Java生成excel表格

导入实体的类的list和文件输出流生成XX.slx文件

import java.io.IOException;import java.io.OutputStream;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.text.SimpleDateFormat;import java.util.Date;import java.util.List;import org.apache.poi.hssf.usermodel.HSSFCell;import org.apache.poi.hssf.usermodel.HSSFCellStyle;import org.apache.poi.hssf.usermodel.HSSFRow;import org.apache.poi.hssf.usermodel.HSSFSheet;import org.apache.poi.hssf.usermodel.HSSFWorkbook;public class ExcelBuilder<T> {    @SuppressWarnings("unchecked")    public void buildExcel(List<T> list, OutputStream out) {        //如果列表为空就不生成表        if (list.isEmpty()) {return;}        Object entity = null;        Class<T> entityClass = null;        Field[] fields = null;        HSSFWorkbook workbook = null;        HSSFSheet sheet = null;        HSSFCellStyle style = null;        HSSFRow row = null;        HSSFCell cell = null;        int rowIndex = 0; //行计数        for (int count = 0; count <= list.size(); count++) { //循环比list的size多一次            if (rowIndex == 0) { //第一次获取泛型的类信息                entity = list.get(rowIndex);                System.out.println("第一个实体类：" + entity);                entityClass = (Class<T>) entity.getClass();                System.out.println("clazz = " + entityClass.getName()); //获取类名                fields = entityClass.getDeclaredFields();                System.out.println("fieldsNumber = " + fields.length); //获取属性个数                for (Field field : fields) {                    System.out.println("fieldName = " + field.getName()); //获取每个属性名                }                workbook = new HSSFWorkbook(); ////创建excel文件和表                sheet = workbook.createSheet();                 style = workbook.createCellStyle();  // 创建一个居中格式                style.setAlignment(HSSFCellStyle.ALIGN_CENTER);                row = sheet.createRow(rowIndex); ////设置表头字段（首行）                for (short i = 0; i < fields.length; i++) {                    cell = row.createCell(i);                    cell.setCellStyle(style);                    cell.setCellValue(fields[i].getName());                }                rowIndex++;            }            else {                row = sheet.createRow(rowIndex);                for (short i = 0; i < fields.length; i++) {                    String name = null;                    String methodName = null;                    Method method = null;                                       Object fieldValue = null;                    try {                        name = fields[i].getName().substring(0, 1).toUpperCase() + fields[i].getName().substring(1);                        methodName = "get" + name;                        method = entityClass.getMethod(methodName);                        entity = list.get(count-1); //获取实体类                        fieldValue = method.invoke(entity);                    } catch (NoSuchMethodException e) {                        e.printStackTrace();                    } catch (SecurityException e) {                        e.printStackTrace();                    } catch (IllegalAccessException e) {                        e.printStackTrace();                    } catch (IllegalArgumentException e) {                        e.printStackTrace();                    } catch (InvocationTargetException e) {                        e.printStackTrace();                    }                    cell = row.createCell(i);                    cell.setCellStyle(style);                    if (fieldValue instanceof Integer) {                          Integer intValue = (Integer) fieldValue;                          cell.setCellValue(intValue);                    } else if (fieldValue instanceof Float) {                          float fValue = (Float) fieldValue;                          cell.setCellValue(fValue);                    } else if (fieldValue instanceof Double) {                          double dValue = (Double) fieldValue;                          cell.setCellValue(dValue);                      } else if (fieldValue instanceof Long) {                        long lValue = (Long) fieldValue;                        cell.setCellValue(lValue);                      } else if (fieldValue instanceof Boolean) {                          boolean bValue = (Boolean) fieldValue;                        cell.setCellValue(bValue?"男":"女"); //男生true                    }  else if (fieldValue instanceof Date)                      {                          Date date = (Date) fieldValue;                          SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");                          cell.setCellValue(sdf.format(date));                      } else {                        cell.setCellValue(fieldValue.toString());                    }                 }                rowIndex++;            }        }        try {            workbook.write(out);            out.close();        } catch (IOException e) {            e.printStackTrace();        }      }}