• 使用apache的poi来实现数据导出到excel的功能——方式二


    此次,介绍利用poi与layui table结合导出excel。这次不需要从数据库中查询出来的数据进行每一行的拼接那么麻烦,我们这次将标题定义一个id值,对应从数据库中查找出来的字段名即可。

    1、pom.xml中引入所需要的依赖

    <!-- 处理Excel xlsx -->
        <dependency>
          <groupId>org.apache.poi</groupId>
          <artifactId>poi-ooxml</artifactId>
          <version>3.9</version>
        </dependency>
    
        <dependency>
          <groupId>org.mybatis.generator</groupId>
          <artifactId>mybatis-generator-core</artifactId>
          <version>1.3.5</version>
        </dependency>

    2、准备好工具文件——方法

    package com.test.util;
    
    import com.test.entity.common.OutPutModel;
    import java.io.OutputStream;
    import java.lang.reflect.Array;
    import java.lang.reflect.Field;
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import javax.servlet.http.HttpServletResponse;
    import org.apache.commons.lang3.ArrayUtils;
    import org.apache.commons.lang3.StringUtils;
    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;
    import org.apache.poi.ss.util.CellRangeAddress;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    
    /**
     * 
     * 报表导出公用方法
     */
    public class ExportExcel {
        public static final Logger logger = LoggerFactory.getLogger(ExportExcel.class);
        //显示的导出表的标题
        private String title;
    
        private String sheetName;
    
        private String fileName;
        //导出表的列名
        private String[] rowName ;
    
        private List<Object[]> dataList = new ArrayList<>();
    
        public ExportExcel(String title,String[] rowName,List<Object[]>  dataList,String fileName,String sheetName){
            this.dataList = dataList;
            this.rowName = rowName;
            this.title = title;
            this.fileName = fileName;
            this.sheetName = sheetName;
        }
        /*
         * 导出数据
         * */
        public void export(OutputStream out) throws Exception{
            try{
                HSSFWorkbook workbook = new HSSFWorkbook();                     // 创建工作簿对象
                HSSFSheet sheet = workbook.createSheet(sheetName);                  // 创建工作表
    
    
                //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
    
          int startIndex = 0;
          if(StringUtils.isNotBlank(title)){
            // 产生表格标题行
            HSSFRow rowm = sheet.createRow(0);
            HSSFCell cellTiltle = rowm.createCell(0);
    
            sheet.addMergedRegion(new CellRangeAddress(0, 1, 0, (rowName.length-1)));
            cellTiltle.setCellStyle(columnTopStyle);
            cellTiltle.setCellValue(title);
    
            startIndex += 2;
          }
    
                // 定义所需列数
                int columnNum = rowName.length;
                HSSFRow rowRowName = sheet.createRow(startIndex++);                // 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
                }
    
                if (dataList != null && dataList.size() > 0) {
                    //将查询出的数据设置到sheet对应的单元格中
                    for (int i = 0; i < dataList.size(); i++) {
    
                        Object[] obj = dataList.get(i);//遍历每个对象
                        HSSFRow row = sheet.createRow(i + startIndex);//创建所需的行数
    
                        for (int j = 0; j < obj.length; j++) {
                            HSSFCell cell;   //设置单元格的数据类型
                            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
                            }
                            //这段代码会导致第一列数据为数字排序
    //                    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) / 150;
                    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);
                        }
                        //这段代码会导致列宽过宽或过窄,现使用标准宽度
    //                    if (currentRow.getCell(colNum) != null) {
    //                        HSSFCell currentCell = currentRow.getCell(colNum);
    //                        if (currentCell.getCellType() == HSSFCell.CELL_TYPE_STRING) {
    //                            //如果页面的字段和查询结果的字段名称不匹配,这里会报空指针
    //                            //如果字段为null也会空指针
    //                                int length = currentCell.getStringCellValue().getBytes().length;
    //                            if (columnWidth < length) {
    //                                columnWidth = length;
    //                            }
    //                        }
    //                    }
                    }
                    if(colNum == 0){
                        sheet.setColumnWidth(colNum, (columnWidth-2) * 256);
                    }else{
                        sheet.setColumnWidth(colNum, (columnWidth+4) * 256);
                    }
                }
                workbook.write(out);
            }catch(Exception e){
                e.printStackTrace();
            }
    
