Preface
During project development, file upload and download functions are sometimes used. The project provides a template for users to download. After the user downloads it, add the required data content and upload it to the project. The project backend receives the file and parses it. If it needs to be saved in the database, it will perform database-related operations.So how to implement the file upload and download function? The following case is for reference (this project is based on springboot, the framework uses the everyone permissions framework, and the front-end and back-end interaction uses ajax communication).
1. Download the template file
1. Create template file download link on the front end
<a href="http://localhost:8080/admin/admin/equipment/download/" style="float: right" @click="tip">模板文件下载</a>
//此方法是点击模板文件下载，弹出注意事项。
<script>
var vm = new Vue({
el:'#rrapp',
data:{
},
methods: {
tip: function(){
layer.open({
type: 0,
offset: 'rt',
title: '注意事项'
,content: '设备名称不得为空；经费来源选填（行政、教学、其它）中的一个，分类号和归属单位查看sheet表2；其余可为空。'
});
}
}
});
</script>
2. Back-end interface writing
Add project dependencies
<!-- POI support -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.9</version>
</dependency>
<!-- support xlsx,docx.. -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.9</version>
</dependency>
<!-- /POI support -->
@RestController
@RequestMapping("admin/equipment")
public class EquipmentController {
/**
* 模板文件下载
* @param response
*/
@SysLog("模板文件下载")
@RequestMapping("/download")
public void download(HttpServletResponse response) {
try {
//获取文件模板
InputStream fis = Thread.currentThread().getContextClassLoader().getResourceAsStream("设备仪器用表.xls");
HSSFWorkbook workbook = new HSSFWorkbook(fis);
//设置文件ContentType类型，这样设置，会自动判断下载文件类型
response.setContentType("application/binary;charset=ISO8859-1");
//转码，免得文件名中文乱码
String fileName = java.net.URLEncoder.encode("设备仪器用表", "UTF-8");
//设置文件下载头
response.setHeader("Content-disposition", "attachment; filename=" + fileName + ".xls");
ServletOutputStream out = null;
out = response.getOutputStream();
workbook.write(out);
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
//关闭文件输出流
}
return;
}
}
3. The location of the file template in the backend interface
Note : The location of this template file is under the resources folder, which is at the same level as templates.
2. Upload files and import data into the database
1. Create a file upload button on the front end
<a class="btn btn-primary" id="upload"><i class="fa fa-plus"></i> 批量导入</a>
<script>
new AjaxUpload('#upload', {
action: baseURL + "admin/equipment/upload",
name: 'file',
autoSubmit:true,
responseType:"json",
// 告诉jQuery不要去处理发送的数据
processData : false,
// 告诉jQuery不要去设置Content-Type请求头
contentType : false,
onSubmit:function(file, extension){
if (!(extension && /^(xlsx|xls)$/.test(extension.toLowerCase()))){
alert('只支持xlsx、xls格式的Excel文件！');
return false;
}
},
onComplete : function(file, r){
if(r.code == 0){
alert(r.url);
vm.reload();
}else{
alert(r.msg);
}
}
});
</script>
2. Entity class
package io.renren.modules.admin.entity;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import io.renren.common.validator.group.AddGroup;
import io.renren.common.validator.group.UpdateGroup;
import lombok.Data;
import javax.validation.constraints.NotBlank;
import java.io.Serializable;
import java.util.Date;
/**
* 设备表
*
* @author yzs
* @email [email protected]
* @date 2020-11-19 15:26:13
*/
@Data
@TableName("equipment")
public class EquipmentEntity implements Serializable {
private static final long serialVersionUID = 1L;
/**
*
*/
@TableId
private Long id;
/**
* 设备编号
*/
private String number;
/**
* 分类号
*/
private String classnum;
/**
* 分类名
*/
@TableField(exist = false)
@NotBlank(message="分类名不能为空", groups = {
AddGroup.class, UpdateGroup.class})
private String classname;
/**
* 设备名称
*/
private String name;
/**
* 型号
*/
private String model;
/**
* 规格
*/
private String specification;
/**
* 单价
*/
private Double price;
/**
* 厂商
*/
private String vendor;
/**
* 出厂号
*/
private String factorynum;
/**
* 购置日期
*/
private Date time;
/**
* 经费来源
*/
private String funding;
/**
* 归属单位编号
*/
private String deptnum;
/**
* 归属单位名称
*/
@TableField(exist = false)
