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12 KiB
12 KiB
EasyExcel学习
1.环境搭建
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>easyexcel</artifactId>
<version>3.1.2</version>
</dependency>
项目结构：
2.本地模拟实现
1.简单写入excel
第一步：首先创建实体类Employee
@ExcelProperty(value = "员工id",index = 0)注解就是代表的excel表的表头的每一列的名字
@Data@Data
@NoArgsConstructor
@AllArgsConstructor
public class Employee {
@ExcelProperty(value = "员工id",index = 0)
private Integer id;
@ExcelProperty(value = "员工姓名",index = 1)
private String name;
@ExcelProperty(value = "入职日期",index = 2)
private Date date;
@ExcelProperty(value = "员工工资",index = 3)
private Double salary;
}
第二步：创建工具类：用于获取当前文件夹的路径
public class TestFileUtil {
public static String getPath(){
return TestFileUtil.class.getResource("/").getPath().replace("classes/", "");
}
public static void main(String[] args) {
System.out.println(getPath());
}
}
第三步：写操作主要代码：
public class SimpleWrite {
//准备测试数据的方法
private List<Employee> data(int count) {
List<Employee> list = ListUtils.newArrayList();
for (int i = 1; i < count; i++) {
list.add(new Employee(i,"测试数据1"+i,new Date(),6.6*i));
}
return list;
}
//快速入门写数据
@Test
public void write(){
String fileName = TestFileUtil.getPath() + "simpleWrite" + System.currentTimeMillis() + ".xlsx";
// 这里 需要指定写用哪个class去写，然后写到第一个sheet，名字为模板 然后文件流会自动关闭
EasyExcel.write(fileName, Employee.class).sheet("模板").doWrite(data(10));
}
}
2.简单读出excel
只需要一个方法，就可以读出excel表格信息并在控制台打印
//快速入门读数据
public class SimpleReader {
@Test
public void read(){
String fileName = TestFileUtil.getPath() + "simpleWrite1762401148464.xlsx";
// 这里默认每次会读取100条数据 然后返回过来 直接调用使用数据就行
// 具体需要返回多少行可以在`PageReadListener`的构造函数设置
EasyExcel.read(fileName, Employee.class, new PageReadListener<Employee>(dataList -> {
for (Employee demoData : dataList) {
System.out.println(demoData);
}
})).sheet().doRead();
}
}
3.批量写入excel
public class ManyWrite {
//准备测试数据的方法
private List<Employee> data(int count) {
List<Employee> list = ListUtils.newArrayList();
for (int i = 1; i < count; i++) {
list.add(new Employee(i,"测试数据1"+i,new Date(),6.6*i));
}
return list;
}
//批量写数据
@Test
public void write(){
// 方法2: 如果写到不同的sheet 同一个对象
String fileName = TestFileUtil.getPath() + "repeatedWrite" + System.currentTimeMillis() + ".xlsx";
// 这里 指定文件
try (ExcelWriter excelWriter = EasyExcel.write(fileName, Employee.class).build()) {
WriteSheet writeSheet = EasyExcel.writerSheet( "测试数据").build();
long t1 =System.currentTimeMillis();
// 去调用写入
for (int i = 0; i < 100; i++) {
// 分页去数据库查询数据 这里可以去数据库查询每一页的数据
List<Employee> data = data(10000);
excelWriter.write(data, writeSheet);
}
long t2 =System.currentTimeMillis();
System.out.println("耗时："+(t2-t1));
}
}
}
4.读海量数据
读海量数据需要自定义监听器EmployeeListener
//自定义监听器读数据
public class EmployeeListener implements ReadListener<Employee> {
private ArrayList<Employee> list = new ArrayList<>();
private int count = 100;
private EmployeeDao dao;
public EmployeeListener(EmployeeDao dao) {
this.dao = dao;
}
//每读完一行数据，就会调用此方法
@Override
public void invoke(Employee employee, AnalysisContext analysisContext) {
//将读取的一行数据保存到list中
list.add(employee);
//判断是不是到达缓存量了
if(list.size()>=100){
//操作数据库
dao.save(list);
list = new ArrayList<>(count);
}
}
//读完整个excel之后后调用此方法
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
if(list.size()>0){
//操作数据库
dao.save(list);
list = new ArrayList<>(count);
}
}
}
以下是Dao层模拟数据库操作
//模拟操作数据库
public class EmployeeDao {
public void save(List<Employee> list){
System.out.println(list.size()+"模拟操作数据库");
}
}
//读海量数据
public class ManyRead {
@Test
public void read(){
String fileName = TestFileUtil.getPath() + "repeatedWrite1762406295595.xlsx";
ExcelReader reader = EasyExcel.read(fileName, Employee.class, new EmployeeListener(new EmployeeDao())).build();
ReadSheet sheet = EasyExcel.readSheet().build();
reader.read(sheet);
}
}
5.使用模板填充Excel表格
首先在模板中用{.}定义好每一列的名称对应什么
//练习填充数据
public class FillWriter {
//准备测试数据的方法
private List<Employee> data(int count) {
List<Employee> list = ListUtils.newArrayList();
for (int i = 1; i < count; i++) {
list.add(new Employee(i,"测试数据1"+i,new Date(),6.6*i));
}
return list;