        }
    
        /*
         * 列头单元格样式
         */
        private 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
         */
        private 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;
    
        }
    
        /**
         * controller中调用的方法
         */
        public static void controllerDownload(OutPutModel outPutModel, HttpServletResponse response, List<Object[]> list){
            //查询结果字段
            List<Map<String,String>> fieldList = outPutModel.getFieldList();
            //excel字段
            String[] rowName = null;
            //获取中文名称
            if(fieldList !=null && fieldList.size()>0) {
                rowName = new String[fieldList.size()];
                int i = 0;
                for (Map<String, String> map : fieldList) {
                    for (Map.Entry<String, String> entry : map.entrySet()) {
                        if("colcn".equals(entry.getKey())){
                            Array.set(rowName,i,entry.getValue());
                            i++;
                        }
                    }
                }
            }
            String fileName = "";
            if(StringUtils.isNotBlank(outPutModel.getFileName())){
                //excel文件名称,设置编码格式防止乱码
              fileName = StringUtil.changeEncode(outPutModel.getFileName()+".xls","ISO8859-1");
            }else{
                fileName = StringUtil.changeEncode(outPutModel.getTitle()+".xls","ISO8859-1");
            }
    
            if(StringUtils.isBlank(outPutModel.getSheetName())){
              outPutModel.setSheetName(outPutModel.getTitle());
            }
    
            String headStr = "attachment; filename="" + fileName+ """;
            response.setContentType("application/vnd.ms-excel");
            response.setHeader("Content-Disposition", headStr);
            OutputStream out;
            try {
                out = response.getOutputStream();
          ExportExcel ex = new ExportExcel(outPutModel.getTitle(), rowName, list,outPutModel.getFileName(), outPutModel.getSheetName());
                ex.export(out);
            } catch (Exception e) {
                logger.info(outPutModel.getTitle()+"下载出错");
            }
        }
    
    
        public static<T> List<Object[]> serviceDownload(OutPutModel outPutModel,List<T> list){
    
            List<Object[]> listData = new ArrayList<>();
            Object[] objects;
            List<Map<String,String>> fieldList = outPutModel.getFieldList();
            //excel字段
            String[] rowName = null;
            //获取英文名称
            if(fieldList !=null && fieldList.size()>0) {
                rowName = new String[fieldList.size()];
                int i = 0;
                for (Map<String, String> map : fieldList) {
                    //遍历map,将英文名获取并添加到数组中
                    for (Map.Entry<String, String> entry : map.entrySet()) {
                        if("colen".equals(entry.getKey())){
                            String value = entry.getValue();
                            Array.set(rowName,i,value);
                            i++;
                        }
                    }
                }
            }
    
            if(list !=null && list.size() > 0 && rowName != null){
                for(T t : list){
                    //存放结果值
                    objects = new Object[rowName.length];
                    //获取查询结果对象的字段集合
                    Field[] fields1 = t.getClass().getDeclaredFields();
                    //获取查询结果对象父类的字段集合
                    Field[] fields2 = t.getClass().getSuperclass().getDeclaredFields();
                    //合并数组
                    Field[] fields = ArrayUtils.addAll(fields1, fields2);
                    for (Field field : fields) {
                        //获取属性的名字
                        String name = field.getName();
                        for(int j=0;j<rowName.length;j++){
                            String rowNamei = rowName[j];
                            if (rowNamei.equals(name)) {
                                //将属性的首字符大写,方便构造get,set方法
                                name = name.substring(0, 1).toUpperCase() + name.substring(1);
                                try {
                                    //获得get方法
                                    Method method = t.getClass().getMethod("get" + name);
                                    //通过
                                    Array.set(objects,j, method.invoke(t)==null ||"".equals(method.invoke(t))?" ":method.invoke(t));
                                } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
                                    logger.info("获取get方法失败/n"+e.toString());
                                }
                            }
                        }
                    }
                    listData.add(objects);
                }
            }
            return listData;
        }
    
        /**
         * servieImpl中调用的下载方法,输入值为Map类型
         * @param outPutModel 导出字段model类
         * @param list<Map>类型的 导出结果
         * @return 处理后的数据
         */
        public static List<Object[]> serviceDownloadByMap(OutPutModel outPutModel,List<Map<String,Object>> list){
    