private String deptname;
/**
* 状态（0未分配 1已分配 2已报废）
*/
private Integer status;
}
3. Back-end interface writing
@RestController
@RequestMapping("admin/equipment")
public class EquipmentController {
@Autowired
private EquipmentService equipmentService;
/**
* 上传文件
*/
@SysLog("上传文件")
@RequestMapping("/upload")
public R upload(@RequestParam("file") MultipartFile file) throws Exception {
if (file.isEmpty()) {
throw new RRException("上传文件不能为空");
}
FileInputStream inputStream = (FileInputStream) file.getInputStream();
//用于存储解析后的Excel文件
Workbook workbook = new HSSFWorkbook(inputStream);
//得到表
Sheet sheet = workbook.getSheetAt(0);
//获取标题内容
// Row rowTitle = sheet.getRow(1);
// if (rowTitle != null){
// int cellCount = rowTitle.getPhysicalNumberOfCells();
// for (int cellNum=0; cellNum<cellCount; cellNum++){
// Cell cell = rowTitle.getCell(cellNum);
// if (cell != null){
// int cellType = cell.getCellType();
// String cellValue = cell.getStringCellValue();
// }
// }
// }
//获取内容信息
int rowCount = sheet.getPhysicalNumberOfRows();
for (int rowNum=1; rowNum<rowCount; rowNum++){
Row rowData = sheet.getRow(rowNum);
if (rowData != null) {
EquipmentEntity equipmentEntity = new EquipmentEntity();
//设备编号
String number = String.valueOf(rowData.getCell(0));
if(number == "null"){
number = UUID.randomUUID().toString().substring(0,8);
equipmentEntity.setNumber(number);
}else {
number = number.substring(0,number.indexOf("."));
equipmentEntity.setNumber(number);
}
//设备名称
String name = String.valueOf(rowData.getCell(1));
if (name == "null"){
equipmentEntity.setName(name);
}else {
name = name.substring(0,name.indexOf("."));
equipmentEntity.setName(name);
}
//分类号
String classnum = String.valueOf(rowData.getCell(2));
if (classnum == "null"){
equipmentEntity.setClassnum(classnum);
}else {
classnum = classnum.substring(0,classnum.indexOf("."));
equipmentEntity.setClassnum(classnum);
}
//型号
String model = String.valueOf(rowData.getCell(3));
if(model == "null"){
equipmentEntity.setModel(model);
}else {
model = model.substring(0,model.indexOf("."));
equipmentEntity.setModel(model);
}
//规格
String specification = String.valueOf(rowData.getCell(4));
if (specification == "null"){
equipmentEntity.setSpecification(specification);
}else {
specification = specification.substring(0,specification.indexOf("."));
equipmentEntity.setSpecification(specification);
}
//单价
String jiage = String.valueOf(rowData.getCell(5));
if (jiage != "null") {
Double price = Double.valueOf(String.valueOf(jiage));
equipmentEntity.setPrice(price);
}
//厂商
String vendor = String.valueOf(rowData.getCell(6));
if (vendor == "null"){
equipmentEntity.setVendor(vendor);
}else {
vendor = vendor.substring(0,vendor.indexOf("."));
equipmentEntity.setVendor(vendor);
}
//出厂号
String factorynum = String.valueOf(rowData.getCell(7));
if (factorynum == "null"){
equipmentEntity.setFactorynum(factorynum);
}else {
factorynum = factorynum.substring(0,factorynum.indexOf("."));
equipmentEntity.setFactorynum(factorynum);
}
//购置日期
Date time = rowData.getCell(8).getDateCellValue();
if(time != null) {
equipmentEntity.setTime(time);
}else {
equipmentEntity.setTime(new Date());
}
//经费来源
String funding = String.valueOf(rowData.getCell(9));
equipmentEntity.setFunding(funding);
//归属单位
String deptnum = String.valueOf(rowData.getCell(10));
if (deptnum == "null"){
equipmentEntity.setDeptnum(deptnum);
}else {
deptnum = deptnum.substring(0,deptnum.indexOf("."));
equipmentEntity.setDeptnum(deptnum);
}
//设置设备仪器的默认属性值，状态为未分配
equipmentEntity.setStatus(0);
equipmentService.save(equipmentEntity);
}
}
//关闭流
inputStream.close();
return R.ok().put("url","成功");
}
}
Note : The process of database storage here takes up a lot of memory, and the performance needs to be optimized. The reason is that when reading the content of the uploaded file, the file is read by traversing the lines, and the database access operation is performed every time a line of information is read. There are as many IO operations as there are rows, and the performance is not good.
3. Summary
The above is what I will talk about today. This article only briefly introduces the use of java code to implement file upload and file download. I hope it can help you.