Java之EasyExcel入门Demo

素颜马尾好姑娘i 2023-06-30 05:28 3阅读 0赞

# [Check it out on github][] #

# demo-easy-excel #

## DESC: ##

*  spring integration easy excel

## 快速上手: ##

#### pom.xml ####

<dependencies>
        
        
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>2.1.4</version>
        </dependency>
    </dependencies>

#### 编写Dto ####

@Data
    public class DemoParentDto { 
    
        @ExcelProperty(index = 0,value = { "序号"})
        private Integer num;
    
    }

@EqualsAndHashCode(callSuper = true)
    @AllArgsConstructor
    @NoArgsConstructor
    @Data
    public class DemoUserDto extends DemoParentDto{ 
    
        @ExcelProperty(value = { "姓名"})
        private String name;
    
        @ExcelProperty(value = { "性别"})
        private String sex;
    
        /** * @see LocalDateStringConverter */
        @ExcelProperty(value = "生日",converter = LocalDateStringConverter.class)
        @DateTimeFormat("yyyy-MM-dd")
        private LocalDate birthday;
    
        @ExcelProperty(value = { "年龄"})
        private Integer age;
    
    
        /** * 获取6个测试数据 * @return 6个 */
        public static List<DemoUserDto> getUserDtoTest6(Object search){ 
            List<DemoUserDto> list = new ArrayList<>();
            list.add(new DemoUserDto("quaint","男",LocalDate.of(2011,11,11),9));
            list.add(new DemoUserDto("quaint2","女",LocalDate.of(2001,11,1),19));
            list.add(new DemoUserDto("quaint3","男",LocalDate.of(2010,2,7),10));
            list.add(new DemoUserDto("quaint4","男",LocalDate.of(2011,1,11),9));
            list.add(new DemoUserDto("quaint5","女",LocalDate.of(2021,5,12),-1));
            list.add(new DemoUserDto("quaint6","男",LocalDate.of(2010,7,11),10));
            return list;
        }
    
    }

#### 编写工具类 ####

/** * EasyExcelUtils * @author quaint * @date 2020-01-14 14:26 */
    public abstract class EasyExcelUtils { 
    
        /** * 读取web excel demo , 本地请参考项目内代码 * @param file web 文件 * @param clazz 指定转化类 * @param <T> 类的泛型 * @return web导入的数据 */
        public static <T> List<T> readWebExcel(MultipartFile file, Class<T> clazz){ 
    
            DemoUserListener demoUserListener = new DemoUserListener();
            try { 
                EasyExcel.read(file.getInputStream(), clazz, demoUserListener).sheet().doRead();
                return (List<T>) demoUserListener.getVirtualDataBase();
            } catch (IOException e) { 
                e.printStackTrace();
                return null;
            }
        }
    
        /** * 导出excel web下载, 非web请参考项目内代码 * @param response http下载 * @param dataList 导出的数据 * @param clazz 导出的模板类 * @param fileName 导出的文件名 * @param excludeFiledNames 要排除的filed * @param <T> 模板 */
        public static <T> void exportWebExcel(HttpServletResponse response, List<T> dataList, Class<T> clazz,
                                     String fileName, Set<String> excludeFiledNames) { 
    
            // 这里注意 有同学反应使用swagger 会导致各种问题，请直接用浏览器或者用postman
            response.setContentType("application/vnd.ms-excel");
            response.setCharacterEncoding("utf-8");
            response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xlsx");
    
            try { 
                // 导出excel
                EasyExcel.write(response.getOutputStream(), clazz)
                        .excludeColumnFiledNames(excludeFiledNames)
                        .sheet("fileName")
                        .doWrite(dataList);
            } catch (IOException e) { 
                System.err.println("创建文件异常!");
            }
    
        }
    
    }

#### 编写监听器(导入使用) ####

@EqualsAndHashCode(callSuper = true)
    @Slf4j
    @Data
    public class DemoUserListener extends AnalysisEventListener<DemoUserDto> { 
    
        /** * 每隔5条存储数据库，实际使用中可以3000条，然后清理list ，方便内存回收 */
        private static final int BATCH_COUNT = 5;
    
        private List<DemoUserDto> list = new ArrayList<>();
    
        /** * 虚拟数据库 */
        private List<DemoUserDto> virtualDataBase = new ArrayList<>();
    
    
        /** * 这个每一条数据解析都会来调用 * * @param data * one row value. Is is same as {@link AnalysisContext#readRowHolder()} * @param context */
        @Override
        public void invoke(DemoUserDto data, AnalysisContext context) { 
            log.info("解析到一条数据:{}", JSONObject.toJSONString(data));
            list.add(data);
            // 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
            if (list.size() >= BATCH_COUNT) { 
                saveData();
                // 存储完成清理 list
                list.clear();
            }
        }
    
        /** * 所有数据解析完成了 都会来调用 * * @param context */
        @Override
        public void doAfterAllAnalysed(AnalysisContext context) { 
            // 这里也要保存数据，确保最后遗留的数据也存储到数据库
            saveData();
            log.info("所有数据解析完成！");
        }
    
