1.首先获取Excel模板的路径，本例放在了项目中
String path = request.getSession().getServletContext().getRealPath("/") + File.separator + "WEB-INF" + File.separator + "templetfile" + File.separator;
String filename = "rolledlossData.xlsx";
2.获取XSSFWorkbook对象（XSSFWorkbook是操作Excel2007的版本，扩展名是.xlsx）
XSSFWorkbook workbook = new XSSFWorkbook(new FileInputStream(path+filename));
3.获取要导出的对象集合（对象属性要与表格中顺序、字段完全相同）
-----------本例中使用List<Object> list
4.将对象集合写到excel表中
Workbook wb =hssfWorkbook;
Sheet sheet = wb.getSheetAt(0);
Row row = null;
Cell cell;
Object data = null;
Object fieldValue = null;
SimpleDateFormat format = new SimpleDateFormat(defaultDateFormatPattern);
/** 写数据到excel **/
CellStyle dataStyle = createDataCellStyle(wb);
Field[] fields = list.get(0).getClass().getDeclaredFields();
int sums = list.size();
for (int rowIndex = 0; rowIndex < sums; rowIndex++) {
data = list.get(rowIndex);
row = sheet.createRow(rowIndex + 1);
int colums = fields.length;
for (int i=0;i<colums;i++){
cell = row.createCell(i);
cell.setCellStyle(dataStyle);
fieldValue = ReflectiveUtils.getValueByReflectField(data, fields[i]);
cell.setCellValue(convertObjectToString(fieldValue, format));
}
}
通过反射获取属性的值,并把属性值转换为 String 类型的方法
public static Object getValueByReflectField(Object data, Field field) {
try {
if(field == null){
return null;
}
field.setAccessible(true);
Object value = field.get(data);
return value;
} catch (SecurityException e) {
logger.error("通过反射获取类属性失败",e);
throw new RuntimeException("通过反射获取类属性失败",e);
}catch (IllegalArgumentException e) {
logger.error("通过反射获取对象值时，对象不合法",e);
throw new RuntimeException("通过反射获取对象值时，对象不合法",e);
} catch (IllegalAccessException e) {
logger.error("无法通过反射获取对象值，权限不足",e);
throw new RuntimeException("无法通过反射获取对象值，权限不足",e);
}
}
把对象转为String的方法
private static String convertObjectToString(Object value, DateFormat format) {
String strValue = null;
if (value instanceof Date) {
strValue = format.format(value);
} else if (value instanceof String) {
strValue = (String) value;
} else {
if (value == null) {
strValue = "";
} else {
strValue = value.toString();
}
}
return strValue;
}
5.将表格写入到流中
ByteArrayOutputStream byteOutput = new ByteArrayOutputStream(); wb.write(byteOutput); InputStream inputStream = new ByteArrayInputStream( byteOutput.toByteArray());
6.把文件流写到客户端（其中response为客户端请求HttpServletResponse response）
BufferedInputStream bin = null;
BufferedOutputStream bos = null;
GZIPOutputStream gzipOutput = null;
try {
/** 这里把文件名转换，否则中文乱码 **/
String fileName = new String(displayName.getBytes("GBK"),"ISO-8859-1");
// 清空response
response.reset();
//客服端使用保存文件的对话框
response.setHeader("Content-disposition", "attachment;filename="+fileName);
response.setHeader("Content-Encoding", "gzip");
response.setContentType("application/octet-stream");
bin = new BufferedInputStream(inputStream);
OutputStream out = response.getOutputStream();
bos = new BufferedOutputStream(out);
/** 这里使用gizp进行压缩 **/
gzipOutput = new GZIPOutputStream(bos);
byte[] buffer = new byte[512];
int readCount = -1;
while(true){
readCount = bin.read(buffer);
if(readCount == -1){
break;
}
gzipOutput.write(buffer,0,readCount);
}
}finally{
if(bin != null){
bin.close();
}
if(gzipOutput != null){
gzipOutput.close();
}
}