            List<Object[]> listData = new ArrayList<>();
            Object[] objects;
            List<Map<String,String>> fieldList = outPutModel.getFieldList();
            //excel字段
            String[] rowName = null;
            //获取英文名称
            if(fieldList !=null && fieldList.size()>0) {
                rowName = new String[fieldList.size()];
                int i = 0;
                for (Map<String, String> map : fieldList) {
                    //遍历map,将英文名获取并添加到数组中
                    for (Map.Entry<String, String> entry : map.entrySet()) {
                        if("colen".equals(entry.getKey())){
                            String value = entry.getValue();
                            Array.set(rowName,i,value);
                            i++;
                        }
                    }
                }
            }
    
            if(list !=null && list.size() > 0 && rowName != null){
                for(Map<String,Object> map : list){
                    //存放结果值
                    objects = new Object[rowName.length];
    
                        for(int j=0;j<rowName.length;j++){
                            String rowNamei = rowName[j];
                            for (Map.Entry<String, Object> entry : map.entrySet()) {
    //                            System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
                                if (rowNamei.equals(entry.getKey())) {
                                        Array.set(objects,j, null == entry.getValue()|| "".equals(entry.getValue()) ? " ":entry.getValue() );
                                }
                            }
    
                        }
                    listData.add(objects);
                }
            }
            return listData;
        }
    }

    准备好工具文件——属性

    package com.test.entity.common;
    
    import java.util.List;
    import java.util.Map;
    
    /**
     * Created by Test on 
     * 导出model
     */
    public class OutPutModel {
        //表头
        private String title;
        //文件名
        private String fileName;
        //工作薄名字
      private String sheetName;
        private String resultList;
    
        //查询结果
        private List<Map<String,String>> fieldList;
        //查询条件
        private Map<String,Object> queryList;
    
    
      public String getSheetName() {
        return sheetName;
      }
    
      public void setSheetName(String sheetName) {
        this.sheetName = sheetName;
      }
    
      public String getResultList() {
        return resultList;
      }
    
      public void setResultList(String resultList) {
        this.resultList = resultList;
      }
    
      public String getFileName() {
            return fileName;
        }
    
        public void setFileName(String fileName) {
            this.fileName = fileName;
        }
    
        public String getTitle() {
            return title;
        }
    
        public void setTitle(String title) {
            this.title = title;
        }
    
        public List<Map<String, String>> getFieldList() {
            return fieldList;
        }
    
        public void setFieldList(List<Map<String, String>> fieldList) {
            this.fieldList = fieldList;
        }
    
        public Map<String, Object> getQueryList() {
            return queryList;
        }
    
        public void setQueryList(Map<String, Object> queryList) {
            this.queryList = queryList;
        }
    }

    其中,属性类中的内容可以自定义的。

    3、jsp中使用的是layui,我们可以通过layui table的属性获取其中的标题集合,然后调用导出接口,实现导出。

     //=====================导出操作
                                    //1.获取标题头部内容
                                    var cols = [];
                                    $('.layui-table-header tr th').each(function(i,ths){
                                        if(i>0){
                                            var title = $(this).find('span:first').text();
                                            var filed = ths.getAttribute('data-field');
                                            if(filed != "customerId"){
                                                cols.push({colcn:title, colen:filed});
                                            }
    
                                        }
                                    })
                                    //2.组装
                                    var data = {
                                        title: '测试导出表格首行标题名',//不配置title的话,导出的excel文件没有文件头,从首行起就是列名
    fileName:'测试文件下载文件名',
                          sheetName:'导出excel的工作薄名称', fieldList: cols, resultList: JSON.stringify(judgeData) };
    //3.导出 postHref("${pageContext.request.contextPath}/testCtrl/outPutOrder",data); },

    4、后台接口controller层书写

     /**
       * 导出
       */
      @RequestMapping("/outPutCheckedOrder")
      @ResponseBody
      public String outPutCheckedOrder(String param, HttpServletResponse response){
        //json字符串转为javabean
        OutPutModel outPutModel = JSON.parseObject(param, OutPutModel.class);
        //获得查询结果
        String result = outPutModel.getResultList();
        List<Map<String,Object>> resultList = (List)JSONArray.parseArray(result);
        //利用工具将数据转型执行导出下载
        List<Object[]> list = ExportExcel.serviceDownloadByMap(outPutModel,resultList);
        ExportExcel.controllerDownload(outPutModel,response,list);
        return null;
      }

    完毕!

