文件名注解，参数为文件名，可以选择增加日期后缀，作用在要导出是实体类上
@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface FileName {// 前缀String value();// 是否加日期后缀boolean addDate() default false;// 日期后缀String pattern() default "yyyy-MM-dd";}
文件头注解，参数有标题名，当某些值是日期类型时可以进行格式化，作用在要导出是实体类里面的具体属性上
@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface FileHeader {// 标题String value();// 日期类型数据格式化String pattern() default "yyyy-MM-dd HH:mm:ss";}
CSV分页导出，先进行实例化，参数有http返回和带有注解的实体类，分批调用export写入数据
public class CsvPageExport<T> {private HttpServletResponse response;private Pair<List<FileHeader>, List<Field>> headerField;public CsvPageExport(HttpServletResponse response, Class<T> clazz) {this.response = response;this.headerField = ExportUtil.getHeaderField(clazz);ExportUtil.writeCsvResponse(response, ExportUtil.getFileName(clazz));ExportUtil.writeCsv(response, ExportUtil.getHeader(headerField.getLeft()));}public void export(List<T> dataList) {ExportUtil.writeCsv(response, ExportUtil.getValue(dataList, headerField));}}
EXCEL多SHEET对象，属性有sheet名字和它里面的具体数据集合
public class SheetData<T> {private String sheetName;private List<T> dataList = new ArrayList<>();public String getSheetName() {return sheetName;}public SheetData<T> setSheetName(String sheetName) {this.sheetName = sheetName;return this;}public List<T> getDataList() {return dataList;}public SheetData<T> setDataList(List<T> dataList) {this.dataList = dataList;return this;}}
具体实现逻辑，主要有注解导出EXCEL，注解导出多SHEET的EXCEL，注解导出CSV
public class ExportUtil {private static final Logger LOGGER = LoggerFactory.getLogger(ExportUtil.class);private static final String EMPTY_FILE_NAME = "空文件";/*** 注解导出EXCEL*/public static void excel(HttpServletResponse response, List<?> dataList) {Triple<String, String[], List<String[]>> nameHeaderValue = getNameHeaderValue(dataList);Workbook workbook = new XSSFWorkbook();Sheet sheet = workbook.createSheet();writeExcel(workbook, sheet, nameHeaderValue.getMiddle(), nameHeaderValue.getRight());writeExcelResponse(response, nameHeaderValue.getLeft(), workbook);}/*** 注解导出多SHEET的EXCEL*/public static <T> void multiSheetExcel(HttpServletResponse response, List<SheetData<T>> sheetDataList) {multiSheetExcel(response, sheetDataList, getDefaultFileName(sheetDataList));}/*** 注解导出多SHEET的EXCEL*/public static <T> void multiSheetExcel(HttpServletResponse response, List<SheetData<T>> sheetDataList, String fileName) {Workbook workbook = new XSSFWorkbook();for (SheetData<T> sheetData : sheetDataList) {String sheetName = sheetData.getSheetName();Sheet sheet = StringUtils.isBlank(sheetName) ? workbook.createSheet() : workbook.createSheet(sheetName);Pair<String[], List<String[]>> headerValue = getHeaderValue(sheetData.getDataList());writeExcel(workbook, sheet, headerValue.getLeft(), headerValue.getRight());}writeExcelResponse(response, fileName, workbook);}/*** 注解导出CSV*/public static void csv(HttpServletResponse response, List<?> dataList) {Triple<String, String[], List<String[]>> nameHeaderValue = getNameHeaderValue(dataList);writeCsvResponse(response, nameHeaderValue.getLeft());writeCsv(response, nameHeaderValue.getMiddle());writeCsv(response, nameHeaderValue.getRight());}protected static void writeExcel(Workbook workbook, Sheet sheet, String[] header, List<String[]> value) {XSSFCellStyle cellStyle = (XSSFCellStyle) workbook.createCellStyle();createRow(sheet, 0, header, cellStyle);for (int i = 0; i < value.size(); i++) {createRow(sheet, i + 1, value.get(i), cellStyle);}}protected static <T> String getDefaultFileName(List<SheetData<T>> sheetDataList) {if (CollectionUtils.isEmpty(sheetDataList)) {return EMPTY_FILE_NAME;}T data = null;for (SheetData<T> sheetData : sheetDataList) {for (T o : sheetData.getDataList()) {data = o;break;}}if (data == null) {return EMPTY_FILE_NAME;}return getFileName(data.getClass());}protected static void writeExcelResponse(HttpServletResponse response, String fileName, Workbook workbook) {response.setContentType("application/vnd.ms-excel;charset=UTF-8");String filename;try {filename = URLEncoder.encode(fileName + ".xlsx", "UTF-8");} catch (UnsupportedEncodingException e) {filename = System.currentTimeMillis() + ".xlsx";}response.setHeader("Content-Disposition", "attachment; filename=" + filename);try {OutputStream out = response.getOutputStream();workbook.write(out);} catch (IOException