java将list写入到excel中并导出到本地（POI）

1.数据库查询得到的对象列表为ObjectList

此处不展示

2.html页面导出按钮，当点击导出按钮后，post提交到js进行请求servlet

1）按钮的html代码：<input type="button" value="导出" class="btn btn-default " id="export" /> 

2）点击该按钮后，将参数进行验证，交给对应的js处理

①validate校验提交表单非空

function validate (el, type) {
if (!$(el).val() || $(el).val().length === 0) {
alert('请选择'+type);
return false;
}
return true;
}

②js处理代码，当校验非空后，ajax以post方式提交给对应的url（servlet），提交的参数序列化；当servlet请求为success时，打开url（get请求）

$('#export').click(function(){
if (!(
validate('#region', '城市') && 
validate('#accessType', '渠道') &&
validate('#status', '状态') &&
validate('#startTime', '开始时间') &&
validate('#endTime', '结束时间')
)) return;
$.ajax({
type: 'POST',
url: '/cac/robust/ExportExcelServlet',
data: $('#formper').serialize(),
success: function () {
window.location.href = '/cac/robust/ExportExcelServlet'
}
})
})

3.servlet代码 

import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLEncoder;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import com.ailk.toptea.cac.util.DataHelper;
import com.ailk.toptea.cac.util.ExcelUtils;
import com.ailk.toptea.cac.util.ListToMapUtils;
import com.ailk.toptea.cac.util.RegionNameUtil;

public class ExportExcelServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
 
//定义一个私有变量来存储查询到的对象列表
private List<TableJsonOne> tableJsonOnesPri = new ArrayList<>();

@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {

String zero = "0.000";
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
// 设置编码
try {

//数据库查询代码，此处不展示将私有变量赋值
tableJsonOnesPri = tableJsonOnes;
} catch (Exception e) {
logger.error("查询数据库错误", e);
}
}

@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
PrintWriter out = response.getWriter();
try {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");


List<String> sheetTitle = new ArrayList<>();
sheetTitle.add("SQl Results1");
sheetTitle.add("SQl Results2");
String[] rowsName = new String[] { "地市", "渠道", "状态", "状态", "日期", "前一天主体产品办理量", "日期", "当天主体产品办理量",
"当天产品办理环比增长率"};
List<Object[]> dataList = new ArrayList<>();
Object[] objs = null;

if (tableJsonOnesPri.isEmpty()) {
//如果数据为空

String a = URLEncoder.encode("导出数据为空，请稍后重试！", "UTF-8");
out.print("<script>alert(decodeURIComponent('" + a
+ "') );window.location.href='robustPercentOne.html'</script>");
out.close();

}else {
for (int i = 0; i < tableJsonOnesPri.size(); i++) {
TableJsonOne tjo = tableJsonOnesPri.get(i);
objs = new Object[rowsName.length];
objs[0] = tjo.getRegion();
objs[1] = tjo.getAccessType();
objs[2] = tjo.getStatus();
objs[3] = tjo.getChineseStatus();
objs[4] = tjo.getTime1();
objs[5] = tjo.getVv1();
objs[6] = tjo.getTime2();
objs[7] = tjo.getVv2();
objs[8] = Math.round(Float.parseFloat(tjo.getPercent()) * 1000) * 1.0 / 10 + "%";
logger.info("objs" + objs[8]);
// SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
// String date = df.format(man.getModiDate());
// objs[5] = date;
dataList.add(objs);
}

ExcelUtils ex = new ExcelUtils(sheetTitle, rowsName, dataList);
try {
ex.export(response);
} catch (Exception e) {
logger.info("报错", e);
String a = URLEncoder.encode("导出出错，请稍后重试！", "UTF-8");
out.print("<script>alert(decodeURIComponent('" + a
+ "') );window.location.href='robustPercentOne.html'</script>");
out.close();
}
}

} catch (Exception e) {
logger.info(e);
String a = URLEncoder.encode("导出出错，请稍后重试！", "UTF-8");
out.print("<script>alert(decodeURIComponent('" + a
+ "') );window.location.href='robustPercentOne.html'</script>");
out.close();
}


}
}

4.ExcelUtils工具类

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
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.HSSFRichTextString;
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;

/**
* 导出Excel公共方法
* @version 1.0
*
* @author wangcp
*
*/
public class ExcelUtils {

//显示的导出表的标题
private List<String> sheetTitle;
//导出表的列名
private String[] rowName ;

private List<Object[]> dataList = new ArrayList<Object[]>();
private Logger logger = Logger.getLogger(this.getClass());
HttpServletResponse response;

//构造方法，传入要导出的数据
public ExcelUtils(List<String> sheetTitle,String[] rowName,List<Object[]> dataList){
this.dataList = dataList;
this.rowName = rowName;
this.sheetTitle = sheetTitle;
}

/*
* 导出数据
* */
public void export(HttpServletResponse response) throws Exception{
try{
HSSFWorkbook workbook = new HSSFWorkbook(); // 创建工作簿对象
for (int i = 0; i < sheetTitle.size(); i++) {
HSSFSheet sheet = workbook.createSheet(sheetTitle.get(i)); // 创建工作表
// 产生表格标题行
// HSSFRow rowm = sheet.createRow(0);
// HSSFCell cellTiltle = rowm.createCell(0);

//sheet样式定义【getColumnTopStyle()/getStyle()均为自定义方法 - 在下面 - 可扩展】
HSSFCellStyle columnTopStyle = this.getColumnTopStyle(workbook);//获取列头样式对象
HSSFCellStyle style = this.getStyle(workbook); //单元格样式对象

// sheet.addMergedRegion(new CellRangeAddress(0, 1, 0, (rowName.length-1)));
// cellTiltle.setCellStyle(columnTopStyle);
// cellTiltle.setCellValue(title);

