easyexcel使用模板填充excel坑点总结

1.单层map设置值是{属性}，那使用两层map进行设置值，是不是可以使用{属性.属性}，以为取出map里字段只用{属性}就可以设置值，那再加个.就可以从里边map取出对应属性，没有两层map写法
填充得到的文件打开报错 was empty (zero bytes long)

Map<String, Map<String, String>> map = new HashMap<>();
    Map<String, String> map1 = new HashMap<>();
    map1.put("name", "张三");
    map1.put("age", "18");
    HashMap<String, String> map2 = new HashMap<>();
    map2.put("name", "李四");
    map2.put("age", "19");
    map.put("obj1", map1);
    map.put("obj2", map2);
    ExcelWriter excelWriter = EasyExcel.write(EXCEL_OUPUT_FILE_PATH)
        .withTemplate(TEMPLATE_FILE_PATH).build(); // 构建ExcelWriter对象 整个文件对象
    WriteSheet sheet1 = EasyExcel.writerSheet("Sheet1").build(); // 构建sheet对象
    excelWriter.fill(map, sheet1); //将操作的sheet和数据填充到ExcelWriter对象中

2.尝试使用map包对象写法，想着反正是.，那里面是对象就可以使用了吧，填充后文件还是报文件 was empty (zero bytes long)

public static final String EXCEL_OUPUT_FILE_PATH = "templateOutput/template1Output.xlsx";
  public static final String TEMPLATE_FILE_PATH = "excelTemplate/template1.xlsx";

  static class Person {

    public String name;
    public String age;
  }

  public static void main(String[] args) {
    Map<String, Person> map = new HashMap<>();
    Map<String, String> map1 = new HashMap<>();
    Person person = new Person();
    person.name = "张三";
    person.age = "18";
    map1.put("name", "张三");
    map1.put("age", "18");
    HashMap<String, String> map2 = new HashMap<>();
    Person person1 = new Person();
    person1.name = "李四";
    person1.age = "19";
    map2.put("name", "李四");
    map2.put("age", "19");
    map.put("obj1", person);
    map.put("obj2", person1);
    ExcelWriter excelWriter = EasyExcel.write(EXCEL_OUPUT_FILE_PATH)
        .withTemplate(TEMPLATE_FILE_PATH).build(); // 构建ExcelWriter对象 整个文件对象
    WriteSheet sheet1 = EasyExcel.writerSheet("Sheet1").build(); // 构建sheet对象
    excelWriter.fill(map, sheet1); //将操作的sheet和数据填充到ExcelWriter对象中

  }

3.使用创建EasyWriter和WriteSheet对象，直接使用
EasyExcel.write(filePath).withTemplate(excelTemplate).sheet(0).doFill(excelDataMap);

EasyExcel.write(filePath).withTemplate(excelTemplate).sheet(1).doFill(excelDataMap);

对两个sheet进行填充，只有最后一个sheet设置了值。
应该创建EasyWriter和WriterSheet对象进行设置值

正确写法：

Map<String, String> excelDataMap = new HashMap();
ExcelWriter excelWriter = EasyExcel.write(filePath).withTemplate(asInputStream).build();
WriteSheet sheet1 = EasyExcel.writerSheet(0).build();
WriteSheet sheet2 = EasyExcel.writerSheet(0).build();
excelWriter.fill(sheet1, excelDataMap);
excelWriter.fill(sheet2, excelDataMap);
excelWriter.finish();

4.使用，没有告诉excelwriter对象，结束导入，导致生成的excel文件打不开，报was empty (zero bytes long)。应该在写入完成后调用

excelWriter.finish();

完整用法：

Map<String, String> excelDataMap = new HashMap();
ExcelWriter excelWriter = EasyExcel.write(filePath).withTemplate(asInputStream).build();
WriteSheet sheet1 = EasyExcel.writerSheet(0).build();
WriteSheet sheet2 = EasyExcel.writerSheet(0).build();
excelWriter.fill(sheet1, excelDataMap);
excelWriter.fill(sheet2, excelDataMap);
excelWriter.finish();

5.由于我需要将模版文件的某些sheet复制多个形成新的模版，但又不想多产生一个模版文件，我将输出文件和文件和模版文件都设置成一个

ExcelWriter excelWriter = EasyExcel.write(TEMPLATE_FILE_PATH).withTemplate(TEMPLATE_FILE_PATH)
        .build();

报错Exception in thread "main" com.alibaba.excel.exception.ExcelGenerateException: Create workbook failure
   at com.alibaba.excel.context.WriteContextImpl.<init>(WriteContextImpl.java:98)
   at com.alibaba.excel.write.ExcelBuilderImpl.<init>(ExcelBuilderImpl.java:36)
   at com.alibaba.excel.ExcelWriter.<init>(ExcelWriter.java:36)
   at com.alibaba.excel.write.builder.ExcelWriterBuilder.build(ExcelWriterBuilder.java:114)
   at org.example.demotask.util.EasyexcelUtils.main(EasyexcelUtils.java:60)
Caused by: org.apache.poi.EmptyFileException: The supplied file was empty (zero bytes long)
复制模版里的sheet形成新的模版赋值导出写法：

