java读取excel内容导出excel文件
1、导入maven依赖
<dependency>
<groupId>org.apache.poigroupId>
<artifactId>poiartifactId>
<version>3.17version>
dependency>
<dependency>
<groupId>org.apache.poigroupId>
<artifactId>poi-ooxmlartifactId>
<version>3.17version>
dependency>
<dependency>
<groupId>org.apache.poigroupId>
<artifactId>poi-ooxml-schemasartifactId>
<version>3.17version>
dependency>
2、添加Excel工具类
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.*;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.DecimalFormat;
import java.util.*;
public class ExportBeanExcel<T> {
/**
* 这是一个通用的方法，利用了JAVA的反射机制，可以将放置在JAVA集合中并且符号一定条件的数据以EXCEL 的形式输出
* title 表格标题名
* headersName 表格属性列名数组
* headersId 表格属性列名对应的字段---你需要导出的字段名（为了更灵活控制你想要导出的字段）
* dtoList 需要显示的数据集合,集合中一定要放置符合javabean风格的类的对象
* out 与输出设备关联的流对象，可以将EXCEL文档导出到本地文件或者网络中
*/
public void exportExcel(String title, List<String> headersName, List<String> headersId, List<T> dtoList, OutputStream out) throws IOException {
/*（一）表头--标题栏*/
Map<Integer, String> headersNameMap = new HashMap<>();
int key = 0;
for (int i = 0; i < headersName.size(); i++) {
if (!headersName.get(i).equals(null)) {
headersNameMap.put(key, headersName.get(i));
key++;
}
}
/*（二）字段*/
Map<Integer, String> titleFieldMap = new HashMap<>();
int value = 0;
for (int i = 0; i < headersId.size(); i++) {
if (!headersId.get(i).equals(null)) {
titleFieldMap.put(value, headersId.get(i));
value++;
}
}
/* （三）声明一个工作薄：包括构建工作簿、表格、样式*/
HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet = wb.createSheet(title);
sheet.setDefaultColumnWidth((short) 15);
// 生成一个样式
HSSFCellStyle style = wb.createCellStyle();
HSSFRow row = sheet.createRow(0);
// style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
HSSFCell cell;
Collection c = headersNameMap.values();//拿到表格所有标题的value的集合
Iterator<String> it = c.iterator();//表格标题的迭代器
/*（四）导出数据：包括导出标题栏以及内容栏*/
//根据选择的字段生成表头
short size = 0;
while (it.hasNext()) {
cell = row.createCell(size);
cell.setCellValue(it.next().toString());
cell.setCellStyle(style);
size++;
}
//表格标题一行的字段的集合
Collection zdC = titleFieldMap.values();
Iterator<T> labIt = dtoList.iterator();//总记录的迭代器
int zdRow = 0;//列序号
while (labIt.hasNext()) {//记录的迭代器，遍历总记录
int zdCell = 0;
zdRow++;
row = sheet.createRow(zdRow);
T l = (T) labIt.next();
// 利用反射，根据javabean属性的先后顺序，动态调用getXxx()方法得到属性值
Field[] fields = l.getClass().getDeclaredFields();//获得JavaBean全部属性
for (short i = 0; i < fields.length; i++) {//遍历属性，比对
Field field = fields[i];
String fieldName = field.getName();//属性名
Iterator<String> zdIt = zdC.iterator();//一条字段的集合的迭代器
while (zdIt.hasNext()) {//遍历要导出的字段集合
if (zdIt.next().equals(fieldName)) {//比对JavaBean的属性名，一致就写入，不一致就丢弃
String getMethodName = "get"
+ fieldName.substring(0, 1).toUpperCase()
+ fieldName.substring(1);//拿到属性的get方法
Class tCls = l.getClass();//拿到JavaBean对象
try {
Method getMethod = tCls.getMethod(getMethodName,
new Class[]{});//通过JavaBean对象拿到该属性的get方法，从而进行操控
Object val = getMethod.invoke(l, new Object[]{});//操控该对象属性的get方法，从而拿到属性值
String textVal = null;
if (val != null) {
textVal = String.valueOf(val);//转化成String
} else {
