EasyExcel的简单易上手使用

1.EasyExcel 导出功能的实现

首先需要引入EasyExcel相关的依赖包

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>2.2.6</version>
</dependency>

导出的工具类以及代码如下：

package com.wei.weistudy.utils;

import com.alibaba.excel.EasyExcel;
import com.alibaba.fastjson.JSON;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class EasyExcelUtils<T> {
    /**
     * 文件下载并且失败的时候返回json（默认失败了会返回一个有部分数据的Excel）
     * @param tableDate 要导出的数据
     * @param classes 数据对应的实体类
     * @param downloadFileName 导出文件的文件名
     * @param response response
     * @since 2.1.1
     */
    public void downloadFailedUsingJson(List<T> tableDate, Class<T> classes, String downloadFileName, HttpServletResponse response) throws IOException {
        // 这里注意 有同学反应使用swagger 会导致各种问题，请直接用浏览器或者用postman
        try {
            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(downloadFileName, "UTF-8").replaceAll("\\+",  "%20");
            response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xls");
            // 这里需要设置不关闭流
            EasyExcel.write(response.getOutputStream(), classes).autoCloseStream(Boolean.FALSE).sheet("模板")
                    .doWrite(tableDate);
        } catch (Exception e) {
            // 重置response
            response.reset();
            response.setContentType("application/json");
            response.setCharacterEncoding("utf-8");
            Map<String, String> map = new HashMap<>(2);
            map.put("status", "failure");
            map.put("message", "下载文件失败" + e.getMessage());
            response.getWriter().println(JSON.toJSONString(map));
            
        }
    }
}

实体类代码：

package com.wei.weistudy.pojo;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.Data;

/**
* 自己用来测试的一个简单的实体类
* @ExcelProperty 注解  value：对应导出的excel表格的列名  index对应该列所在位置
*/
@Data
public class ExportCourse {
    @ExcelProperty(value = "课程号",index = 0)
    private String cid;
    @ExcelProperty(value = "课程名",index = 1)
    private String cname;
    @ExcelProperty(value = "教师号",index = 2)
    private String tid;
}

@Data注解自动生成 getter、setter方法需要引入lombok依赖&下载lombok插件配合使用
<dependency>
     <groupId>org.projectlombok</groupId>
     <artifactId>lombok</artifactId>
     <version>1.16.10</version>
     <scope>provided</scope>
</dependency>

controller层代码：

package com.wei.weistudy.controller;

import com.wei.weistudy.pojo.Course;
import com.wei.weistudy.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.UnsupportedEncodingException;
import java.util.Calendar;
import java.util.List;

@RestController
@RequestMapping(value = "/hello")
public class HelloController {

    @Autowired
    private UserService userService;

	//导出功能
    @RequestMapping(value = "/exportCourse")
    public void exportCourse(HttpServletResponse response) throws Exception{
        userService.exportCourse(response);
    }
	//导入功能
    @RequestMapping(value = "/importCourse")
    public void importCourse(MultipartFile file, Long updateSupport){
        userService.importCourse(file,updateSupport);
    }
}

service层代码：

package com.wei.weistudy.service;

import com.wei.weistudy.pojo.Course;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

public interface UserService {

    void exportCourse(HttpServletResponse response) throws IOException;

    void importCourse(MultipartFile file, Long updateSupport);
}

serviceImpl层代码(这块只写了导出的，导入的后面写)：

package com.wei.weistudy.serviceimpl;

import com.alibaba.excel.EasyExcel;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.wei.weistudy.mapper.UserMapper;
import com.wei.weistudy.pojo.Course;
import com.wei.weistudy.pojo.ExportCourse;
import com.wei.weistudy.service.UserService;
import com.wei.weistudy.utils.EasyExcelUtils;
import com.wei.weistudy.utils.ImportCourse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.concurrent.TimeUnit;

@Service
@Slf4j
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

	@Override
    public List<Course> getInfo() {
        List<Course> courses = userMapper.getInfo();
        return courses;
    }    

    @Override
    public void exportCourse(HttpServletResponse response) throws IOException {

            Calendar calendar = Calendar.getInstance();
            String year = String.valueOf(calendar.get(Calendar.YEAR));
            String month = String.valueOf(calendar.get(Calendar.MONTH));
            String day = String.valueOf(calendar.get(Calendar.DAY_OF_MONTH));
            String title = "学生表" + year + "-" + month + "-" + day;
            String fileName = title;
            //这是一个查询自己要导出的数据的方法 根据自己的需求去查询
            List<Course> info = getInfo();
            List<ExportCourse> list = new ArrayList<>();
            for (Course course : info) {
                ExportCourse exportCourse = new ExportCourse();
                BeanUtils.copyProperties(course, exportCourse);
                list.add(exportCourse);
            }

            EasyExcelUtils<ExportCourse> easyExcelUtils = new EasyExcelUtils();
            easyExcelUtils.downloadFailedUsingJson(list, ExportCourse.class, fileName, response);
    }
}

2.EasyExcel 导入功能的实现

导入功能对应的 controller层、service层、pojo层与导出的一致

导入也有对应的工具类，代码如下：

package com.wei.weistudy.utils;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.wei.weistudy.mapper.UserMapper;
import com.wei.weistudy.pojo.Course;
import com.wei.weistudy.pojo.ExportCourse;
import org.springframework.beans.BeanUtils;

import java.util.ArrayList;
import java.util.List;
// 继承AnalysisEventListener类 泛型对应你要导入的实体类对象
public class ImportCourse extends AnalysisEventListener<ExportCourse> {

    private UserMapper userMapper;

    List<Course> list = new ArrayList<>();

    public ImportCourse(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

    //每读取一行就调用该方法
    @Override
    public void invoke(ExportCourse data, AnalysisContext context) {
        Course course = new Course();
        BeanUtils.copyProperties(data,course);
        list.add(course);
    }
    //全部读取完成就调用该方法
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        userMapper.insertList(list);
    }
}

导入功能对应的serviceImpl代码如下：

package com.wei.weistudy.serviceimpl;

import com.alibaba.excel.EasyExcel;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.wei.weistudy.mapper.UserMapper;
import com.wei.weistudy.pojo.Course;
import com.wei.weistudy.pojo.ExportCourse;
import com.wei.weistudy.service.UserService;
import com.wei.weistudy.utils.EasyExcelUtils;
import com.wei.weistudy.utils.ImportCourse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.concurrent.TimeUnit;

@Service
@Slf4j
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;
    
    @Override
    public void importCourse(MultipartFile file) {
        try {
            BufferedInputStream bufferedInputStream=new BufferedInputStream(file.getInputStream());
            EasyExcel.read(bufferedInputStream, ExportCourse.class,new ImportCourse(userMapper)
                    .sheet()
                    .doRead();;
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}