一、实现原理：
1. 前端查询列表数据并渲染至table(<table>...</table>)表格
2. 表格html代码传输至后台
3. 后台把html转成Excel输出流返回前端
4. 前端自动调用下载器完成下载
注：因为渲染之后的hmtl代码数据量有可能很大，因此要使用POST方式的form表单方式提交。
二、实现步骤：
1. 查询后台数据并且渲染至页面table在此忽略,直接用一下静态html代替:
<div id="table">
<table id="targetTable">
<thead>
<tr>
<th style="background: fuchsia;">名次</th>
<th>姓名</th>
<th>成绩</th>
</tr>
</thead>
<tbody>
<tr align="center">
<td>1</td>
<td>小明</td>
<td>100</td>
</tr>
<tr align="center">
<td>2</td>
<td>小红</td>
<td>95.5</td>
</tr>
</tbody>
</table>
</div>
2. 表格html传输至后台进行解析生成excel输出流:
<script language="JavaScript">
function makeFormSubmit(url, excelName, tableHtml) {
// 创建一个 form
var form1 = document.createElement("form");
// 添加到 body 中
document.body.appendChild(form1);
// 创建输入
var input = document.createElement("input");
input.name = "excelName";
input.value = excelName;
var input1 = document.createElement("input");
input1.name = "tableHtml";
input1.value = tableHtml;
// 将输入框插入到 form 中
form1.appendChild(input);
form1.appendChild(input1);
// form 的提交方式
form1.method = "POST";
// form 提交路径
form1.action = url;
//以附件方式 解决数据量大的问题
form1.enctype = "multipart/form-data";
// 对该 form 执行提交
form1.submit();
// 删除该 form
document.body.removeChild(form1);
}
function loadExcel() {
var tableHtml = document.getElementById('table').innerHTML;
makeFormSubmit("/admin/api/excel/loadExcel", "测试excel", tableHtml);
}
</script>
完整的hmtl页面代码:
<html>
<head>
<meta http-equiv="content-Type" content="text/html;charset=utf-8"/>
<script src="./xqf-js/jquery.min.js"></script>
<script language="JavaScript">
function makeFormSubmit(url, excelName, tableHtml) {
// 创建一个 form
var form1 = document.createElement("form");
// 添加到 body 中
document.body.appendChild(form1);
// 创建输入
var input = document.createElement("input");
input.name = "excelName";
input.value = excelName;
var input1 = document.createElement("input");
input1.name = "tableHtml";
input1.value = tableHtml;
// 将输入框插入到 form 中
form1.appendChild(input);
form1.appendChild(input1);
// form 的提交方式
form1.method = "POST";
// form 提交路径
form1.action = url;
//以附件方式 解决数据量大的问题
form1.enctype = "multipart/form-data";
// 对该 form 执行提交
form1.submit();
// 删除该 form
document.body.removeChild(form1);
}
function loadExcel() {
var tableHtml = document.getElementById('table').innerHTML;
makeFormSubmit("/admin/api/excel/loadExcel", "测试excel", tableHtml);
}
</script>
</head>
<body>
<div id="table">
<table id="targetTable">
<thead>
<tr>
<th style="background: fuchsia;">名次</th>
<th>姓名</th>
<th>成绩</th>
</tr>
</thead>
<tbody>
<tr align="center">
<td>1</td>
<td>小明</td>
<td>100</td>
</tr>
<tr align="center">
<td>2</td>
<td>小红</td>
<td>95.5</td>
</tr>
</tbody>
</table>
</div>
<a href="javascript:" onclick="loadExcel();">
<input id="Button1" type="button" value="导出" />
</a>
</body>
</html>
3. 后台转换代码:
必要的jar包，maven项目所以直接pom导入:
<!-- Excel导出相关 -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-examples</artifactId>
<version>3.8</version>
</dependency>
跨行元素元数据类：
package com.loanofficer.utils.excel;
/**
* 跨行元素元数据
*
*/
public class CrossRangeCellMeta {
public CrossRangeCellMeta(int firstRowIndex, int firstColIndex, int rowSpan, int colSpan) {
super();
this.firstRowIndex = firstRowIndex;
this.firstColIndex = firstColIndex;
this.rowSpan = rowSpan;
this.colSpan = colSpan;
}
private int firstRowIndex;
private int firstColIndex;
private int rowSpan;// 跨越行数
private int colSpan;// 跨越列数
int getFirstRow() {
return firstRowIndex;
}
int getLastRow() {
return firstRowIndex + rowSpan - 1;
}
int getFirstCol() {
return firstColIndex;
}
int getLastCol() {
return firstColIndex + colSpan - 1;
}
int getColSpan(){
return colSpan;
}
}
将html table 转成 excel类：
package com.loanofficer.utils.excel;
import java.io.File;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.util.CellRangeAddress;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
/**
* 将html table 转成 excel
*
* 记录下来所占的行和列，然后填充合并
*/
public class ConvertHtml2Excel {
/**
* html表格转excel
*
* @param tableHtml 如
* <table>
* ..
