Import and export using Spring Boot and EasyExcel

In today's information society, the import and export of data has become increasingly important in various business scenarios. In order to meet complex import and export requirements, we can easily build a powerful and flexible data processing system by combining the Java programming language, Spring Boot framework and EasyExcel library. This article will guide you through a case to learn how to use these tools to implement a complex import and export function.

When it comes to using EasyExcel in Spring Boot to implement complex import and export cases, we can combine the features of Spring Boot to achieve a more flexible and integrated solution. 

EasyExcel is a Java-based open source library specifically designed to handle the import and export operations of Excel files. It provides a simple and easy-to-use API, allowing developers to easily read and write Excel data, while also supporting the processing of large amounts of data, with high performance and flexibility.

EasyExcel's key features and benefits include:

1. Simple and easy to use: EasyExcel provides a simple API interface, allowing developers to get started quickly. Both beginners and experienced developers can easily implement the import and export functions of Excel files.

2. Supports multiple data formats: EasyExcel supports importing and exporting multiple data formats, including basic text, numbers, dates, etc., as well as complex data types such as objects, collections, and nested structures.

3. High performance: EasyExcel performs well when processing large amounts of data. It adopts a stream-based approach, which effectively reduces memory consumption and improves performance and efficiency.

4. Customized styles: Developers can flexibly customize cell styles, including fonts, colors, alignment, etc., to make exported Excel data more beautiful and readable.

5. Data conversion: EasyExcel supports custom data converters that can convert raw data into target formats to meet business needs.

6. Exception handling: EasyExcel provides a rich exception handling mechanism, which can capture and handle exceptions during the import and export process to ensure the integrity and consistency of data.

7. Multi-platform support: EasyExcel can be used in various Java development environments, including traditional Java applications, Web applications, and even mobile application development.

8. Open source community: EasyExcel is an open source project with active community support, where developers can get help, contribute code, and share experiences.

EasyExcel can play a role in many fields such as data migration, report generation, and data analysis, and is especially suitable for scenarios that require frequent processing of Excel data. Whether you are an individual developer or an enterprise development team, you can use EasyExcel to more easily implement data import and export functions, improving development efficiency and user experience.

The following is an import and export case that involves using EasyExcel in Spring Boot to handle the import and export of student information, including custom styles and data conversion.

Assuming that you have configured EasyExcel dependencies in the Spring Boot project, next we will implement the following functions:

1. Import student information from Excel files into the database.
2. Export student information in the database to Excel files, including custom styles and data conversion.

First, make sure you have pom.xmladded the EasyExcel dependency to the file:

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>2.4.3</version>
</dependency>

We can then create the corresponding classes and configurations to implement the above functionality:

1. Create an Studententity class to represent student information:

   import com.alibaba.excel.annotation.ExcelProperty;
   import lombok.Data;
   
   @Data
   public class Student {
       @ExcelProperty("姓名")
       private String name;
   
       @ExcelProperty("年龄")
       private Integer age;
   
       @ExcelProperty("成绩")
       private Double score;
   }
   

   Create a StudentServiceclass to handle the import and export of student information:

   import com.alibaba.excel.EasyExcel;
   import org.springframework.stereotype.Service;
   
   import java.util.List;
   
   @Service
   public class StudentService {
   
       public void importStudents(List<Student> students) {
           // 将导入的学生信息保存到数据库
           // ...
       }
   
       public List<Student> getAllStudents() {
           // 从数据库获取学生信息
           // ...
       }
   
       public void exportStudentsToExcel(String filePath) {
           List<Student> students = getAllStudents();
           EasyExcel.write(filePath, Student.class)
                   .registerWriteHandler(new CustomCellStyleStrategy()) // 注册自定义样式
                   .sheet("Sheet1")
                   .doWrite(students);
       }
   }
   

   Create a CustomCellStyleStrategyclass to customize the style processor:

   import com.alibaba.excel.write.handler.AbstractCellStyleStrategy;
   import org.apache.poi.ss.usermodel.Cell;
   import org.apache.poi.ss.usermodel.IndexedColors;
   import org.apache.poi.ss.usermodel.Row;
   import org.apache.poi.ss.usermodel.Sheet;
   
   public class CustomCellStyleStrategy extends AbstractCellStyleStrategy {
   
       @Override
       protected void setContentCellStyle(Cell cell, Head head, Integer relativeRowIndex) {
           if (relativeRowIndex % 2 == 0) {
               setStyle(cell, IndexedColors.LIGHT_YELLOW.getIndex());
           } else {
               setStyle(cell, IndexedColors.LIGHT_GREEN.getIndex());
           }
       }
   }
   

   Create a StudentControllerclass to handle import and export HTTP requests:

   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.*;
   import org.springframework.web.multipart.MultipartFile;
   
   import java.io.IOException;
   import java.util.List;
   
   @RestController
   @RequestMapping("/students")
   public class StudentController {
   
       @Autowired
       private StudentService studentService;
   
       @PostMapping("/import")
       public void importStudents(@RequestParam("file") MultipartFile file) throws IOException {
           List<Student> students = EasyExcel.read(file.getInputStream()).head(Student.class).sheet().doReadSync();
           studentService.importStudents(students);
       }
   
       @GetMapping("/export")
       public void exportStudents(@RequestParam("file") String filePath) {
           studentService.exportStudentsToExcel(filePath);
       }
   }
   

   In this example, we use Spring Boot to build a basic RESTful API for importing and exporting student information. StudentControllerThe method in importStudentsprocesses the uploaded Excel file and imports student information into the database, and exportStudentsthe method exports student information to an Excel file. At the same time, we StudentServiceregistered a custom style processor in CustomCellStyleStrategy.

   Please make appropriate adjustments and expansions according to your actual needs. This example demonstrates how to integrate EasyExcel in Spring Boot and implement complex import and export functions.

Summary: Through the cases in this article, we have deeply discussed how to use the EasyExcel library to implement complex data import and export functions in Spring Boot projects. We first understood the basic concepts and usage of EasyExcel, and then combined with the Spring Boot framework to build a complete application that includes the import and export of student information. In this case, we learned how to define a data model, write a custom data converter, and implement a custom style processor. Through the convenience of Spring Boot and the powerful functions of EasyExcel, we have successfully implemented a data import and export system that can handle large amounts of data and support custom styles.