse;
@ExcelFilter(titleName="订单时间",sort=8,dataType=CustomDataType.DATE,isImage=false)
private Date orderTime;
@ExcelFilter(titleName="物流公司",sort=17,dataType=CustomDataType.STRING,isImage=false)
private String myLogistics;
@ExcelFilter(titleName="",sort=18,dataType=CustomDataType.LIST,isImage=false)
private List<TbTaskItemHistoryExcel> items;//商品集合
//还有很多属性,这里出于商业原因不展示所有......
}
三.原理
原理啥的其实也没啥高深的东西,就是最基础的反射嘛;通过反射我们可以获取目标对象属性的注解,注解包括sort(这个属性对应的单元格的第几列),dataType(属性的数据类型),之所以对属性的数据类型写一个枚举,是为了防止因为出现int和Integer这种类型,因为不知道程序员会用哪个,所以干脆用枚举把他给定死;titleName(属性对应的标题行);isIamge(对于需要写入的图片需要做特殊的处理,这里单独列出来作为boolean判断).
这里比较特殊的是,我们的数据类型里多了一个List类型,考虑到我们反射时,嵌套List做的操作其实都是一样的,逐个字段去反射,然后循环直达结束,所以,很容易就会想到通过递归算法来进行反射.
递归算法反射时,需要注意的几点问题:
[1]为了使我们嵌套List中的内容和原List中的内容写入同一张表中,并且是连续写入,我们需要传入的参数就有workbook,sheetName,保证递归调用时操作的是同一个工作簿里的同一张表
[2]没次执行递归调用结束后,会调用write将outputStream中的内容写入表格,再次递归写入时如果不重置流,会导致之前写入的内容被覆盖,所以我们这里在进入方法时便会重置输出流 outStream.reset()
想分享的到这里就结束了,其他方面的问题,大部分我都在代码中注释说明了,所以认真看完的话应该是完全没有问题了的.
也许这种方法已经有很多大佬用过了,第一次发博客,我只能说小弟不才,我只是把自己接触到的这些比较好的东西拉出来分享总结一下,并没有打算说是要教大家怎样怎样,暂时还没那个本领,也欢迎大佬们一起在评论区讨论更多更高明的解决方案,秉着学习交流的目的,一起进步,一起成长,谢谢!!