下载excel

1.引入依赖

 <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>5.2.5</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>5.2.5</version>
        </dependency>
        <!--&lt;!&ndash; Poi-tl Word 模板引擎&ndash;&gt;-->
        <dependency>
            <groupId>com.deepoove</groupId>
            <artifactId>poi-tl</artifactId>
            <version>1.12.2</version>
        </dependency>

2.示例代码

public download(String id, HttpServletResponse response){

    File file = null;
try{
 Item item = itemService.fetchById(id);
InputStream in = new ClassPathResource("/template/item.xlsx").getInputStream();
File temp = File.createTempFile("temp","xlsx");
OutputStream out = new FileOutputStream(temp);
IOUtils.copy(in,out);//apache poi
out.flush();
out.close();
in.close();

//基于临时文件通过输入流生成xlsx对象并写入数据
XSSFWorkbook workbook = new XSSFWorkbook(temp);
Sheet sheet = workbook.getSheetAt(0);
Row row = sheet.createRow(2);
row.createCell(0).setCellValue(item.getStudentId());
row.createCell(1).setCellValue(item.getName());
row.createCell(2).setCellValue(item.getSex());

//输出流生成导出的文件
String fileName = String.format("学生信息下载%s.xlsx",DateUtil.format(DateUtil.date(),"yyyyMMddHHmmss"));
//DateUtil 引用的是hutool
file = new File(fileName);
FileOutputStream fileOutputStream = new FileOutputStream(file);
workbook.write(fileOutputStream);
fileOutputStream.flush():
fileOutputStream.close();
workbook.close();
//把文件写到response的输出流中 最后再删除两个中间文件
response.reset();
response.setContentType("application/vnd.ms-excel; charset=utf-8");
// 解决下载的excel报错问题
response.setHeader("Access-Control-Allow-Origin","*");
response.setHeader("Content-Length", String.valueOf(file.length()));
response.setHeader("Content-Disposition",String.format("attachment; filename=%s",URLEncoder.encode(fileName, StandardCharsets.UTF_8.displayName())));

exportFile(response, new FileInputStream(file));


}catch(Exception e){

    throw new RuntimeException(e.getMessage());
}finally {
    if(null != file) file.delete();


}

return "ok";


}

public static void exportFile(HttpServletResponse response, InputStream is){

    byte[] buff = new byte[1024];
    BufferedInputStream bis = null;
    OutputStream os = null;
try{
os = response.getOutputStream();
bis = new BufferedInputStream(is);
int i = bis.read(buff);
while(i!=-1){
    os.write(buff, 0, buff.length);
    os.flush();
    i = bis.read(buff);


}


}catch (IOException e){

    e.printStackTrace();
}finally {

    if(null != bis){
    try{
        bis.close();

}catch (IOException e){
    e.printStackTrace();
}

}

if( os != null){

    try{
        os.close();

}catch (IOException e ){
  e.printStackTrace();
}

}

}


}

前端接收时，需要用blob进行接收

即将response.type = "blob"

示例代码

download().done(res=>{
    const url = URL.createObjcetURL(res);//创建一个指向Blob的URL
    const a = document.createElement("a");//创建一个a标签用于下载
    a.href = url;
let fileName = `学生信息${new Date().format("yyyyMMddhhmmssSSS")}.xlsx`;
a.download = fileName; // 设置下载文件名
document.body.appendChild(a);//将a标签添加到文档中以触发下载
a.click();//模拟点击下载文件
document.body.removeChild(a);//移除a标签
    



})