根据现有代码进行M种分类组合使用N个模板的方式生成Excel文档

[qq272936993]

ExcelHelper不能继承的情况下,当然可以有修改源码的方式,我使用了以下方式,不知道有没什么更好的办法

`

public class ExcelExpandHelper {

private static volatile ExcelExpandHelper mExcelExpandHelper;

//实现单模板,多sheet的方式
private ExcelExpandHelper() {

}

public static ExcelExpandHelper getInstance() {
    if (null == mExcelExpandHelper) {
        synchronized(ExcelExpandHelper.class) {
            if (null == mExcelExpandHelper) {
                mExcelExpandHelper = new ExcelExpandHelper();
            }
        }
    }

    return mExcelExpandHelper;
}

public void normalSheet2Excel(List<NormalSheetExpandWrapper> sheetWrappers, String templatePath, OutputStream os ) throws Excel4JException {
    try {
        SheetTemplate sheetTemplate = this.exportExcelByModuleHandler(templatePath, sheetWrappers);
        Throwable var5 = null;

        try {
            sheetTemplate.write2Stream(os);
        } catch (Throwable var15) {
            var5 = var15;
            throw var15;
        } finally {
            if (sheetTemplate != null) {
                if (var5 != null) {
                    try {
                        sheetTemplate.close();
                    } catch (Throwable var14) {
                        var5.addSuppressed(var14);
                    }
                } else {
                    sheetTemplate.close();
                }
            }

        }
    } catch (IOException | Excel4JException var17) {
        throw new Excel4JException(var17);
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    }
}


private SheetTemplate exportExcelByModuleHandler(String templatePath, List<NormalSheetExpandWrapper> sheets) throws Excel4JException, NoSuchFieldException {
    //读取模板文件
    SheetTemplate template = SheetTemplateHandler.sheetTemplateBuilder(templatePath);
    //克隆模板
    cloneSheet(template , sheets);
    //这是用户配置的有多少sheet
    Iterator var4 = sheets.iterator();
    while(var4.hasNext()) {
        NormalSheetExpandWrapper sheet = (NormalSheetExpandWrapper)var4.next();
        //生成sheet
        this.generateSheet(sheet.getSheetIndex() , sheet.getData(), sheet.getExtendMap(), sheet.getClazz(), sheet.isWriteHeader(), template);
    }

    return template;
}

private void generateSheet(int sheetIndex ,List<?> data, Map<String, String> extendMap, Class clazz, boolean isWriteHeader, SheetTemplate template) throws Excel4JException, NoSuchFieldException {
    //加载模板
    SheetTemplateHandler.loadTemplate(template, sheetIndex);
    //将值设置到模板中
    SheetTemplateHandler.extendData(template, extendMap);

    //设置标题
    List<ExcelHeader> headers = Utils.getHeaderList(clazz);
    Iterator var8;
    //如果需要重新构建header
    if (isWriteHeader) {
        SheetTemplateHandler.createNewRow(template);
        var8 = headers.iterator();

        while(var8.hasNext()) {
            ExcelHeader header = (ExcelHeader)var8.next();
            SheetTemplateHandler.createCell(template, header.getTitle(), (String)null);
        }
    }

    var8 = data.iterator();

    while(var8.hasNext()) {
        Object object = var8.next();
        SheetTemplateHandler.createNewRow(template);
        SheetTemplateHandler.insertSerial(template, (String)null);
        Iterator var10 = headers.iterator();

        while(var10.hasNext()) {
            ExcelHeader header = (ExcelHeader)var10.next();
            SheetTemplateHandler.createCell(template, Utils.getProperty(object, header.getFiled(), header.getWriteConverter()), (String)null);
        }
    }

}

/***
 * 使用反射的原理
 * */
private void cloneSheet(SheetTemplate template ,  List<NormalSheetExpandWrapper> sheets) throws NoSuchFieldException {
    Class cls = template.getClass();
    Field field = cls.getDeclaredField("workbook");
    try {
        field.setAccessible(true);
        Workbook workbook = (Workbook) field.get(template);
        Iterator<Sheet> it = workbook.sheetIterator();
        int len = 0;
        Sheet defSheet = null;
        while(it.hasNext()){
            Sheet sheet = it.next();
            if(len == 0){
                defSheet = sheet;
            }
            len ++;
        }

        int sheetSize = sheets.size();
        //有模板文件后,进行克隆
        if(defSheet != null){
            Set<Integer> usedIndexSet = new HashSet<>();
            for(int i = 0; i < sheetSize ; i++){
                NormalSheetExpandWrapper normalSheetExpandWrapper = sheets.get(i);
                //这里需要判断是getSheet还是cloneSheet(第一次使用为get,否则为clone)
                Integer cloneIndexSheet = normalSheetExpandWrapper.getCloneIndexSheet();
                Sheet sheet = null;
                if(usedIndexSet.contains(cloneIndexSheet)){
                    sheet = workbook.cloneSheet(cloneIndexSheet);
                }else{
                    sheet = workbook.getSheetAt(cloneIndexSheet);
                     usedIndexSet.add(cloneIndexSheet);
                }

                workbook.setSheetOrder(sheet.getSheetName() , i);
                String sheetName = normalSheetExpandWrapper.getSheetName();
                workbook.setSheetName(i , sheetName);
            }
        }
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
}

  }

`