首先我们约定存储格式：ArrayList<LinkedHashMap<String , Object>>，用LinkedHashMap<String , Object>来存储每条记录信息。具体参考方式见最下面代码
首先我们将上述格式转换成List<String[]>格式的数据，这样只要你符合上述的格式就可以导出任意的数据。具体代码如下
private static List<Object[]> mapDataset(HttpServletRequest request,
ArrayList<LinkedHashMap<String , Object>> allList, int len) {
trace.info("alllist------------------------------" + allList.size());
List<Object[]> dataset = new ArrayList<Object[]>();
if (allList == null) {
String str[] = new String[len];
dataset.add(str);
} else {
for (LinkedHashMap<String, Object> map : allList) {// 拿到第i个数据
//对第i个数组进行迭?
Iterator<Map.Entry<String, Object>> iter = map.entrySet().iterator();
int i = 0;
Object[] str = new Object[map.size()];// 保存数据的字符串数组
while (iter.hasNext()) {
Object value = iter.next().getValue();
if (value == null) {
str[i] = "";
} else {
str[i] = value;
}
i++;
}
dataset.add(str);
}
}
trace.info("数据大小"+dataset.size());
return dataset;
}然后我们将上述得到的List<String[]>类型数据dataset，利用POI写入excel当中，具体方法如下
public static void exportExcel(HttpServletRequest request,String rootPath, List<String> title, List<String[]> headers,
List<Object> dataList, OutputStream out) {
SXSSFWorkbook workbook = new SXSSFWorkbook ();
int sheetlen=dataList.size();
trace.info("一共生成"+sheetlen+"个表");
for (int i = 0; i<sheetlen; i++) {
// excel中生成一个表
String titles=title.get(i);
Sheet sheet =workbook.createSheet(titles);
//给表格加上边框，并且内容居中
CellStyle cellStyle= workbook.createCellStyle();
cellStyle.setAlignment(XSSFCellStyle.ALIGN_CENTER);
cellStyle.setBorderBottom(XSSFCellStyle.BORDER_THIN);
cellStyle.setBottomBorderColor(Font.BOLDWEIGHT_NORMAL);
cellStyle.setBorderLeft(XSSFCellStyle.BORDER_THIN);
cellStyle.setLeftBorderColor(Font.BOLDWEIGHT_NORMAL);
cellStyle.setBorderRight(XSSFCellStyle.BORDER_THIN);
cellStyle.setRightBorderColor(Font.BOLDWEIGHT_NORMAL);
cellStyle.setBorderTop(XSSFCellStyle.BORDER_THIN);
cellStyle.setTopBorderColor(HSSFColor.BLACK.index);
DataFormat format = workbook.createDataFormat();
cellStyle.setDataFormat(format.getFormat("@"));
Font titleFont = workbook.createFont();
titleFont.setFontHeightInPoints((short)10);
//titleFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
cellStyle.setAlignment(XSSFCellStyle.ALIGN_CENTER);
cellStyle.setVerticalAlignment(XSSFCellStyle.VERTICAL_CENTER);
cellStyle.setFont(titleFont);
String header[]=headers.get(i);
int len =header.length-1;
trace.info("表头的长度"+len);
// 设置第一行跨的行数，列数
sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, len));
Row row0 = sheet.createRow(0);
Cell ce = row0.createCell(0);
ce.setCellValue(titles);
ce.setCellStyle(cellStyle); // 样式，居�?
//生成表头信息
Row row = sheet.createRow(1);
int width1 = 0;
for (int k = 0; k <=len; k++){
Cell cell1 = row.createCell(k);
width1 = header[k].getBytes().length;
sheet.setColumnWidth(k,(width1*256*2));
XSSFRichTextString text = new XSSFRichTextString(header[k]);
cell1.setCellValue(text);
cell1.setCellStyle(cellStyle);
cell1.setCellType(Cell.CELL_TYPE_STRING);
}
/**
* 生成表格信息
*/
ArrayList<LinkedHashMap<String , Object>> listdata=(ArrayList<LinkedHashMap<String, Object>>) dataList.get(i);
List<Object[]> dataset = mapDataset(request, listdata, header.length);
Iterator<Object[]> it = dataset.iterator();
int index = 1;
while (it.hasNext()) {
index++;
row = sheet.createRow(index);
Object[] t = (Object[]) it.next();
for (int s = 0; s < t.length; s++) {
Cell cell = row.createCell(s);
// sheet.autoSizeColumn((short)i,true);
// 判断值的类型后进行强制类型转�?
