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通过反射来读取写入Excel
添加依赖
<!-- excel操作 -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>4.0.1</version>
</dependency>
代码
package com.pibgstar.demo.utils;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import javax.xml.crypto.Data;
import java.beans.PropertyDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;
/**
* @author pibigstar
* @create 2018-12-04 16:44
* @desc Excel工具类
**/
public class ExcelUtil {
/**
* @Author:pibigstar
* @Description: 读取Excel数据到集合中
*/
public static <T> List<T> readExcel(String filePath, Class<T> clazz) {
List<T> list = new ArrayList<>();
try {
FileInputStream fis = new FileInputStream(filePath);
Field[] fields = clazz.getDeclaredFields();
Workbook workbook = null;
if (filePath.endsWith(".xlsx")) {
workbook = new XSSFWorkbook(fis);
} else {
workbook = new HSSFWorkbook(fis);
}
Sheet sheet = workbook.getSheetAt(0);
int startNum = sheet.getFirstRowNum() + 1;//去掉表头
int endNum = sheet.getLastRowNum();
int colNum = fields.length; // 列数
for (int i = startNum; i <= endNum; i++) {
Row row = sheet.getRow(i);
T t = clazz.newInstance();
for (int j = 0; j < colNum; j++) {
Field field = fields[j];
Cell cell = row.getCell(j);
field.setAccessible(true);
String value = getValue(cell);
setValue(t, field, value);
}
list.add(t);
}
} catch (Exception e) {
e.printStackTrace();
}
return list;
}
/**
* @Author:pibigstar
* @Description: 为字段赋值
*/
private static <T> void setValue(T t, Field field, String value) {
Class<?> type = field.getType();
Object fieldValue = null;
if (type.equals(String.class)) {
fieldValue = value;
} else if (type.equals(Integer.class)) {
fieldValue = Integer.parseInt(value);
} else if (type.equals(int.class)) {
fieldValue = Integer.parseInt(value);
} else if (type.equals(Boolean.class)) {
fieldValue = Boolean.parseBoolean(value);
} else if (type.equals(boolean.class)) {
fieldValue = Boolean.parseBoolean(value);
} else if (type.equals(Float.class)) {
fieldValue = Float.parseFloat(value);
} else if (type.equals(Double.class)) {
fieldValue = Double.parseDouble(value);
} else if (type.equals(Data.class)) {
fieldValue = DateUtil.parseYYYYMMDDDate(value);
}
try {
field.set(t, fieldValue);
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
/**
* @Author:pibigstar
* @Description: 得到此格的值
*/
private static String getValue(Cell cell) {
if (cell == null) return null;
String result = "";
CellType cellType = cell.getCellType();
switch (cell.getCellType()) {
case NUMERIC:
if (HSSFDateUtil.isCellDateFormatted(cell)) {
SimpleDateFormat format = new SimpleDateFormat("YYYY-MM-dd HH:mm:ss");
result = format.format(cell.getNumericCellValue());
return result;
}
case BOOLEAN:
result = String.valueOf(cell.getBooleanCellValue());
return result;
case STRING:
return cell.getStringCellValue();
}
return null;
}
/**
* @Author:pibigstar
* @Description: 将集合中对象导入到Excel中
*/
public static <T> void writeExcel(List<T> list, String outPath) {
int size = list.size();
if (size == 0) return;
T t = null;
String fileName = "";
FileOutputStream fos = null;
try {
if (outPath.contains("/")) {
fileName = outPath.substring(outPath.lastIndexOf("/") + 1, outPath.lastIndexOf("."));
} else {
fileName = outPath.substring(0, outPath.lastIndexOf("."));
}
Workbook workbook = new HSSFWorkbook();
// 创建表单
Sheet sheet = workbook.createSheet(fileName);
// 设置表头
t = list.get(0);
Class<?> clazz = t.getClass();
setTitle(sheet, workbook, clazz);
// 写入内容
for (int i = 0; i < size; i++) {
Row row = sheet.createRow(i + 1);
t = list.get(i);
Field[] fs = t.getClass().getDeclaredFields();
int colNum = fs.length;
PropertyDescriptor pd = null;
for (int j = 0; j < colNum; j++) {
Cell cell = row.createCell(j);
Field field = fs[j];
String fieldName = field.getName();
pd = new PropertyDescriptor(fieldName, t.getClass());
Method readMethod = pd.getReadMethod();
Object result = readMethod.invoke(t);
cell.setCellValue(result.toString());
}
}
fos = new FileOutputStream(outPath);
workbook.write(fos);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* @Author:pibigstar
* @Description: 设置表头
*/
private static void setTitle(Sheet sheet, Workbook workbook, Class<?> clazz) {
Row row = sheet.createRow(0);// 第一行为表头
//设置为居中加粗
CellStyle style = workbook.createCellStyle();
Font font = workbook.createFont();
font.setBold(true);
style.setFont(font);
Field[] fields = clazz.getDeclaredFields();
int colNum = fields.length;
for (int i = 0; i < colNum; i++) {
sheet.setColumnWidth(i, 20 * 256);
Cell cell = row.createCell(i);
Field field = fields[i];
cell.setCellValue(field.getName());
cell.setCellStyle(style);
}
}
}
测试
public class TestExcelUtil {
public static void main(String[] args) {
List<User> users = new ArrayList<>();
User user1 = new User();
user1.setId("1");
user1.setName("派大星");
User user2 = new User();
user2.setId("2");
user2.setName("海绵宝宝");
users.add(user1);
users.add(user2);
//ExcelUtil.writeExcel(users, "D://Document And Settings3//Admin//Desktop//test.xls");
System.out.println("done");
List<User> list = ExcelUtil.readExcel("D://Document And Settings3//Admin//Desktop//test.xls", User.class);
for (User u:list) {
System.out.println(u);
}
}
}
运行结果
done
User{id='1', name='派大星'}
User{id='2', name='海绵宝宝'}