导出Excel的两种方法：
一，POI
导入poi包
poi-3.11-beta3-20141111.jar
1 /**
2 *
3 */
4 package com.car.ots.mpckp.utils;
5
6 import java.io.OutputStream;
7 import java.net.URLEncoder;
8 import java.util.List;
9
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12
13 import org.apache.commons.beanutils.BeanUtils;
14 import org.apache.poi.hssf.usermodel.HSSFCell;
15 import org.apache.poi.hssf.usermodel.HSSFCellStyle;
16 import org.apache.poi.hssf.usermodel.HSSFRow;
17 import org.apache.poi.hssf.usermodel.HSSFSheet;
18 import org.apache.poi.hssf.usermodel.HSSFWorkbook;
19
20 /**
21 * @author cora.guo
22 *
23 */
24 public class ExportUtils {
25
26 public static void createExcel(HttpServletRequest req,
27 HttpServletResponse resp, List<Object> datas, String sheetName,
28 List<String> headers, List<String> colunmValueNames)
29 throws Exception {
30 OutputStream out = null;
31 try {
32 // 第一步，创建一个webbook，对应一个Excel文件
33 resp.setContentType("application/vnd.ms-excel");
34 resp.setCharacterEncoding("UTF-8");
35 if (req.getHeader("User-Agent").toLowerCase().indexOf("msie") != -1) {
36 resp.setHeader("Content-Disposition", "attachment;filename="
37 + URLEncoder.encode(sheetName, "utf-8") + ".xls");
38 } else {
39 resp.setHeader("Content-Disposition", "attachment;filename="
40 + new String(sheetName.getBytes("utf-8"), "ISO-8859-1")
41 + ".xls");
42 }
43 resp.setHeader("Cache-Control", "max-age=0");
44 HSSFWorkbook wb = new HSSFWorkbook();
45
46 // 第二步，在webbook中添加一个sheet,对应Excel文件中的sheet
47 HSSFSheet sheet = wb.createSheet(sheetName);
48 // 第三步，在sheet中添加表头第0行,注意老版本poi对Excel的行数列数有限制short
49 HSSFRow row = sheet.createRow(0);
50 // 第四步，创建单元格，并设置值表头 设置表头居中
51 HSSFCellStyle style = wb.createCellStyle();
52 // 创建居中样式
53 style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
54 HSSFCell cell = null;
55 if (headers != null && headers.size() > 0) {
56 for (int i = 0; i < headers.size(); i++) {
57 cell = row.createCell(i);
58 cell.setCellValue(headers.get(i));
59 cell.setCellStyle(style);
60 }
61 }
62 // 第五步，写入实体数据 实际应用中这些数据从数据库得到，
63 if (datas != null && datas.size() != 0) {
64 for (int r = 0; r < datas.size(); r++) {
65 Object obj = datas.get(r);
66 row = sheet.createRow(r+1);
67 if (colunmValueNames != null
68 && colunmValueNames.size() != 0) {
69 for (int j = 0; j < colunmValueNames.size(); j++) {
70 String name = colunmValueNames.get(j);
71 String value = BeanUtils.getProperty(obj, name);
72 // 创建单元格,设置值
73 cell = row.createCell(j);
74 cell.setCellStyle(style);
75 cell.setCellValue(value);
76 }
77 }
78 }
79 }
80 out = resp.getOutputStream();
81 wb.write(out);
82 } catch (Exception e) {
83 // TODO Auto-generated catch block
84 throw new Exception(e);
85 } finally {
86 out.close();
87 }
88 }
89 }
二，JXl
导入包
1 package com.car.ots.uis.utils;
2
3 import java.net.URLEncoder;
4 import java.util.List;
5
6 import javax.servlet.http.HttpServletRequest;
7 import javax.servlet.http.HttpServletResponse;
8
9 import jxl.Workbook;