textVal = null;
}
row.createCell((short) zdCell).setCellValue(textVal);//写进excel对象
zdCell++;
} catch (SecurityException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
}
}
}
wb.write(out);
}
/**
* Excel读取 操作
*/
public static List<List<String>> readExcel(InputStream is)
throws IOException {
Workbook wb = null;
try {
wb = WorkbookFactory.create(is);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (InvalidFormatException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
/** 得到第一个sheet */
Sheet sheet = wb.getSheetAt(0);
/** 得到Excel的行数 */
int totalRows = sheet.getPhysicalNumberOfRows();
/** 得到Excel的列数 */
int totalCells = 0;
if (totalRows >= 1 && sheet.getRow(0) != null) {
totalCells = sheet.getRow(0).getPhysicalNumberOfCells();
}
List<List<String>> dataLst = new ArrayList<List<String>>();
/** 循环Excel的行 */
for (int r = 0; r < totalRows; r++) {
Row row = sheet.getRow(r);
if (row == null)
continue;
List<String> rowLst = new ArrayList<String>();
/** 循环Excel的列 */
for (int c = 0; c < totalCells; c++) {
Cell cell = row.getCell(c);
String cellValue = "";
if (null != cell) {
/*HSSFDataFormatter hSSFDataFormatter = new HSSFDataFormatter();
cellValue= hSSFDataFormatter.formatCellValue(cell);*/
// 以下是判断数据的类型
CellType type = cell.getCellTypeEnum();
switch (type) {
case NUMERIC: // 数字
Double d = cell.getNumericCellValue();
DecimalFormat df = new DecimalFormat("#.#########");
cellValue = df.format(d);
break;
case STRING: // 字符串
cellValue = cell.getStringCellValue();
break;
case BOOLEAN: // Boolean
cellValue = cell.getBooleanCellValue() + "";
break;
case FORMULA: // 公式
try {
cellValue = cell.getStringCellValue();
} catch (IllegalStateException e) {
cellValue = String.valueOf(cell.getNumericCellValue());
}
break;
/* cellValue = cell.getCellFormula() + "";
break;*/
case BLANK: // 空值
cellValue = "";
break;
case _NONE: // 故障
cellValue = "非法字符";
break;
default:
cellValue = "未知类型";
break;
}
}
rowLst.add(cellValue);
}
/** 保存第r行的第c列 */
dataLst.add(rowLst);
}
return dataLst;
}
}
3、读取Excel文件
public void read() throws Exception {
File file = new File("/home/test.xlsx");
if (!file.exists()) {
throw new Exception("文件不存在!");
}
try (FileInputStream fileInputStream = new FileInputStream(file)) {
List<List<String>> lists = ExportBeanExcel.readExcel(fileInputStream);
//判断集合是否为空
if (!CollectionUtils.isEmpty(lists)) {
for (int i = 1; i < lists.size(); i++) {
List<String> list = lists.get(i);
System.out.println(list);
}
}
}
}
读取结果输出
4、导出Excel文件
public void export() throws Exception {
List<String> headerName = new ArrayList<>();
headerName.add("姓名");
headerName.add("性别");
headerName.add("年龄");
List<String> headersId = new ArrayList<>();
headersId.add("name");
headersId.add("sex");
headersId.add("age");
List<User> maps = new ArrayList<>();
for (int i = 0; i < 10; i++) {
maps.add(new User("小天","男",i));
}
File file = new File("/home/test.xlsx");
try (FileOutputStream fileOutputStream = new FileOutputStream(file);) {
ExportBeanExcel<User> excel = new ExportBeanExcel<>();
excel.exportExcel("test", headerName, headersId, maps, fileOutputStream);
}
}
导出结果