* </table>
* @return
*/
public static HSSFWorkbook table2Excel(String tableHtml) {
HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet = wb.createSheet();
HSSFCellStyle style = wb.createCellStyle();
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
List<CrossRangeCellMeta> crossRowEleMetaLs = new ArrayList<>();
int rowIndex = 0;
try {
Document data = DocumentHelper.parseText(tableHtml);
// 生成表头
Element thead = data.getRootElement().element("thead");
HSSFCellStyle titleStyle = getTitleStyle(wb);
if (thead != null) {
List<Element> trLs = thead.elements("tr");
for (Element trEle : trLs) {
HSSFRow row = sheet.createRow(rowIndex);
List<Element> thLs = trEle.elements("th");
makeRowCell(thLs, rowIndex, row, 0, titleStyle, crossRowEleMetaLs);
row.setHeightInPoints(17);
rowIndex++;
}
}
// 生成表体
Element tbody = data.getRootElement().element("tbody");
if (tbody != null) {
HSSFCellStyle contentStyle = getContentStyle(wb);
List<Element> trLs = tbody.elements("tr");
for (Element trEle : trLs) {
HSSFRow row = sheet.createRow(rowIndex);
List<Element> thLs = trEle.elements("th");
int cellIndex = makeRowCell(thLs, rowIndex, row, 0, titleStyle, crossRowEleMetaLs);
List<Element> tdLs = trEle.elements("td");
makeRowCell(tdLs, rowIndex, row, cellIndex, contentStyle, crossRowEleMetaLs);
row.setHeightInPoints(18);
rowIndex++;
}
}
// 合并表头
for (CrossRangeCellMeta crcm : crossRowEleMetaLs) {
sheet.addMergedRegion(new CellRangeAddress(crcm.getFirstRow(), crcm.getLastRow(), crcm.getFirstCol(), crcm.getLastCol()));
}
} catch (DocumentException e) {
e.printStackTrace();
}
//自动调整列宽
for (int i = 0; i < 15; i++) {
sheet.autoSizeColumn((short)i);
}
return wb;
}
/**
* 生产行内容
*
* @return 最后一列的cell index
*/
/**
* @param tdLs th或者td集合
* @param rowIndex 行号
* @param row POI行对象
* @param startCellIndex
* @param cellStyle 样式
* @param crossRowEleMetaLs 跨行元数据集合
* @return
*/
private static int makeRowCell(List<Element> tdLs, int rowIndex, HSSFRow row, int startCellIndex, HSSFCellStyle cellStyle,
List<CrossRangeCellMeta> crossRowEleMetaLs) {
int i = startCellIndex;
for (int eleIndex = 0; eleIndex < tdLs.size(); i++, eleIndex++) {
int captureCellSize = getCaptureCellSize(rowIndex, i, crossRowEleMetaLs);
while (captureCellSize > 0) {
for (int j = 0; j < captureCellSize; j++) {// 当前行跨列处理（补单元格）
row.createCell(i);
i++;
}
captureCellSize = getCaptureCellSize(rowIndex, i, crossRowEleMetaLs);
}
Element thEle = tdLs.get(eleIndex);
String val = thEle.getTextTrim();
if (StringUtils.isBlank(val)) {
Element e = thEle.element("a");
if (e != null) {
val = e.getTextTrim();
}
}
HSSFCell c = row.createCell(i);
if (NumberUtils.isNumber(val)) {
c.setCellValue(Double.parseDouble(val));
c.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
} else {
c.setCellValue(val);
}
c.setCellStyle(cellStyle);
int rowSpan = NumberUtils.toInt(thEle.attributeValue("rowspan"), 1);
int colSpan = NumberUtils.toInt(thEle.attributeValue("colspan"), 1);
if (rowSpan > 1 || colSpan > 1) { // 存在跨行或跨列
crossRowEleMetaLs.add(new CrossRangeCellMeta(rowIndex, i, rowSpan, colSpan));
}
if (colSpan > 1) {// 当前行跨列处理（补单元格）
for (int j = 1; j < colSpan; j++) {
i++;
row.createCell(i);
}
}
}
return i;
}
/**
* 获得因rowSpan占据的单元格
*
* @param rowIndex 行号
* @param colIndex 列号
* @param crossRowEleMetaLs 跨行列元数据
* @return 当前行在某列需要占据单元格
*/
private static int getCaptureCellSize(int rowIndex, int colIndex, List<CrossRangeCellMeta> crossRowEleMetaLs) {
int captureCellSize = 0;
for (CrossRangeCellMeta crossRangeCellMeta : crossRowEleMetaLs) {
