Java中的EasyExcel工具類如何使用？附詳細(xì)內(nèi)容解析

 private CommonService commonService;
    public void importExcel(MultipartFile file) throws IOException {
    // HEAD_ROW_NUMBER為Excel中的頭部行數(shù), 這里的關(guān)于ImportExcelListener的構(gòu)造方法中HEAD_ROW_NUMBER參數(shù)可以根據(jù)需要決定傳或者不傳
        EasyExcel.read(file.getInputStream(), StudentVo.class, new ImportExcelListener<StudentVo>(HEAD_ROW_NUMBER, commonService)).sheet().headRowNumber(HEAD_ROW_NUMBER).doRead();
    }

public class ImportExcelListener<T> extends AnalysisEventListener<T> {
        /**
         * 每隔BATCH_COUNT條存儲(chǔ)數(shù)據(jù)庫(kù) 然后清理list ，方便內(nèi)存回收
         */
        private static final int BATCH_COUNT = 500;
        private int headRowNum;
        private CommonService commonService;
        private List<T> list = new ArrayList<>();

        public ImportExcelListener(int headRowNumber, CommonService commonService) {
            this.headRowNum = headRowNumber;
            this.commonService = commonService;
        }

        /**
         * 這個(gè)每一條數(shù)據(jù)解析都會(huì)來調(diào)用
         */
        @Override
        public void invoke(T data, AnalysisContext context) {
            // 這里也可以將data轉(zhuǎn)為對(duì)應(yīng)實(shí)體, 然后做一些參數(shù)校驗(yàn)
            Integer rowNum = context.readRowHolder().getRowIndex();
           log.info("當(dāng)前解析的數(shù)據(jù)為第{}行", rowNum);
          
            list.add(data);
            // 批量保存, 防止一次性數(shù)據(jù)過多, 內(nèi)存溢出
            if (list.size() >= BATCH_COUNT) {
                // 保存
                commonService.save(list);
                list.clear();
            }
        }


        // 在解析之后, 也要記得再判斷是否為空, 不為空要保存一下
        @Override
        public void doAfterAllAnalysed(AnalysisContext context) {
            if (CollectionUtils.isEmpty(list)) {
                return;
            }
            commonService.save(list);
            list.clear();
        }
    }

List<Object> data = null;
        try {
            data = EasyExcelFactory.read(file.getInputStream()).sheet().doReadSync();
        } catch (IOException e) {
            log.error("讀取失敗", e);
            throw new BusinessException("讀取失敗");
        }
        // 保存操作
        // ...

public void test() throws FileNotFoundException {
        File file = new File("E:\work-grandview\測(cè)試.xlsx");
        // 創(chuàng)建writerBuilder對(duì)象，自動(dòng)調(diào)整列寬
        ExcelWriter excelWriter = EasyExcel.write(new FileOutputStream(file))
                .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
                .autoCloseStream(Boolean.TRUE)
                .build();

        //  List<List<?>>類型, 二維數(shù)據(jù), 表示第幾行第幾列, 設(shè)置表頭內(nèi)容
        List<List<String>> titleList = new ArrayList<>();
        titleList.add(Arrays.asList("名稱", "key", "value"));
        int sheetNum = 0;
        WriteSheet writeSheet = EasyExcel.writerSheet(sheetNum,"導(dǎo)出數(shù)據(jù)").build();
        excelWriter.write(titleList, writeSheet);

        // 生成導(dǎo)出內(nèi)容;
        List<List<Object>> content = new ArrayList<>();
        // 10行3列
        for (int i = 0; i < 10; i++) {
            List<Object> dataList = new ArrayList<>();
            for (int j = 0; j < 3; j++) {
                dataList.add(j);
            }
            content.add(dataList);
        }


        // 寫入文件
        excelWriter.write(content, writeSheet);
        // 關(guān)閉文件流
        excelWriter.finish();
    }

@Data
 public class VO {
        @ExcelProperty(value = "姓名", index = 0)
        int name;
        @ExcelProperty(value = "key", index = 1)
        int key;
        @ExcelProperty(value = "value", index = 2)
        int value;
    }

@Test
    public void test() throws FileNotFoundException {
        File file = new File("E:\work-grandview\測(cè)試.xlsx");
        // 創(chuàng)建writerBuilder對(duì)象，自動(dòng)調(diào)整列寬
        ExcelWriter excelWriter = EasyExcel.write(new FileOutputStream(file))
                .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
                .autoCloseStream(Boolean.TRUE)
                .build();

        // 生成導(dǎo)出內(nèi)容;
        List<VO> content = new ArrayList<>();
        // 10行3列
        for (int i = 0; i < 10; i++) {
            VO vo = new VO();
            vo.setKey(i);
            vo.setName(i);
            vo.setValue(i);
           content.add(vo);
        }
		// 創(chuàng)建sheet, 設(shè)置0號(hào)表, 實(shí)際運(yùn)用中可能得創(chuàng)建多張, 可以遍歷數(shù)據(jù), 每滿足n條就創(chuàng)建i號(hào)sheet表
        WriteSheet writeSheet = EasyExcel.writerSheet(0,"導(dǎo)出數(shù)據(jù)").build();
        // 設(shè)置表頭
        writeSheet.setClazz(content.get(0).getClass());
        // 寫入文件
        excelWriter.write(content, writeSheet);
        excelWriter.finish();

    }