Map<String, String> map = new HashMap();
      Map<String, Map<String, String>> lotMap = new HashMap();
      //获取的模板文件位置
      String excelTemplate = "path";
      FileInputStream fileInputStream = new FileInputStream(excelTemplate);
      InputStream templateStream = fileInputStream;
      Workbook workbook = WorkbookFactory.create(templateStream);
      List<String> fatherSheet = Lists.newArrayList("Sheet1");
      ArrayList<String> lotNames = new ArrayList<>(lotMap.keySet());
       //复制sheet
      for (String cloneSheet : fatherSheet) {
        for (String lotName : lotNames) {
            //根据要复制的sheet名拿到要复制的sheet
          Sheet templateSheet = workbook.getSheet(cloneSheet);
          Sheet newSheet = workbook.cloneSheet(workbook.getSheetIndex(templateSheet));
          int newSheetIndex = workbook.getSheetIndex(newSheet);  // 获取新克隆的 sheet 索引
            //设置复制的sheet名
          workbook.setSheetName(newSheetIndex, cloneSheet + "(" + lotName + ")");
        }
      }
       //新建内存输出流，作为新的模版文件输出
      ByteArrayOutputStream ops = new ByteArrayOutputStream();
      workbook.write(ops);
      ops.flush();
      byte[] byteArray = ops.toByteArray();
      ops.close();
      workbook.close();
      //使用新的文件的字节流作为模板文件输入
      InputStream asInputStream = new ByteArrayInputStream(byteArray);
      // 原文件流后续已不使用，此处关闭
      templateStream.close();
      ops.close();
      ExcelWriter excelWriter = EasyExcel.write("D:\\newnewnewFormat111.xlsx").withTemplate(asInputStream).build();
      WriteSheet mainSheet = EasyExcel.writerSheet("Sheet1").build();
      excelWriter.fill(map, mainSheet);
      for (String lotName : lotNames) {
        WriteSheet sheet = EasyExcel.writerSheet("Sheet1(" + lotName + ")").build();
        excelWriter.fill(lotMap.get(lotName), sheet);
      }
       //重要 使用excelWriter写入完一定要调用finish方法，不然文件打不开
      excelWriter.finish();

总结：
1.使用Map类型进行填充只有能普通类型
2.模板注意用{} 来表示你要用的变量如果本来就有"{","}" 特殊字符用"\{","\}"代替
3. {} 代表普通变量 {.} 代表是list的变量 {前缀.} 前缀可以区分不同的list

WriteSheet writeSheet = EasyExcel.writerSheet().build();
              List<String> list1 = new ArrayList<>();
              list1.add("张三");
              list1.add("李四");
              ArrayList<String> list2 = new ArrayList<>();
              list2.add("11");
              list2.add("22");
               //设置列表展开方向，默认垂直
            FillConfig fillConfig = FillConfig.builder().direction(WriteDirectionEnum.HORIZONTAL).build();
            // 如果有多个list 模板上必须有{前缀.} 这里的前缀就是 data1，然后多个list必须用 FillWrapper包裹
            excelWriter.fill(new FillWrapper("data1", list1), fillConfig, writeSheet);
            excelWriter.fill(new FillWrapper("data2", list1), writeSheet);

4.使用ExcelWriter进行sheet写入时完成时，最好调用ExcelWriter对象的finish()方法，不然可能出现文件损坏的情况

5.模版文件路径不要跟输出文件路径，如果不想输出临时的模版文件，可以将产生新的写入内存流，然后将内存流的字节数据写入字节输入流作为模板输入

    String excelTemplate = "path";
      FileInputStream fileInputStream = new FileInputStream(excelTemplate);
      InputStream templateStream = fileInputStream;
      Workbook workbook = WorkbookFactory.create(templateStream);
      List<String> fatherSheet = Lists.newArrayList("Sheet1");
      ArrayList<String> lotNames = new ArrayList<>(lotMap.keySet());
       //复制sheet
      for (String cloneSheet : fatherSheet) {
        for (String lotName : lotNames) {
            //根据要复制的sheet名拿到要复制的sheet
          Sheet templateSheet = workbook.getSheet(cloneSheet);
          Sheet newSheet = workbook.cloneSheet(workbook.getSheetIndex(templateSheet));
          int newSheetIndex = workbook.getSheetIndex(newSheet);  // 获取新克隆的 sheet 索引
            //设置复制的sheet名
          workbook.setSheetName(newSheetIndex, cloneSheet + "(" + lotName + ")");
        }
      }
       //新建内存输出流，作为新的模版文件输出
      ByteArrayOutputStream ops = new ByteArrayOutputStream();
      workbook.write(ops);
      ops.flush();
      byte[] byteArray = ops.toByteArray();
      ops.close();
      workbook.close();
      //使用新的文件的字节流作为模板文件输入
      InputStream asInputStream = new ByteArrayInputStream(byteArray);
      // 原文件流后续已不使用，此处关闭
      templateStream.close();
      ops.close();
      ExcelWriter excelWriter = EasyExcel.write("D:\\newnewnewFormat111.xlsx").withTemplate(asInputStream).build();

6.使用EasyExcel.write(fileName).withTemplate(templateFileName).sheet().doFill(map);进行填充会出现只有最后一个sheet填充成功，如果想对多个sheet进行填充，要使用ExcelWriter对象操作数据和sheet对象。