EasyExcel使用

一. EasyExcel简介

1. 数据导入
2. 数据导出: 统计信息归档
3. 数据传输：异构系统之间数据传输

二. EasyExcel特点

1. asyExcel是阿里巴巴开源的一个excel处理框架，以使用简单、节省内存著称。EasyExcel能大大减少占用内存的主要原因是在解析Excel时没有将文件数据一次性全部加载到内存中，而是从磁盘上一行行读取数据，逐个解析。
2. EasyExcel采用一行一行的解析模式，并将一行的解析结果以观察者的模式通知处理（AnalysisEventListener）

三. EasyExcel使用

1. 导入依赖

   <dependency>
           <groupId>com.alibabagroupId>
   		<artifactId>easyexcelartifactId>
   		<version>2.1.1version>
   	dependency>
   

2. 创建实体类

   @Data
   public class Stu {
   
       //设置表头名称
       @ExcelProperty("学生编号")
       private int sno;
       
       //设置表头名称
       @ExcelProperty("学生姓名")
       private String sname;
   }
   

3. 写入方法一

   public static void main(String[] args) throws Exception{
           String filename = "F:\\document\\excel_test.xlsx";
           EasyExcel.write(filename, Stu.class).sheet("写入方法一")
                   .doWrite(data());
       }
       private static List<Stu> data(){
           List<Stu> list = new ArrayList<>();
           for (int i = 0; i < 10; i++) {
               Stu data = new Stu();
               data.setSno(i);
               data.setSname("鸡你太美"+i);
               list.add(data);
           }
           return list;
       }
   

4. 写入方法二

   public static void main(String[] args) {
           String filename = "F:\\document\\excel_test.xlsx";
           ExcelWriter excelWriter = EasyExcel.write(filename, Stu.class).build();
           WriteSheet writeSheet = EasyExcel.writerSheet("写入方法二").build();
           excelWriter.write(data(),writeSheet);
           excelWriter.finish();
       }
   

5. 读操作的监听器类

   public class ExcelListener extends AnalysisEventListener<Stu> {
       List<Stu> list = new ArrayList<>();
       @Override
       public void invoke(Stu user, AnalysisContext analysisContext) {
           System.out.println("User"+user);
           list.add(user);
       }
   
       @Override
       public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
           System.out.println("表头信息"+headMap);
       }
   
       @Override
       public void doAfterAllAnalysed(AnalysisContext analysisContext) {
   
       }
   }
   

6. 读取类

   public class ExcelRead {
       public static void main(String[] args) {
           String filename = "F:\\document\\excel_test.xlsx";
           EasyExcel.read(filename, Stu.class, new ExcelListener()).sheet().doRead();
   
       }
   }
   

7. 写入多个工作表

    public static void main(String[] args) {
           String filename = "F:\\document\\excel_test2.xlsx";
           ExcelWriter excelWriter = EasyExcel.write(filename,Stu.class).build();
   
           WriteSheet writeSheet1 = EasyExcel.writerSheet(0,"学生一").head(Stu.class).build();
           WriteSheet writeSheet2 = EasyExcel.writerSheet(1,"学生二").head(Stu.class).build();
   
           excelWriter.write(data(),writeSheet1);
           excelWriter.write(data(),writeSheet2);
           excelWriter.finish();
       }
   

四. 字典导出功能

1. 创建实体类，属性上加@ExcelProperty(value,index)

2. service

   service extends ISerivce<Dict>{
       void exportData(HttpServletResponse response);
   }
   实现类
   @Override
       public void exportData(HttpServletResponse response) {
           try {
               response.setContentType("application/vnd.ms-excel");
               response.setCharacterEncoding("utf-8");
               // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
               String fileName = URLEncoder.encode("数据字典", "UTF-8");
               response.setHeader("Content-disposition", "attachment;filename="+ fileName + ".xlsx");
   
               List<Dict> dictList = baseMapper.selectList(null);
               List<DictEeVo> dictVoList = new ArrayList<>(dictList.size());
               for(Dict dict : dictList) {
                   DictEeVo dictVo = new DictEeVo();
                   BeanUtils.copyProperties(dict,dictVo);
                   dictVoList.add(dictVo);
               }
   
               EasyExcel.write(response.getOutputStream(), DictEeVo.class).sheet("数据字典").doWrite(dictVoList);
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   

五. 字典导入功能

1. 创建监听器

   @Component
   public class DictListener extends AnalysisEventListener<DictEeVo> {
   
       @Autowired
       private DictMapper dictMapper;
   
       //一行一行读取
       @Override
       public void invoke(DictEeVo dictEeVo, AnalysisContext analysisContext) {
           //调用方法添加数据库
           Dict dict = new Dict();
           BeanUtils.copyProperties(dictEeVo,dict);
   
           QueryWrapper<Dict> queryWrapper = new QueryWrapper<Dict>();
           queryWrapper.eq("id", dict.getId());
           Integer count = dictMapper.selectCount(queryWrapper);
   
           if(count>0){
               dictMapper.updateById(dict);
           }else{
               dictMapper.insert(dict);
           }
       }
       @Override
       public void doAfterAllAnalysed(AnalysisContext analysisContext) {
   
       }
   }
   
   

2. controller

   public R importData(MultipartFile file) {
       dictService.importDictData(file);
       return R.ok();
   }
   
   

3. service

   @Autowired
   private DictListener dictListener;
   
   @Override
   public void importDictData(MultipartFile file) {
       try {
           EasyExcel.read(file.getInputStream(),DictEeVo.class,dictListener).sheet().doRead();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }