官网下载poi相关jar包

我这里使用的版本是4.0.1

解压后选取需要的jar包

接下来就是熟悉的构建工程了，将jar包文件放到lib目录下

二：先来做一个简单的demo

public class Demo {

	public static void main(String [] args){
		//1.创建workbook
		HSSFWorkbook workbook = new HSSFWorkbook();
		//2.创建sheet
		HSSFSheet sheet = workbook.createSheet("学生信息");
		//3.创建行（下标从0开始）
		HSSFRow row = sheet.createRow(0);
		//4.创建列
		HSSFCell cell = row.createCell(0);
		//5.填充列
		cell.setCellValue("test");
		//6.文件输出
		try {
			OutputStream out = new FileOutputStream("D:/student.xls");
			workbook.write(out);
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

三：书写通用工具类

/**
 * Excel常用工具类
 * @author liuxiang
 *
 */
public class ExcelUtil {
/**
 * 将Excel数据导出到excel
 * @param data
 * @param out
 * @param field
 */
	//每页显示条数
	private static int sheetSize = 5000;
	//导出
	public static <T> void listToExcel(List<T> data,
			OutputStream out,Map<String, String> fields) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException, IOException{
		if(data==null||data.size()==0){
			throw new RuntimeException("传入的数据源中无数据！");			
		}
		//xls格式的excel不能存储太多的数据，最大65536
		HSSFWorkbook workbook = new HSSFWorkbook();
		//1.计算一共有多少sheet(页)
		int sheetNum = data.size()/sheetSize;
		if(data.size()%sheetSize!=0){
			sheetNum+=1;
		}
		//字段名和中文名分别存储在两个数组
		String[] fieldNames = new String[fields.size()];
		String[] chinaNames = new String[fields.size()];
		int count = 0;
		for(Entry<String,String> entry:fields.entrySet()){
			String fieldName = entry.getKey();
			String chinaName = entry.getValue();
			fieldNames[count] = fieldName;
			chinaNames[count] = chinaName;
			count++;
		}
		//填充属性
		for(int i=0;i<sheetNum;i++){
			int rowCount = 0;
			HSSFSheet sheet = workbook.createSheet();
			int startIndex = i*sheetSize;//0 5000
			int endIndex;
			if(i==sheetNum-1){
				if(data.size()%sheetSize!=0){
					endIndex = startIndex + data.size()%sheetSize -1;
				}else{
					endIndex = (i+1)*sheetSize - 1;
				}
			}else{
				endIndex = (i+1)*sheetSize - 1;
			}
			//endIndex = (i+1)*sheetSize - 1>=data.size()?data.size()-1:(i+1)*sheetSize - 1;//4999 9999	
			//创建行10 0-2 3-5 6-8 9
			HSSFRow row = sheet.createRow(rowCount);
			for(int j=0;j<chinaNames.length;j++){
				HSSFCell cell = row.createCell(j);
				cell.setCellValue(chinaNames[j]);//设置中文标题
			}
			rowCount++;
			for(int index=startIndex;index<=endIndex;index++){
				T item = data.get(index);
				row = sheet.createRow(rowCount);
				//通过反射取值
				for(int j=0;j<chinaNames.length;j++){
					Field field = item.getClass().getDeclaredField(fieldNames[j]);
					field.setAccessible(true);
					Object o = field.get(item);
				    String value = o==null?"":o.toString();
				    HSSFCell cell = row.createCell(j);
				    cell.setCellValue(value);//设置单元格内容
				}
				rowCount++;
			}
		}
		workbook.write(out);
		out.close();
	}
	/**
	 * 导入
	 * @param in
	 * @return
	 * @throws FileNotFoundException
	 * @throws IOException
	 */
	public static <T> List<T> excelToList(InputStream in) throws FileNotFoundException, IOException{
		List<Student> data = new ArrayList<Student>();
		HSSFWorkbook workbook = new HSSFWorkbook(in);
		//迭代每一个选项卡
		for(int i=0;i<workbook.getNumberOfSheets();i++){
			HSSFSheet sheet = workbook.getSheetAt(i);
			if(sheet==null){
				continue;
			}
			//循环行
			for(int j=1;j<=sheet.getLastRowNum();j++){
				HSSFRow row = sheet.getRow(j);
				if(row==null){
					continue;
				}
				Student stu = new Student();
				stu.setNo(row.getCell(0).getStringCellValue());
				stu.setName(row.getCell(1).getStringCellValue());
				stu.setAge(Integer.valueOf(row.getCell(2).getStringCellValue()));
				stu.setSex(row.getCell(3).getStringCellValue());
				data.add(stu);
			}
		}
		return (List<T>) data;
	}
}

四：测试程序

程序中这段代码原来使用的是HashMap ，这样会导致生成的EXCEL 数据列随机排列，换成LinkedHashMap 可以有序排列

Map<String,String> fields = new LinkedHashMap<String,String>();

public class Test {

	public static void main(String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException, IOException {
		List<Student> data = new ArrayList<Student>();
		Student stu;
		stu = new Student();
		stu.setName("one");
		stu.setNo("1");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("two");
		stu.setNo("2");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("three");
		stu.setNo("3");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("four");
		stu.setNo("4");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("five");
		stu.setNo("5");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("six");
		stu.setNo("6");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("seven");
		stu.setNo("7");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("eight");
		stu.setNo("8");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("nine");
		stu.setNo("9");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		stu = new Student();
		stu.setName("ten");
		stu.setNo("10");
		stu.setSex("男");
		stu.setAge(0);
		data.add(stu);
		OutputStream out = new FileOutputStream("D:/student.xls");
		Map<String,String> fields = new LinkedHashMap<String,String>();
		fields.put("no", "学号");
		fields.put("name", "姓名");
		fields.put("age", "年龄");
		fields.put("sex", "性别");
		ExcelUtil.listToExcel(data, out, fields);
		FileInputStream in = new FileInputStream("D:/student.xls");
		List<Student> list = ExcelUtil.excelToList(in);
		for(Student student:list){
			System.out.println(student.toString());			
		}
	}

}

五：测试结果

修改sheetSize 测试分页情况

sheetSize = 5000;