}
@Test
public void write(){
String fileName = TestFileUtil.getPath() + "listFill" + System.currentTimeMillis() + ".xlsx";
String templateFileName = TestFileUtil.getPath() + "模板.xlsx";
try (ExcelWriter excelWriter = EasyExcel.write(fileName).withTemplate(templateFileName).build()) {
WriteSheet writeSheet = EasyExcel.writerSheet().build();
long t1 = System.currentTimeMillis();
for (int i = 0; i < 100; i++) {
excelWriter.fill(data(10000), writeSheet);
}
long t2 = System.currentTimeMillis();
System.out.println("耗时："+(t2-t1));
}
}
}
3.前后端端实现导入导出Excel
listener定义:
package com.itheima.listener;
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.read.listener.ReadListener;
import com.itheima.domain.Employee;
import com.itheima.service.EmployeeService;
import java.util.ArrayList;
import java.util.List;
public class EmployeeListener implements ReadListener<Employee> {
/**
* 批量处理的数据量阈值
*/
private int count = 10000;
private EmployeeService dao ;
/**
* 临时存储读取的数据列表
*/
private List<Employee> list = new ArrayList<>(count);
public EmployeeListener(EmployeeService dao) {
this.dao = dao;
}
/**
* 处理每一行数据
* 当读取到一行数据时会调用此方法
* @param employee 当前行的员工数据
* @param analysisContext 分析上下文
*/
@Override
public void invoke(Employee employee, AnalysisContext analysisContext) {
list.add(employee);
// 当累积的数据量达到阈值时，执行批量插入操作
if(list.size()>=count){
dao.addData(list);
// 重新初始化列表，准备下一批数据
list = new ArrayList<>(count);
}
}
/**
* 所有数据解析完成后的回调方法
* 用于处理剩余未达到批量阈值的数据
* @param analysisContext 分析上下文
*/
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
// 处理最后一批未达到阈值的数据
if(list.size()>0){
dao.addData(list);
}
}
}
pojo层：
pojo层和上面定义一致：
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Employee {
@ExcelProperty(value = "员工id",index = 0)
private Integer id;
@ExcelProperty(value = "员工姓名",index = 1)
private String name;
@ExcelProperty(value = "入职日期",index = 2)
private Date date;
@ExcelProperty(value = "员工工资",index = 3)
private Double salary;
}
controller层：
主要是两个方法，一个上传，一个下载
@Controller
@RequestMapping("/")
public class MyController {
@Autowired
private EmployeeService service;
@RequestMapping("/upload")
@ResponseBody
public void upload(MultipartFile file, HttpServletResponse response) throws IOException {
long start = System.currentTimeMillis();
EasyExcel.read(file.getInputStream(), Employee.class, new EmployeeListener(service)).sheet().doRead();
long end = System.currentTimeMillis();
response.setContentType("text/html;charset=utf-8");
response.getWriter().print("上传成功,共用时："+(end-start));
}
@RequestMapping("/download")
public void download(HttpServletResponse response) throws IOException {
// 这里注意 使用swagger 会导致各种问题，直接用浏览器或者用postman
response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
response.setCharacterEncoding("utf-8");
// 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
String fileName = URLEncoder.encode("数据库中导出的数据", "UTF-8").replaceAll("\\+", "%20");
response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
ExcelWriter writer = EasyExcel.write(response.getOutputStream(), Employee.class).build();
WriteSheet sheet = EasyExcel.writerSheet("数据").build();
writer.write(service.getData(), sheet);
writer.close();
}
}
Service层
package com.itheima.service;
import com.itheima.domain.Employee;
import org.springframework.stereotype.Service;
import java.util.List;
public interface EmployeeService {
public List<Employee> getData();
public void addData(List<Employee> list);
}
package com.itheima.service.impl;
import com.itheima.domain.Employee;
import com.itheima.mapper.EmployeeMapper;
import com.itheima.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class EmployeeServiceImpl implements EmployeeService {
@Autowired
private EmployeeMapper dao;
@Override
public List<Employee> getData() {
return dao.getData();
}
@Override
public void addData(List<Employee> list) {
dao.beathInsert(list);
}
}
Mapper层
public interface EmployeeMapper {
public void beathInsert(@Param("list") List<Employee> list);
// @Select("select * from employee ")
@Select("select * from employee")
@ResultType(Employee.class)
List<Employee> getData();
}