// 定义所需列数
int columnNum = rowName.length;
HSSFRow rowRowName = sheet.createRow(0); // 在索引2的位置创建行(最顶端的行开始的第二行)

// 将列头设置到sheet的单元格中
for(int n=0;n<columnNum;n++){
HSSFCell cellRowName = rowRowName.createCell(n); //创建列头对应个数的单元格
cellRowName.setCellType(HSSFCell.CELL_TYPE_STRING); //设置列头单元格的数据类型
HSSFRichTextString text = new HSSFRichTextString(rowName[n]);
cellRowName.setCellValue(text); //设置列头单元格的值
cellRowName.setCellStyle(columnTopStyle); //设置列头单元格样式
}

//将查询出的数据设置到sheet对应的单元格中
for(int k=0;k<dataList.size();k++){

Object[] obj = dataList.get(k);//遍历每个对象
HSSFRow row = sheet.createRow(k+1);//创建所需的行数

for(int j=0; j<obj.length; j++){
HSSFCell cell = null; //设置单元格的数据类型
// if(j == 0){
// cell = row.createCell(j,HSSFCell.CELL_TYPE_NUMERIC);
// cell.setCellValue(i+1);
// }else{
cell = row.createCell(j,HSSFCell.CELL_TYPE_STRING);
if(!"".equals(obj[j]) && obj[j] != null){
cell.setCellValue(obj[j].toString()); //设置单元格的值
}
// }
cell.setCellStyle(style); //设置单元格样式
}
}
//让列宽随着导出的列长自动适应
for (int colNum = 0; colNum < columnNum; colNum++) {
int columnWidth = sheet.getColumnWidth(colNum) / 256;
for (int rowNum = 0; rowNum < sheet.getLastRowNum(); rowNum++) {
HSSFRow currentRow;
//当前行未被使用过
if (sheet.getRow(rowNum) == null) {
currentRow = sheet.createRow(rowNum);
} else {
currentRow = sheet.getRow(rowNum);
}
if (currentRow.getCell(colNum) != null) {
HSSFCell currentCell = currentRow.getCell(colNum);
// logger.info("celltype:" + currentCell.getCellType());
if (currentCell.getCellType() == HSSFCell.CELL_TYPE_STRING) {
int length = currentCell.getStringCellValue().getBytes().length;
// logger.info("length:" + length);
if (columnWidth < length) {
columnWidth = length;
}
}
}
}
if(colNum == 0){
sheet.setColumnWidth(colNum, (columnWidth-2) * 256);
}else{
sheet.setColumnWidth(colNum, (columnWidth+4) * 256);
}
}


}

if(workbook !=null){
try
{
String fileName = "Excel-" + String.valueOf(System.currentTimeMillis()).substring(4, 13) + ".xls";
String headStr = "attachment; filename=\"" + fileName + "\"";
response.reset();
response.setContentType("APPLICATION/OCTET-STREAM");
response.setHeader("Content-Disposition", headStr);

OutputStream out = response.getOutputStream();
workbook.write(out);
}
catch (IOException e)
{
e.printStackTrace();
}
}

}catch(Exception e){
e.printStackTrace();
}

}

/*
* 列头单元格样式
*/
public HSSFCellStyle getColumnTopStyle(HSSFWorkbook workbook) {

// 设置字体
HSSFFont font = workbook.createFont();
//设置字体大小
font.setFontHeightInPoints((short)11);
//字体加粗
font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
//设置字体名字
font.setFontName("Courier New");
//设置样式;
HSSFCellStyle style = workbook.createCellStyle();
//设置底边框;
style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
//设置底边框颜色;
style.setBottomBorderColor(HSSFColor.BLACK.index);
//设置左边框;
style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
//设置左边框颜色;
style.setLeftBorderColor(HSSFColor.BLACK.index);
//设置右边框;
style.setBorderRight(HSSFCellStyle.BORDER_THIN);
//设置右边框颜色;
style.setRightBorderColor(HSSFColor.BLACK.index);
//设置顶边框;
style.setBorderTop(HSSFCellStyle.BORDER_THIN);
//设置顶边框颜色;
style.setTopBorderColor(HSSFColor.BLACK.index);
//在样式用应用设置的字体;
style.setFont(font);
//设置自动换行;
style.setWrapText(false);
//设置水平对齐的样式为居中对齐;
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
//设置垂直对齐的样式为居中对齐;
style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);

return style;

}

/*
* 列数据信息单元格样式
*/
public HSSFCellStyle getStyle(HSSFWorkbook workbook) {
// 设置字体
HSSFFont font = workbook.createFont();
//设置字体大小
//font.setFontHeightInPoints((short)10);
//字体加粗
//font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
//设置字体名字
font.setFontName("Courier New");
//设置样式;
HSSFCellStyle style = workbook.createCellStyle();
//设置底边框;
style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
//设置底边框颜色;
style.setBottomBorderColor(HSSFColor.BLACK.index);
//设置左边框;
style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
//设置左边框颜色;
style.setLeftBorderColor(HSSFColor.BLACK.index);
//设置右边框;
style.setBorderRight(HSSFCellStyle.BORDER_THIN);
//设置右边框颜色;
style.setRightBorderColor(HSSFColor.BLACK.index);
//设置顶边框;
style.setBorderTop(HSSFCellStyle.BORDER_THIN);
//设置顶边框颜色;
style.setTopBorderColor(HSSFColor.BLACK.index);
//在样式用应用设置的字体;
style.setFont(font);
//设置自动换行;
style.setWrapText(false);
//设置水平对齐的样式为居中对齐;
style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
//设置垂直对齐的样式为居中对齐;
style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);

return style;

}
}