引入
为什么使用EasyExcel?
Java解析、生成Excel比较有名的框架有Apache poi、jxl。但他们都存在一个严重的问题就是非常的耗内存，poi有一套SAX模式的API可以一定程度的解决一些内存溢出的问题，但POI还是有一些缺陷，比如07版Excel解压缩以及解压后存储都是在内存中完成的，内存消耗依然很大。
EasyExcel重写了poi对07版Excel的解析，一个3M的excel用POI sax解析依然需要100M左右内存，改用EasyExcel可以降低到几M，并且再大的excel也不会出现内存溢出；03版依赖POI的sax模式，在上层做了模型转换的封装，让使用者更加简单方便。
官网GitHub地址：
https://github.com/alibaba/easyexcel
官方文档地址：
https://www.yuque.com/easyexcel/doc/easyexcel
实例
创建初始数据
SET NAMES utf8mb4; SET FOREIGN_KEY_CHECKS = 0; -- ---------------------------- -- Table structure for user -- ---------------------------- DROP TABLE IF EXISTS `user`; CREATE TABLE `user` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `user_id` bigint(20) NULL DEFAULT NULL, `username` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL, `phone` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL, `create_time` date NULL DEFAULT NULL, PRIMARY KEY (`id`) USING BTREE ) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic; -- ---------------------------- -- Records of user -- ---------------------------- INSERT INTO `user` VALUES (1, 1, 'banq', '13588888888', '2021-11-19'); SET FOREIGN_KEY_CHECKS = 1;
创建SpringBoot项目
导入EasyExcel依赖
<dependency> <groupId>com.alibaba</groupId> <artifactId>easyexcel</artifactId> <version>2.2.10</version> </dependency>
User
@Data public class User { @ExcelIgnore //生成报表时忽略 private Long id; @ExcelProperty(value = "用户ID",index = 0) // 定义表头名称和位置,0代表第一列 private Long userId; @ExcelProperty(value = "用户名称",index = 1) private String username; @ExcelProperty(value = "电话号码",index = 2) private String phone; @ExcelProperty(value = "创建日期",index = 3) @DateTimeFormat("yyyy年MM月dd日") private Date createTime; }
监听器
@Slf4j public class UserDataListener extends AnalysisEventListener<User> { private UserService userService; public UserDataListener(UserService userService) { this.userService = userService; } /** * 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; List<User> list = new ArrayList<User>(); @Override public void invoke(User data, AnalysisContext context) { log.info("解析到一条数据:{}", JSON.toJSONString(data)); list.add(data); if (list.size() >= BATCH_COUNT) { saveData(); list.clear(); } } @Override public void doAfterAllAnalysed(AnalysisContext context) { saveData(); log.info("所有数据解析完成！"); } /** * 加上存储数据库 */ private void saveData() { log.info("{}条数据，开始存储数据库！", list.size()); if (!CollectionUtils.isEmpty(list)) { userService.saveBatch(list); } log.info("存储数据库成功！"); } }
Dao层
@Mapper @Repository public interface UserMapper { void batchInsert(List<User> list); List<User> queryAll(); }
<insert id="batchInsert"> insert into user (user_id,username,phone,create_time) values <foreach collection="list" item="user" separator=","> (#{user.userId},#{user.username},#{user.phone},#{user.createTime}) </foreach> </insert> <select id="queryAll" resultType="ink.banq.demo.entity.User"> select id,user_id,username,phone,create_time from user </select>
Service层
public interface UserService { void saveBatch(List<User> list); List<User> selectAll(); } @Service public class UserServiceImpl implements UserService { @Autowired private UserMapper userMapper; @Override public void saveBatch(List<User> list) { userMapper.batchInsert(list); } @Override public List<User> selectAll() { return userMapper.queryAll(); } }
Controller层
@RestController public class OperateExcelController { @Autowired private UserService userService; /** * 上传文件 * @param file * @return * @throws IOException */ @PostMapping("upload") @ResponseBody public String upload(MultipartFile file) throws IOException { EasyExcel.read(file.getInputStream(), User.class, new UserDataListener(userService)).sheet().doRead(); return "success"; } /** * 导出文件 * @param response * @throws IOException */ @GetMapping("download") public void download(HttpServletResponse response) throws IOException { // 设置上下文类型 response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"); // 设置编码 response.setCharacterEncoding("utf-8"); // 防止中文乱码 String fileName = URLEncoder.encode("文件名称", "UTF-8").replaceAll("\\+", "%20"); response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx"); EasyExcel.write(response.getOutputStream()).sheet("模板").doWrite(userService.selectAll()); } }
启动类
@MapperScan("ink.banq.demo.mapper") @SpringBootApplication public class ExcelApplication { public static void main(String[] args) { SpringApplication.run(ExcelApplication.class,args); } }
测试
（1）测试导入功能，使用Postman测试，如下图所示：
编辑
（2）测试导出功能，浏览器访问：http://localhost:8080/download
编辑
最后附上完整代码：SpringBoot整合EasyExcel进行报表导入导出实例Demo