    注意:其中judgeData是在layui table中勾选过的数据,不需要在数据库中查询。

    那么,我们要是导出excel的标题自定义的怎么办呢?只需要在jsp中定义好标题即可。

    var cols = [
                              {colcn:'第一列', colen:'firstCol'}
                          ];
    package com.yjl.util;

    import com.yjl.entity.common.OutPutModel;
    import java.io.OutputStream;
    import java.lang.reflect.Array;
    import java.lang.reflect.Field;
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import javax.servlet.http.HttpServletResponse;
    import org.apache.commons.lang3.ArrayUtils;
    import org.apache.commons.lang3.StringUtils;
    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;
    import org.apache.poi.ss.util.CellRangeAddress;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;


    /**
    * Created by YJL on 2017/9/29.
    * 报表导出公用方法
    */
    public class ExportExcel {
    public static final Logger logger = LoggerFactory.getLogger(ExportExcel.class);
    //显示的导出表的标题
    private String title;

    private String sheetName;

    private String fileName;
    //导出表的列名
    private String[] rowName ;

    private List<Object[]> dataList = new ArrayList<>();

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

    public ExportExcel(String title,String[] rowName,List<Object[]> dataList,String fileName,String sheetName){
    this.dataList = dataList;
    this.rowName = rowName;
    this.title = title;
    this.fileName = fileName;
    this.sheetName = sheetName;
    }
    /*
    * 导出数据
    * */
    public void export(OutputStream out) throws Exception{
    try{
    HSSFWorkbook workbook = new HSSFWorkbook(); // 创建工作簿对象
    HSSFSheet sheet = workbook.createSheet(sheetName); // 创建工作表


    //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

    int startIndex = 0;
    if(StringUtils.isNotBlank(title)){
    // 产生表格标题行
    HSSFRow rowm = sheet.createRow(0);
    HSSFCell cellTiltle = rowm.createCell(0);

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

    startIndex += 2;
    }

    // 定义所需列数
    int columnNum = rowName.length;
    HSSFRow rowRowName = sheet.createRow(startIndex++); // 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
    }

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

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

    for (int j = 0; j < obj.length; j++) {
    HSSFCell cell; //设置单元格的数据类型
    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
    }
    //这段代码会导致第一列数据为数字排序
    // 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) / 150;
    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);
    }
    //这段代码会导致列宽过宽或过窄,现使用标准宽度
    // if (currentRow.getCell(colNum) != null) {
    // HSSFCell currentCell = currentRow.getCell(colNum);
    // if (currentCell.getCellType() == HSSFCell.CELL_TYPE_STRING) {
    // //如果页面的字段和查询结果的字段名称不匹配,这里会报空指针
    // //如果字段为null也会空指针
    // int length = currentCell.getStringCellValue().getBytes().length;
    // if (columnWidth < length) {
    // columnWidth = length;
    // }
    // }
    // }
    }
    if(colNum == 0){
    sheet.setColumnWidth(colNum, (columnWidth-2) * 256);
    }else{
    sheet.setColumnWidth(colNum, (columnWidth+4) * 256);
    }
    }
    workbook.write(out);
    }catch(Exception e){
    e.printStackTrace();
    }

    }

    /*
    * 列头单元格样式
    */
    private 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
    */
    private 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;

    }

    /**
    * controller中调用的方法
    */
    public static void controllerDownload(OutPutModel outPutModel, HttpServletResponse response, List<Object[]> list){
    //查询结果字段
    List<Map<String,String>> fieldList = outPutModel.getFieldList();
    //excel字段
    String[] rowName = null;
    //获取中文名称
    if(fieldList !=null && fieldList.size()>0) {
    rowName = new String[fieldList.size()];
    int i = 0;
    for (Map<String, String> map : fieldList) {
    for (Map.Entry<String, String> entry : map.entrySet()) {
    if("colcn".equals(entry.getKey())){
    Array.set(rowName,i,entry.getValue());
    i++;
    }
    }
    }
    }
    String fileName = "";
    if(StringUtils.isNotBlank(outPutModel.getFileName())){
    //excel文件名称,设置编码格式防止乱码
    fileName = StringUtil.changeEncode(outPutModel.getFileName()+".xls","ISO8859-1");
    }else{
    fileName = StringUtil.changeEncode(outPutModel.getTitle()+".xls","ISO8859-1");
    }

    if(StringUtils.isBlank(outPutModel.getSheetName())){
    outPutModel.setSheetName(outPutModel.getTitle());
    }