        /** * 在转换异常 获取其他异常下会调用本接口。抛出异常则停止读取。如果这里不抛出异常则 继续读取下一行。 * @param exception exception * @param context context * @throws Exception e */
        @Override
        public void onException(Exception exception, AnalysisContext context) { 
            log.error("解析失败，但是继续解析下一行:{}", exception.getMessage());
            // 如果是某一个单元格的转换异常 能获取到具体行号
            // 如果要获取头的信息 配合invokeHeadMap使用
            if (exception instanceof ExcelDataConvertException) { 
                ExcelDataConvertException excelDataConvertException = (ExcelDataConvertException)exception;
                log.error("第{}行，第{}列解析异常", excelDataConvertException.getRowIndex(),
                        excelDataConvertException.getColumnIndex());
            }
        }
    
        /** * 加上存储数据库 */
        private void saveData() { 
            log.info("{}条数据，开始存储数据库！", list.size());
            virtualDataBase.addAll(list);
            log.info("存储数据库成功！");
        }
    }

#### 编写自定义转换器(LocalDate 导入导出 转换) ####

public class LocalDateTimeConverter implements Converter<LocalDateTime> { 
    
        @Override
        public Class supportJavaTypeKey() { 
            return LocalDateTime.class;
        }
    
        @Override
        public CellDataTypeEnum supportExcelTypeKey() { 
            return CellDataTypeEnum.STRING;
        }
    
        @Override
        public LocalDateTime convertToJavaData(CellData cellData, ExcelContentProperty contentProperty,
                                               GlobalConfiguration globalConfiguration){ 
            // 将excel 中的 数据 转换为 LocalDateTime
            if (contentProperty == null || contentProperty.getDateTimeFormatProperty() == null) { 
                return LocalDateTime.parse(cellData.getStringValue(), DateTimeFormatter.ISO_LOCAL_DATE_TIME);
            } else { 
                // 获取注解的 format 注意,注解需要导入这个 excel.annotation.format.DateTimeFormat;
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern(contentProperty.getDateTimeFormatProperty().getFormat());
                return LocalDateTime.parse(cellData.getStringValue(), formatter);
            }
        }
    
        @Override
        public CellData convertToExcelData(LocalDateTime value, ExcelContentProperty contentProperty,
                                           GlobalConfiguration globalConfiguration) { 
            // 将 LocalDateTime 转换为 String
            if (contentProperty == null || contentProperty.getDateTimeFormatProperty() == null) { 
                return new CellData(value.toString());
            } else { 
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern(contentProperty.getDateTimeFormatProperty().getFormat());
                return new CellData(value.format(formatter));
            }
        }
    }

#### 编写spi测试 ####

@Controller
    public class DemoEasyExcelSpi { 
        
        @PostMapping("/in/excel")
        public String inExcel(@RequestParam("inExcel") MultipartFile inExcel, Model model){ 
    
            if (inExcel.isEmpty()){ 
                // 读取 local 指定文件
                List<DemoUserDto> demoUserList = EasyExcelUtils.readLocalExcel("ExcelTest", DemoUserDto.class);
                model.addAttribute("users", demoUserList);
            } else { 
                // 读取 web 上传的文件
                List<DemoUserDto> demoUserList = EasyExcelUtils.readWebExcel(inExcel, DemoUserDto.class);
                model.addAttribute("users", demoUserList);
            }
            return "index";
        }
    
        @PostMapping("/out/excel")
        public void export(HttpServletResponse response){ 
    
            String search = "@RequestBody Object search";
            // 根据前端传入的查询条件 去库里查到要导出的dto
            List<DemoUserDto> userDto = DemoUserDto.getUserDtoTest6(search);
            // 要忽略的 字段
            List<String> ignoreIndices = Collections.singletonList("性别");
    
            // 根据类型获取要反射的对象
            Class clazz = DemoUserDto.class;
    
            // 遍历所有字段, 找到忽略的字段
            Set<String> excludeFiledNames = new HashSet<>();
            while (clazz != Object.class){ 
                Arrays.stream(clazz.getDeclaredFields()).forEach(field -> { 
                    ExcelProperty ann = field.getAnnotation(ExcelProperty.class);
                    if (ann!=null && ignoreIndices.contains(ann.value()[0])){ 
                        // 忽略 该字段
                        excludeFiledNames.add(field.getName());
                    }
                });
                clazz = clazz.getSuperclass();
            }
    
            // 设置序号
            AtomicInteger i = new AtomicInteger(1);
            userDto.forEach(u-> u.setNum(i.getAndIncrement()));
    
            // 创建本地文件
            EasyExcelUtils.exportLocalExcel(userDto,DemoUserDto.class,"ExcelTest",excludeFiledNames);
            // 创建web文件
            EasyExcelUtils.exportWebExcel(response,userDto,DemoUserDto.class,"ExcelTest",null);
    
        }
    }

# [Check it out on github][] #

[Check it out on github]: https://github.com/quaintclever/Java-SID/tree/master/demo-easy-excel