10 import jxl.format.Alignment;
11 import jxl.format.VerticalAlignment;
12 import jxl.write.Label;
13 import jxl.write.WritableCellFormat;
14 import jxl.write.WritableFont;
15 import jxl.write.WritableSheet;
16 import jxl.write.WritableWorkbook;
17
18 import org.apache.commons.beanutils.BeanUtils;
19
20 public class ExportUtil {
21 public static void export(HttpServletRequest req, HttpServletResponse resp, List<Object> datas,
22 String sheetName, List<String> headers, List<String> colunmValueNames) throws Exception {
23 // 写入excel
24 WritableWorkbook wb = null;
25 WritableSheet ws = null;
26 Label label = null;
27
28 try {
29 resp.setContentType("application/vnd.ms-excel");
30 resp.setCharacterEncoding("UTF-8");
31 if (req.getHeader("User-Agent").toLowerCase().indexOf("msie") != -1) {
32 resp.setHeader("Content-Disposition",
33 "attachment;filename=" + URLEncoder.encode(sheetName, "utf-8") + ".xls");
34 } else {
35 resp.setHeader("Content-Disposition",
36 "attachment;filename=" + new String(sheetName.getBytes("utf-8"), "ISO-8859-1") + ".xls");
37 }
38 resp.setHeader("Cache-Control", "max-age=0");
39 wb = Workbook.createWorkbook(resp.getOutputStream());
40
41 ws = wb.createSheet(sheetName, 0);
42
43 WritableFont bold_font = new WritableFont(WritableFont.ARIAL, 10, WritableFont.BOLD);
44 WritableCellFormat f = new WritableCellFormat(bold_font);
45 f.setVerticalAlignment(VerticalAlignment.CENTRE);
46 f.setAlignment(Alignment.CENTRE);
47 if(headers!=null&headers.size()!=0){
48 for (int i = 0; i < headers.size(); i++) {
49 ws.setColumnView(i, 25);
50 label = new Label(i, 0, headers.get(i), f);
51 ws.addCell(label);
52 }
53 }
54
55 WritableFont nobold_font = new WritableFont(WritableFont.ARIAL, 10, WritableFont.NO_BOLD);
56 f = new WritableCellFormat(nobold_font);
57 f.setVerticalAlignment(VerticalAlignment.CENTRE);
58 f.setAlignment(Alignment.CENTRE);
59 if(datas!=null&&datas.size()!=0){
60 for (int r = 0; r < datas.size(); r++) {
61 Object obj = datas.get(r);
62 if (colunmValueNames!=null&&colunmValueNames.size()!=0) {
63 for (int j = 0; j < colunmValueNames.size(); j++) {
64 String name = colunmValueNames.get(j);
65 String value = BeanUtils.getProperty(obj, name);
66 label = new Label(j, r + 1, value, f);
67 ws.addCell(label);
68 }
69 }
70 }
71 }
72 wb.write();
73 } catch (Exception e) {
74 throw new Exception(e);
75 } finally {
76 wb.write();
77 wb.close();
78
79 }
80 }
81
82 }
两者区别：
POI为apache公司的一个子项目,主要是提供一组操作windows文档的Java API
JavaExcel俗称jxl是一开放源码项目，通过它开发人员可以读取Excel文件的内容、创建新的Excel文件、更新已经存在的Excel文件。使用该API非Windows操作系统也可以通过纯Java应用来处理Excel数据表。因为是使用Java编写的，所以我们在Web应用中可以通过JSP、Servlet来调用API实现对Excel数据表的访问。
JVM虚拟机内存消耗的情况：
数据量3000条数据,每条60列.JVM虚拟机内存大小64M.
使用POI:运行到2800条左右就报内存溢出.
使用JXL:3000条全部出来,并且内存还有21M的空间.
可想而知,在对内存的消耗方面差距还是挺大的.
也许是由于JXL在对资源回收利用方面做的不错.
效率方面：
也是基于大数据量而言的,数据量小的话基本上差别不大,也不难被发觉.但是大的数据量,POI消耗的JVM内存远比JXL消耗的多.但相比提供的功能的话,JXL又相对弱了点.所以如果要实现的功能比较复杂的情况下可以考虑使用POI,但如果只想生成一些大数据量可以考虑使用JXL
时间： 2024-11-09 00:07:25