web项目导出excel表格

该功能涉及到两个知识点，一是制作excel相关插件的使用，二是导出文件，spring-mvc该如何配置
先说excel插件的使用，这次使用的是org.apache.poi包，版本是3.9，下面粘完整能运行的代码
maven依赖

org.apache.poi
poi
3.9


插件的实体类，也可以理解为参数，这里采用了build设计模式，好处是初始化了一些默认值，使用的时候代码写的方便。针对表格导出，我觉得三个参数足够了，标题、表头以及数据，所以，这三个参数构造方法我设计的必传，其它使用默认参数
package com.util;

import java.util.List;

public class ExcelParam {
String name;
int width;
String font;
String[] headers;
/**
* 导出数据的样式
* 1:String left;
* 2:String center
* 3:String right
* 4 int right
* 5:float ###,###.## right
* 6:number: #.00% 百分比 right
*/
int[] ds_format;
/**
* 每列表格的宽度,默认为256 * 14
*/
int[] widths;
List data;

private ExcelParam() {

}
//使用Builder模式，设置默认参数和必填参数
public static class Builder {
String name;
int width = 256 * 14;
String font = "微软雅黑";
String[] headers;
int[] ds_format;
int[] widths;
List data;

public Builder(String name) {
this.name = name;
}

public Builder font(String font) {
this.font = font;
return this;
}

public Builder width(int width) {
this.width = width;
return this;
}

public Builder headers(String[] headers) {
this.headers = headers;
return this;
}

public Builder ds_format(int[] ds_format) {
this.ds_format = ds_format;
return this;
}

public Builder widths(int[] widths) {
this.widths = widths;
return this;
}

public Builder data(List data) {
this.data = data;
return this;
}

public ExcelParam build() {
ExcelParam excelParam = new ExcelParam();
excelParam.name = this.name;
excelParam.data = this.data;
excelParam.widths = this.widths;
excelParam.ds_format = this.ds_format;
excelParam.headers = this.headers;
excelParam.font = this.font;
excelParam.width = this.width;
return excelParam;
}
}
}
package com.ucredit.util;

import org.apache.poi.hssf.usermodel.*;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URLEncoder;

public class ExcelUtil {
private ExcelUtil() {
}

public static void export(ExcelParam excelParam, HttpServletResponse response) throws IOException {
if (excelParam.widths == null) {
excelParam.widths = new int[excelParam.headers.length];
for (int i = 0; i < excelParam.headers.length; i++) {
excelParam.widths[i] = excelParam.width;
}
}
if (excelParam.ds_format == null) {
excelParam.ds_format = new int[excelParam.headers.length];
for (int i = 0; i < excelParam.headers.length; i++) {
excelParam.ds_format[i] = 1;
}
}
//创建一个工作薄
HSSFWorkbook wb = new HSSFWorkbook();
//创建一个sheet
HSSFSheet sheet = wb.createSheet("excel");
int rowCount = 0;
if (excelParam.headers != null) {
HSSFRow row = sheet.createRow(rowCount);
//表头样式
HSSFCellStyle style = wb.createCellStyle();
HSSFFont font = wb.createFont();
font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
font.setFontHeightInPoints((short) 11);
style.setFont(font);
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);

for (int i = 0; i < excelParam.headers.length; i++) {
sheet.setColumnWidth(i, excelParam.widths[i]);
HSSFCell cell = row.createCell(i);
cell.setCellValue(excelParam.headers[i]);
cell.setCellStyle(style);
}
rowCount++;
}
HSSFCellStyle style = wb.createCellStyle();
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
//表格主体 解析list
for (int i = 0; i < excelParam.data.size(); i++) { //行数
HSSFRow row = sheet.createRow(rowCount);
for (int j = 0; j < excelParam.headers.length; j++) { //列数
HSSFCell cell = row.createCell(j);
cell.setCellValue(excelParam.data.get(i)[j]);
cell.setCellStyle(style);
}
rowCount++;
}
//设置文件名
String fileName = excelParam.name + ".xls";
response.setContentType("application/vnd.ms-excel");
response.setHeader("Content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
response.setHeader("Pragma", "No-cache");
OutputStream outputStream = response.getOutputStream();
wb.write(outputStream);
outputStream.flush();
outputStream.close();
}
}

其实从这个方法就能看出，文件最后导出，实际上是往response中的outputStream中写入文件，之后的工作是由浏览器来完成的
controller层写法
@RequestMapping(value = "download")
public void download(@RequestParam String username,
@RequestParam String operation_module,
@RequestParam String operation_type,
@RequestParam String start_time,
@RequestParam String end_time,
HttpServletResponse response) throws Exception {
List list = operationLogDao.get(username, operation_module, operation_type, start_time, end_time);
String[] heads = {"序号", "账号", "姓名", "操作类型", "操作模块", "处理员工号码", "处理结果", "登录IP", "时间", "所在城市"};
List data = new LinkedList<>();
for (int i = 0; i < list.size(); i++) {
OperationLogEntity entity = list.get(i);
String[] temp = new String[10];
temp[0] = String.valueOf(i + 1);
temp[1] = entity.getUsername();
temp[2] = entity.getName();
temp[3] = entity.getOperation_type();
temp[4] = entity.getOperation_module();
temp[5] = entity.getProcess_number();
temp[6] = entity.getProcess_result();
temp[7] = entity.getIp();
temp[8] = DateUtils.getDateBeforeOrAfterStrCN(entity.getOperation_time(), 0);
temp[9] = entity.getCity();
data.add(temp);
}
ExcelParam param = new ExcelParam.Builder("操作日志").headers(heads).data(data).build();
ExcelUtil.export(param, response);
}

实际使用
//这样写很简洁
ExcelParam param = new ExcelParam.Builder("操作日志").headers(heads).data(data).build();