java poi技术操作excel之写Excel(向Excel中写入值)

写值到Excel：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;
import java.util.Map;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class WriteExcel {
private static final String EXCEL_XLS = "xls";
private static final String EXCEL_XLSX = "xlsx";

public static void writeExcel(List<Map> dataList, int cloumnCount,String finalXlsxPath){
OutputStream out = null;
try {
// 获取总列数
int columnNumCount = cloumnCount;
// 读取Excel文档
File finalXlsxFile = new File(finalXlsxPath);
Workbook workBook = getWorkbok(finalXlsxFile);
// sheet 对应一个工作页
Sheet sheet = workBook.getSheetAt(0);
/**
* 删除原有数据，除了属性列
*/
int rowNumber = sheet.getLastRowNum();	// 第一行从0开始算
System.out.println("原始数据总行数，除属性列：" + rowNumber);
for (int i = 1; i <= rowNumber; i++) {
Row row = sheet.getRow(i);
sheet.removeRow(row);
}
// 创建文件输出流，输出电子表格：这个必须有，否则你在sheet上做的任何操作都不会有效
out =  new FileOutputStream(finalXlsxPath);
workBook.write(out);
/**
* 往Excel中写新数据
*/
for (int j = 0; j < dataList.size(); j++) {
// 创建一行：从第二行开始，跳过属性列
Row row = sheet.createRow(j + 1);
// 得到要插入的每一条记录
Map dataMap = dataList.get(j);
String name = dataMap.get("BankName").toString();
String address = dataMap.get("Addr").toString();
String phone = dataMap.get("Phone").toString();
for (int k = 0; k <= columnNumCount; k++) {
// 在一行内循环
Cell first = row.createCell(0);
first.setCellValue(name);

Cell second = row.createCell(1);
second.setCellValue(address);

Cell third = row.createCell(2);
third.setCellValue(phone);
}
}
// 创建文件输出流，准备输出电子表格：这个必须有，否则你在sheet上做的任何操作都不会有效
out =  new FileOutputStream(finalXlsxPath);
workBook.write(out);
} catch (Exception e) {
e.printStackTrace();
} finally{
try {
if(out != null){
out.flush();
out.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
System.out.println("数据导出成功");
}

/**
* 判断Excel的版本,获取Workbook
* @param in
* @param filename
* @return
* @throws IOException
*/
public static Workbook getWorkbok(File file) throws IOException{
Workbook wb = null;
FileInputStream in = new FileInputStream(file);
if(file.getName().endsWith(EXCEL_XLS)){	 //Excel 2003
wb = new HSSFWorkbook(in);
}else if(file.getName().endsWith(EXCEL_XLSX)){	// Excel 2007/2010
wb = new XSSFWorkbook(in);
}
return wb;
}
}