    String headStr = "attachment; filename="" + fileName+ """;
    response.setContentType("application/vnd.ms-excel");
    response.setHeader("Content-Disposition", headStr);
    OutputStream out;
    try {
    out = response.getOutputStream();
    ExportExcel ex = new ExportExcel(outPutModel.getTitle(), rowName, list,outPutModel.getFileName(), outPutModel.getSheetName());
    ex.export(out);
    } catch (Exception e) {
    logger.info(outPutModel.getTitle()+"下载出错");
    }
    }


    public static<T> List<Object[]> serviceDownload(OutPutModel outPutModel,List<T> list){

    List<Object[]> listData = new ArrayList<>();
    Object[] objects;
    List<Map<String,String>> fieldList = outPutModel.getFieldList();
    //excel字段
    String[] rowName = null;
    //获取英文名称
    if(fieldList !=null && fieldList.size()>0) {
    rowName = new String[fieldList.size()];
    int i = 0;
    for (Map<String, String> map : fieldList) {
    //遍历map,将英文名获取并添加到数组中
    for (Map.Entry<String, String> entry : map.entrySet()) {
    if("colen".equals(entry.getKey())){
    String value = entry.getValue();
    Array.set(rowName,i,value);
    i++;
    }
    }
    }
    }

    if(list !=null && list.size() > 0 && rowName != null){
    for(T t : list){
    //存放结果值
    objects = new Object[rowName.length];
    //获取查询结果对象的字段集合
    Field[] fields1 = t.getClass().getDeclaredFields();
    //获取查询结果对象父类的字段集合
    Field[] fields2 = t.getClass().getSuperclass().getDeclaredFields();
    //合并数组
    Field[] fields = ArrayUtils.addAll(fields1, fields2);
    for (Field field : fields) {
    //获取属性的名字
    String name = field.getName();
    for(int j=0;j<rowName.length;j++){
    String rowNamei = rowName[j];
    if (rowNamei.equals(name)) {
    //将属性的首字符大写,方便构造getset方法
    name = name.substring(0, 1).toUpperCase() + name.substring(1);
    try {
    //获得get方法
    Method method = t.getClass().getMethod("get" + name);
    //通过
    Array.set(objects,j, method.invoke(t)==null ||"".equals(method.invoke(t))?" ":method.invoke(t));
    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
    logger.info("获取get方法失败/n"+e.toString());
    }
    }
    }
    }
    listData.add(objects);
    }
    }
    return listData;
    }

    /**
    * servieImpl中调用的下载方法,输入值为Map类型
    * @param outPutModel 导出字段model
    * @param list<Map>类型的 导出结果
    * @return 处理后的数据
    */
    public static List<Object[]> serviceDownloadByMap(OutPutModel outPutModel,List<Map<String,Object>> list){

    List<Object[]> listData = new ArrayList<>();
    Object[] objects;
    List<Map<String,String>> fieldList = outPutModel.getFieldList();
    //excel字段
    String[] rowName = null;
    //获取英文名称
    if(fieldList !=null && fieldList.size()>0) {
    rowName = new String[fieldList.size()];
    int i = 0;
    for (Map<String, String> map : fieldList) {
    //遍历map,将英文名获取并添加到数组中
    for (Map.Entry<String, String> entry : map.entrySet()) {
    if("colen".equals(entry.getKey())){
    String value = entry.getValue();
    Array.set(rowName,i,value);
    i++;
    }
    }
    }
    }

    if(list !=null && list.size() > 0 && rowName != null){
    for(Map<String,Object> map : list){
    //存放结果值
    objects = new Object[rowName.length];

    for(int j=0;j<rowName.length;j++){
    String rowNamei = rowName[j];
    for (Map.Entry<String, Object> entry : map.entrySet()) {
    // System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
    if (rowNamei.equals(entry.getKey())) {
    Array.set(objects,j, null == entry.getValue()|| "".equals(entry.getValue()) ? " ":entry.getValue() );
    }
    }

    }
    listData.add(objects);
    }
    }
    return listData;
    }
    }
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  • 原文地址:https://www.cnblogs.com/yangyuke1994/p/10056831.html
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