if (crossRangeCellMeta.getFirstRow() < rowIndex && crossRangeCellMeta.getLastRow() >= rowIndex) {
if (crossRangeCellMeta.getFirstCol() <= colIndex && crossRangeCellMeta.getLastCol() >= colIndex) {
captureCellSize = crossRangeCellMeta.getLastCol() - colIndex + 1;
}
}
}
return captureCellSize;
}
/**
* 获得标题样式
*
* @param workbook
* @return
*/
private static HSSFCellStyle getTitleStyle(HSSFWorkbook workbook) {
short titlebackgroundcolor = HSSFColor.GREY_25_PERCENT.index;
short fontSize = 12;
String fontName = "宋体";
HSSFCellStyle style = workbook.createCellStyle();
style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
style.setBorderBottom((short) 1);
style.setBorderTop((short) 1);
style.setBorderLeft((short) 1);
style.setBorderRight((short) 1);
style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
style.setFillForegroundColor(titlebackgroundcolor);// 背景色
HSSFFont font = workbook.createFont();
font.setFontName(fontName);
font.setFontHeightInPoints(fontSize);
font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
style.setFont(font);
return style;
}
/**
* 获得内容样式
*
* @param wb
* @return
*/
private static HSSFCellStyle getContentStyle(HSSFWorkbook wb) {
short fontSize = 12;
String fontName = "宋体";
HSSFCellStyle style = wb.createCellStyle();
style.setBorderBottom((short) 1);
style.setBorderTop((short) 1);
style.setBorderLeft((short) 1);
style.setBorderRight((short) 1);
HSSFFont font = wb.createFont();
font.setFontName(fontName);
font.setFontHeightInPoints(fontSize);
style.setFont(font);
return style;
}
public static void main(String[] args) {
String c = new String("<table id=\"targetTable\">\n" +
" <thead>\n" +
" <tr align=\"center\">\n" +
" <th>名次</th>\n" +
" <th>姓名</th>\n" +
" <th>成绩</th>\n" +
" </tr>\n" +
" </thead>\n" +
" <tbody>\n" +
" <tr align=\"center\">\n" +
" <td>1</td>\n" +
" <td>小明</td>\n" +
" <td>100</td>\n" +
" </tr>\n" +
" <tr align=\"center\">\n" +
" <td>2</td>\n" +
" <td>小红</td>\n" +
" <td>95.5</td>\n" +
" </tr>\n" +
" </tbody>\n" +
"</table>");
HSSFWorkbook wb = table2Excel(c);
try {
FileOutputStream fos = new FileOutputStream(new File("1.xls"));
wb.write(fos);
fos.flush();
fos.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Controller类：
package com.loanofficer.web.api;
import com.loanofficer.utils.excel.ConvertHtml2Excel;
import org.apache.poi.hssf.usermodel.*;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
@Controller
@RequestMapping(value = "/api/excel")
public class ExcelController {
@PostMapping(value = "/loadExcel")
private void loadExcelGet(HttpServletRequest req, HttpServletResponse resp) {
try {
req.setCharacterEncoding("UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
// 设置文件的mime类型
resp.setContentType("application/vnd.ms-excel");
// 存储编码后的文件名
String excelName = "name";
// 存储文件名称
String n = req.getParameter("excelName");
try {
excelName = URLEncoder.encode(n, "utf-8");
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
}
resp.setHeader("content-disposition", "attachment;filename=" + excelName + ".xls;filename*=utf-8''" + excelName + ".xls");
String tableHtml = req.getParameter("tableHtml");
// 从session中删除saveExcelMsg属性
req.getSession().removeAttribute("saveExcelMsg");
// 定义一个输出流
ServletOutputStream sos = null;
HSSFWorkbook wb = ConvertHtml2Excel.table2Excel(tableHtml);
try {
// 保存到文件中
sos = resp.getOutputStream();
wb.write(sos);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (sos != null) {
try {
sos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}