Java 导入导出功能总结
项目中经常需要使用导入导出功能来加快数据的操作，尤其是一些项目的后台管理系统，特此奉上我们项目中使用到导入导出代码，均可以实际使用。准备工作：pom中加入以下依赖:
org.apache.poi
poi
3.15-beta2
org.apache.poi
poi-ooxml
3.15-beta2
导入功能
基本思路：读取到文件--->创建表格并把文件流内容读取到表格中--->解析表格--->持久化
package com.simons.cn.springbootdemo.util;
import com.simons.cn.springbootdemo.bean.Movie;
import com.simons.cn.springbootdemo.service.Weixin.IndexService;
import org.apache.poi.ss.usermodel.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.FileCopyUtils;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.List;
@Service
public class FilePortUtil {
private static final Logger log = LoggerFactory.getLogger(FilePortUtil.class);
@Autowired
private IndexService indexService;
/**
* 导入功能
*
* @param multipartFile
* @return
*/
public int fileImport(MultipartFile multipartFile) {
File file = null;
Workbook workbook = null;
int totalNum = 0;
/*得到的path是 /D:/springbootdemo/target/springbootdemo/WEB-INF/classes/ */
String path = FilePortUtil.class.getClassLoader().getResource("/").getPath();
/*拼接后的path就是 /D:/springbootdemo/target/springbootdemo/WEB-INF/电影正式资源.xlsx /*/
path = path.substring(0, path.indexOf("WEB-INF") + "WEB-INF".length()) + "/" + multipartFile.getOriginalFilename();
file = new File(path);
try {
/*把文件流copy读取到文件中*/
FileCopyUtils.copy(multipartFile.getBytes(), file);
workbook = WorkbookFactory.create(new FileInputStream(file));
List list = new ArrayList<>();
/*遍历sheet页*/
for (int i = 0; i < workbook.getNumberOfSheets(); i++) {
Sheet sheet = workbook.getSheetAt(i);
if (sheet == null) {
continue;
}
/*统计导入的总条数，要是你的excell包含了表头，就不用加1了*/
if (sheet.getLastRowNum() > 0) {
totalNum += sheet.getLastRowNum() + 1;
}
/*遍历行，这里j的初始值取1是因为我的表格里第一行是表头*/
for (int j = 1; j < sheet.getPhysicalNumberOfRows(); j++) {
Row row = sheet.getRow(j);
/*解析列，下标从0开始*/
Cell cell2 = row.getCell(2);
Cell cell3 = row.getCell(3);
if (cell2 == null || cell3 == null) {
continue;
}
String name = this.getCellValue(cell2);
String original = this.getCellValue(cell3);
/*我这里省略了很多数据清洗、校验的代码*/
Movie movie = new Movie();
movie.setName(name);
movie.setOriginal(original);
list.add(movie);
}
/*持久化：批量新增*/
indexService.insertBatch(list);
}
/*解析完删除此路径下的文件*/
file.delete();
return totalNum;
} catch (Exception e) {
e.printStackTrace();
log.error("导入功能公用类异常exception={}", e);
}
return totalNum;
}
public String getCellValue(Cell cell) {
if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) {
return String.valueOf(cell.getBooleanCellValue());
} else if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
Double d = cell.getNumericCellValue();
return String.valueOf(d.intValue());
}
return String.valueOf(cell.getStringCellValue());
}
} 一般来说，每个导入功能处理的逻辑不太一样，里面的校验、数据对象也不太一样，所以我这里就没有封装成公用类而仅仅写成service，里面具体的逻辑交由程序员填充。
导出功能
导出功能是最常用的，下面的代码中用到了反射的思想，比如，你查询出来的List
基本思路：创建表格对象--->将数据set进表格--->将表格流写入response返回
package com.simons.cn.springbootdemo.util;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.lang.time.DateFormatUtils;
import org.apache.poi.hssf.usermodel.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;
import javax.servlet.http.HttpServletResponse;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
public class FilePortUtil {
private static final Logger log = LoggerFactory.getLogger(FilePortUtil.class);
/**
* 导出功能
* 注意：泛型T类字段名和containBean集合里字段名字的一致性
*
* @param response
* @param title 表名
* @param headers 表头
* @param list 数据集
* @param containBean 数据集类型字段
* @param
* @throws Exception
*/
public static void exportExcel(HttpServletResponse response, String title, String[] headers, List list, List containBean) throws Exception {
HSSFWorkbook workbook = null;
try {
workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet(title);
HSSFRow row = sheet.createRow(0);
/*创建第一行表头*/
for (short i = 0; i < headers.length; i++) {
HSSFCell cell = row.createCell(i);
HSSFRichTextString text = new HSSFRichTextString(headers[i]);
cell.setCellValue(text);
}
Iterator it = list.iterator();
int index = 0;
while (it.hasNext()) {
index++;
row = sheet.createRow(index);
T t = (T) it.next();
/*反射得到字段*/
Field[] fields = t.getClass().getDeclaredFields();
/*如果需要匹配*/
if (CollectionUtils.isNotEmpty(containBean)) {
for (int j = 0; j < containBean.size(); j++) {
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
if (!field.getName().equals(containBean.get(j)))
continue;
/*给每一列set值*/
setCellValue(t, field, row, j);
}
}
} else {
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
setCellValue(t, field, row, i);
}
}
}
/*application/vnd.ms-excel告诉浏览器要下载的是个excel*/
response.setContentType("application/vnd.ms-excel;charset=UTF-8");
/*请求头设置，Content-Disposition为下载标识，attachment标识以附件方式下载*/
response.addHeader("Content-Disposition", "attachment;filename=" + new String((title).getBytes(), "ISO8859-1") + ".xls");
workbook.write(response.getOutputStream());
} finally {
if (workbook != null) {
workbook.close();
}
}
}
/**
* 设置每一行中的列
*
* @param t
* @param field
* @param row
* @param index
* @param
*/
private static void setCellValue(T t, Field field, HSSFRow row, int index) {
HSSFCell cell = row.createCell(index);
Object value = invoke(t, field);
String textValue = null;
if (value != null) {
if (value instanceof Date) {
Date date = (Date) value;
textValue = DateFormatUtils.format(date, "yyyy-MM-dd HH:mm:ss");
} else {
textValue = value.toString();
}
}
if (textValue != null) {
cell.setCellValue(textValue);
}
}
/**
* 反射映射数据集字段
*
* @param t
* @param field
* @param
* @return
*/
private static Object invoke(T t, Field field) {
try {
String fieldName = field.getName();
PropertyDescriptor pd = new PropertyDescriptor(fieldName, t.getClass());
Method method = pd.getReadMethod();
return method.invoke(t);
} catch (Exception e) {
return null;
}
}
} 
@ResponseBody
@RequestMapping(value = "/fileport", method = RequestMethod.GET)
public void filePort(HttpServletResponse response) {
//导出的表名
String title = "测试导出活动参与记录";
//表中第一行表头字段
String[] headers = {"主键id", "用户名", "活动id", "奖品id", "中奖时间"};
//实际数据结果集
List listObject = userRewardDao.queryUserActivityInfo("2018shuangdan_act", "2018shuangdan_evt", "sdthanks");
//具体需要写入excel需要哪些字段，这些字段取自UserReward类，也就是上面的实际数据结果集的泛型
List listColumn = Arrays.asList("id", "username", "actId", "rewardId", "winRewardTime");
try {
FilePortUtil.exportExcel(response, title, headers, listObject, listColumn);
} catch (Exception e) {
e.printStackTrace();
}
} 如上代码实际项目中都能使用，如有问题欢迎留言哈~
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