First introduce pom dependencies:
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>easyexcel</artifactId>
<version>3.1.3</version>
</dependency>1. Download
The backend java code is as follows:
@WebServlet("/download")
public class DownloadServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("application/octet-stream;charset=UTF-8");
response.setHeader("Content-disposition", "attachment;filename=down.xlsx");
EasyExcel.write(response.getOutputStream(), DownloadData.class).sheet("模板").doWrite(data());
}
private List<DownloadData> data() {
List<DownloadData> list = new ArrayList<>();
for (int i = 0; i < 7; i++) {
DownloadData data = new DownloadData();
data.setString("字符串" + i);
data.setDate(new Date());
data.setDoubleData(0.56+i);
list.add(data);
}
return list;
}
}
public class DownloadData {
@ExcelProperty("字符串标题")
private String string;
@ExcelProperty("日期标题")
private Date date;
@ExcelProperty("数字标题")
private Double doubleData;
public String getString() {
return string;
}
public void setString(String string) {
this.string = string;
}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
public Double getDoubleData() {
return doubleData;
}
public void setDoubleData(Double doubleData) {
this.doubleData = doubleData;
}
}The Excel file named down.xlsx can be obtained by accessing the web terminal. The content of the file is as follows:
2. Upload
Front-end html code:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
function func() {
}
</script>
</head>
<body>
<h1 onclick="func()">Hello tomcat1!</h1>
<form action="/webtest/upload" method="post" enctype="multipart/form-data">
用户名:<input type="text" name="username" /><br />
上传文件:<input type="file" name="uploadFile" /><br />
<input type="submit" value="上传" />
</form>
</body>
</html>Backend java code:
@MultipartConfig
@WebServlet("/upload")
public class UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Part uploadFile = request.getPart("uploadFile");
InputStream inputStream = uploadFile.getInputStream();
UploadDAO uploadDAO = new UploadDAO();
EasyExcel.read(inputStream, DownloadData.class, new UploadDataListener(uploadDAO)).sheet().doRead();
}
}
/**
* 存储上传的数据的类
*
**/
public class UploadDAO {
public void save(List<DownloadData> list) {
for(int i=0;i<list.size();i++){
System.out.println("正在保存数据："+list.get(i).getString());
}
}
}
/**
* 模板的读取类
*/
public class UploadDataListener implements ReadListener<DownloadData> {
/**
* 每隔5条存储数据库，实际使用中可以100条，然后清理list ，方便内存回收
*/
private static final int BATCH_COUNT = 5;
private List<DownloadData> cachedDataList = new ArrayList<>(BATCH_COUNT);
private UploadDAO uploadDAO;
/**
* DataListener不能被spring管理，每次读取excel都要new,同时使用这个构造方法把spring管理的类传进来
*/
public UploadDataListener(UploadDAO uploadDAO) {
this.uploadDAO = uploadDAO;
}
/**
* 每一条数据解析都会来调用这个方法
*/
@Override
public void invoke(DownloadData data, AnalysisContext context) {
cachedDataList.add(data);
// 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
if (cachedDataList.size() >= BATCH_COUNT) {
saveData();
// 存储完成清理 list
cachedDataList.clear();
}
}
/**
* 所有数据解析完成了 都会来调用
*
* @param context
*/
@Override
public void doAfterAllAnalysed(AnalysisContext context) {
// 这里也要保存数据，确保最后遗留的数据也存储到数据库
saveData();
}
/**
* 加上存储数据库
*/
private void saveData() {
uploadDAO.save(cachedDataList);
}
}The data entity follows the download class DownloadData.java, and the attachment down.xlsx downloaded before uploading on the front-end page
After clicking upload, the background output is as follows:
Successfully read the content of the uploaded file.
3. Download file style
In general, you need to fine-tune the style of the exported Excel:
import java.util.Date;
import org.apache.poi.ss.usermodel.IndexedColors;
import com.alibaba.excel.annotation.ExcelIgnore;
import com.alibaba.excel.annotation.ExcelProperty;
import com.alibaba.excel.annotation.write.style.ColumnWidth;
import com.alibaba.excel.annotation.write.style.ContentFontStyle;
import com.alibaba.excel.annotation.write.style.HeadFontStyle;
import com.alibaba.excel.annotation.write.style.HeadStyle;
import com.alibaba.excel.enums.poi.FillPatternTypeEnum;
//设置头背景颜色 org.apache.poi.ss.usermodel.IndexedColors IndexedColors.CORNFLOWER_BLUE.getIndex()
@HeadStyle(fillForegroundColor = 24)
//头字体设置成20
@HeadFontStyle(fontHeightInPoints = 20)
//内容的背景设置成绿色 IndexedColors.GREEN.getIndex()
//@ContentStyle(fillPatternType = FillPatternTypeEnum.SOLID_FOREGROUND, fillForegroundColor = 17)
//内容字体设置成12
@ContentFontStyle(fontHeightInPoints = 12)
@ColumnWidth(25)
public class DownloadData {
@ExcelProperty("字符串标题")
private String string;
/**
* 忽略这个字段
*/
@ExcelIgnore
@ExcelProperty("日期标题")
private Date date;
/**
* 宽度为50
*/
@ColumnWidth(50)
@ExcelProperty("数字标题")
private Double doubleData;
public String getString() {
return string;
}
public void setString(String string) {
this.string = string;
}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
public Double getDoubleData() {
return doubleData;
}
public void setDoubleData(Double doubleData) {
this.doubleData = doubleData;
}
}Among them, ColumnWidth can set the column width. According to the above, you can adjust the background color and font size of the title, the background color and font size of the content line, etc. The adjusted effect is as follows:
For more style adjustments, please refer to easyexcel: easyexcel —— JAVA Parsing Excel Tool Java parsing and generating Excel The more famous frameworks are Apache poi, jxl - Gitee.com