if (t[s] instanceof Integer) {
cell.setCellStyle(cellStyle);
cell.setCellValue((Integer) t[s]);
} else if (t[s] instanceof Double) {
cell.setCellStyle(cellStyle);
cell.setCellValue(Double.parseDouble(t[s] + ""));
} else if (t[s] instanceof Float) {
cell.setCellStyle(cellStyle);
cell.setCellValue(Float.parseFloat(t[s] + ""));
} else {
String data = "";
if (t[s] != null && !"null".equals(t[s])
&& !"".equals(t[s])) {
data = t[s] + "";
}
if (isValidInt(data)) {
cell.setCellStyle(cellStyle);
cell.setCellValue(Integer.parseInt(data));
} else if (isValidDouble(data)) {
cell.setCellStyle(cellStyle);
cell.setCellValue(Double.parseDouble(data + ""));
} else if (isValidFloat(data)) {
cell.setCellStyle(cellStyle);
cell.setCellValue(Float.parseFloat(data + ""));
} else {
String textValue = data == null ? "" : (data + "");
XSSFRichTextString richString = new XSSFRichTextString(textValue);
cell.setCellValue(richString);
}
cell.setCellStyle(cellStyle);
}
}
}
}
try {
workbook.write(out);
} catch (IOException e) {
trace.error("exportExcel IOException " + e.getMessage());
}
} 最后我利用输出流，将文件导出，代码如下
public static synchronized String mapOutToExcel(HttpServletRequest request,
HttpServletResponse response,String filenames, List<String> title,List<String[]> headers,
List<Object> allList) {
OutputStream out = null;// 创建�?��输出流对�?
try {
/* 截取掉表名中多余的部�?*/
filenames = filenames.replaceAll(":", "-");
filenames = filenames.replaceAll("（", "(");
filenames = filenames.replaceAll("）", ")");
String subTitle = filenames;
String filename = new String((subTitle).getBytes("GB2312"),
"iso-8859-1");
// String filename=URLEncoder.encode((title+".xls"), "UTF-8");//IE
trace.info("@filename:=" + filename);
out = response.getOutputStream();//
response.setHeader("Content-disposition", "attachment; filename="
+ filename + ".xlsx");// filename是下载的xls的名，建议最好用英文
response.setContentType("application/octet-stream;charset=UTF-8");// 设置类型
response.setHeader("Pragma", "No-cache");// 设置�?
response.setHeader("Cache-Control", "no-cache");// 设置�?
response.setDateHeader("Expires", 0);// 设置日期�?
String rootPath = request.getSession().getServletContext()
.getRealPath("/");
exportExcel(request,rootPath, title, headers, allList, out);
out.flush();
} catch (IOException e) {
trace.error("OutToExcel OutputStream " + e.getMessage());
} finally {
try {
if (out != null) {
out.close();
}
} catch (IOException e) {
trace.error("OutToExcel OutputStream close " + e.getMessage());
}
}
return null;
}这里我们利用for循环实现导出测试
@RequestMapping(value="/excelPOI.html")
public void excelPOI(HttpServletRequest request,HttpServletResponse response){
BatchExportExcelUtil export=new BatchExportExcelUtil();
String filenames="POI导出的工具类";
List<String> title=new ArrayList<String>();
List<String[]> header=new ArrayList<String[]>();
List<LinkedHashMap<String,Object>> list1=new ArrayList<LinkedHashMap<String,Object>>();
List<Object> listall=new ArrayList<Object>();
String title1="你好啊";
String []head={"姓名","年龄","性别"};
title.add(title1);
header.add(head);
for(int i=0;i<=1000000;i++){
LinkedHashMap<String,Object> hashmap=new LinkedHashMap<String,Object>();
hashmap.put("name", "张三");
hashmap.put("age", "25");
hashmap.put("sex", "男");
list1.add(hashmap);
}
listall.add(list1);
export.mapOutToExcel(request, response, filenames, title, header, listall);
}以上是基于SSM框架实现的。