Dynamically configure entity class annotation parameters when starting a Java project

In Java development, especially when using Easypoi's @Excel annotation to process Excel import and export pictures, it is often necessary to dynamically configure savePath parameters according to different environments (local development, test environment, production environment). This article introduces a method to dynamically modify savePath parameter of Easypoi @Excel annotation when the project starts, and avoid manually modifying the code.

Problem: Limitations of static configuration savePath

Send savePath directly in @Excel annotation, for example: @Excel(savePath = "D:\\upload\\") This static configuration method requires code modification in different environments, and the deployment is cumbersome and error-prone.

Solution: Dynamically get and set savePath

We can dynamically get savePath by reading the system environment variable or configuration file at the project startup, and then setting it into the ImportParams object before Easypoi import and export.

Here is a sample code that demonstrates how to set savePath dynamically:

 import org.apache.poi.ss.usermodel.Workbook;
import org.jeecg.common.util.oConvertUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import cn.afterturn.easypoi.excel.ExcelExportUtil;
import cn.afterturn.easypoi.excel.ExcelImportUtil;
import cn.afterturn.easypoi.excel.entity.ExportParams;
import cn.afterturn.easypoi.excel.entity.ImportParams;
import cn.afterturn.easypoi.excel.entity.params.ExcelExportEntity;
import java.io.File;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;

@Service
public class EasypoiService {

    @Value("${easypoi.savePath}")
    private String savePath;


    public void exportExcel(List> list, Class> pojoClass, String fileName) throws Exception {
        ExportParams exportParams = new ExportParams("Title", "Subtitle");
        Workbook workbook = ExcelExportUtil.exportExcel(exportParams, pojoClass, list);
        File savefile = new File(savePath fileName ".xls");
        FileOutputStream fos = new FileOutputStream(savefile);
        workbook.write(fos);
        fos.close();
    }

    public List> importExcel(Class> pojoClass, String filePath) throws Exception {
        ImportParams importParams = new ImportParams();
        importParams.setSaveUrl(savePath); // Dynamically set savePath
        return ExcelImportUtil.importExcel(new File(filePath), pojoClass, importParams);
    }
}

Code description:

• Use @Value("${easypoi.savePath}") annotation to read the easypoi.savePath property from a configuration file such as application.yml or application.properties and assign it to the savePath variable.
• In exportExcel and importExcel methods, use the savePath variable to set the path parameters of ExportParams and ImportParams objects.

Configuration file example (application.yml):

 easypoi:
  savePath: /opt/upload/ # Linux environment# savePath: D:\\upload\\ # Windows environment

In this way, you can change savePath by simply modifying the configuration file, without recompiling the code, making it easier to deploy in different environments. Remember to adjust the path according to your actual project structure and environment. If you use other configuration methods, such as environment variables, you need to modify the code accordingly to read the value of the environment variable.

This approach is more flexible and easier to maintain than hardcode paths directly in code. It takes advantage of the dependency injection function of the Spring framework, decoupling configuration from the code, improving the maintainability and reusability of the code. At the same time, the potential problems caused by direct use of absolute paths are also avoided.

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