e) {LOGGER.error("{} export exception", filename, e);}}protected static void createRow(Sheet sheet, int row, String[] cellValues, CellStyle cellStyle) {Row iRow = sheet.createRow(row);for (int i = 0; i < cellValues.length; i++) {Cell cell = iRow.createCell(i);cell.setCellStyle(cellStyle);cell.setCellValue(cellValues[i]);}}protected static void writeCsvResponse(HttpServletResponse response, String fileName) {response.setContentType("text/csv;charset=UTF-8");String filename;try {filename = URLEncoder.encode(fileName + ".csv", "UTF-8");} catch (UnsupportedEncodingException e) {filename = System.currentTimeMillis() + ".csv";}response.setHeader("Content-Disposition", "attachment; filename=" + filename);try {response.getOutputStream().write(new byte[]{(byte) 0xEF, (byte) 0xBB, (byte) 0xBF});response.getOutputStream().flush();} catch (IOException e) {LOGGER.error("write CSV add BOM head error", e);}}protected static void writeCsv(HttpServletResponse response, String data) {try {response.getOutputStream().write((data + "\n").getBytes(StandardCharsets.UTF_8));response.getOutputStream().flush();} catch (IOException e) {LOGGER.error("write CSV error", e);}}protected static void writeCsv(HttpServletResponse response, String[] data) {StringBuilder stringBuilder = new StringBuilder();for (String e : data) {if (stringBuilder.length() > 0) {stringBuilder.append(",");}stringBuilder.append(e.replace(",", " "));}writeCsv(response, stringBuilder.toString());}protected static void writeCsv(HttpServletResponse response, List<String[]> data) {for (String[] arr : data) {writeCsv(response, arr);}}protected static Triple<String, String[], List<String[]>> getNameHeaderValue(List<?> dataList) {if (CollectionUtils.isEmpty(dataList)) {return Triple.of(EMPTY_FILE_NAME, new String[0], Collections.<String[]>emptyList());}Pair<String[], List<String[]>> pair = getHeaderValue(dataList);return Triple.of(getFileName(dataList.get(0).getClass()), pair.getLeft(), pair.getRight());}protected static Pair<String[], List<String[]>> getHeaderValue(List<?> dataList) {if (CollectionUtils.isEmpty(dataList)) {return Pair.of(new String[0], Collections.<String[]>emptyList());}Pair<List<FileHeader>, List<Field>> headerField = getHeaderField(dataList.get(0).getClass());return Pair.of(getHeader(headerField.getLeft()), getValue(dataList, headerField));}protected static List<String[]> getValue(List<?> dataList, Pair<List<FileHeader>, List<Field>> headerField) {if (CollectionUtils.isEmpty(dataList) || headerField == null) {return Collections.emptyList();}List<String[]> value = new ArrayList<>(dataList.size());for (Object data : dataList) {String[] temp = new String[headerField.getLeft().size()];for (int index = 0; index < headerField.getLeft().size(); index++) {try {temp[index] = getData(headerField.getLeft().get(index), headerField.getRight().get(index).get(data));} catch (Exception e) {LOGGER.error("get value error.", e);temp[index] = "【error】";}}value.add(temp);}return value;}protected static Pair<List<FileHeader>, List<Field>> getHeaderField(Class<?> clazz) {Field[] fields = clazz.getDeclaredFields();List<FileHeader> headerList = new ArrayList<>(fields.length);List<Field> fieldList = new ArrayList<>(fields.length);for (Field field : fields) {FileHeader fileHeader = field.getAnnotation(FileHeader.class);if (fileHeader == null) {continue;}field.setAccessible(true);headerList.add(fileHeader);fieldList.add(field);}return Pair.of(headerList, fieldList);}protected static String getData(FileHeader header, Object o) {if (o == null) {return "";}return o instanceof Date ? DateFormatUtils.format((Date) o, header.pattern()) : String.valueOf(o);}protected static String getFileName(Class<?> clazz) {FileName fileName = clazz.getAnnotation(FileName.class);if (fileName == null) {return "";}return fileName.addDate() ? fileName.value() + DateFormatUtils.format(new Date(), fileName.pattern()) : fileName.value();}protected static String[] getHeader(Class<?> clazz) {return getHeader(getHeaderField(clazz).getLeft());}protected static String[] getHeader(List<FileHeader> headerList) {String[] header = new String[headerList.size()];int i = 0;for (FileHeader fileHeader : headerList) {header[i] = fileHeader.value();i++;}return header;}}
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