导入Excel——解析Excel——优化

package com.it.excel.excelLearn;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelUtil {
    public static List<ExcelSheetStructure> readExcel(String filePath) throws IOException {
        InputStream is = null;
        XSSFWorkbook xssfWorkbook = null;
        List<ExcelSheetStructure> sheetsDate = null;
        // 流读取Excel入内存
        is = new FileInputStream(filePath);
        xssfWorkbook = new XSSFWorkbook(is);
        sheetsDate = new ArrayList<>();
        // 遍历
        for (Sheet sheet : xssfWorkbook) {
            ExcelSheetStructure sheetStructure = new ExcelSheetStructure();
            // 获取sheet名字
            String sheetName = sheet.getSheetName();
            sheetStructure.setSheetName(sheetName);
            // 获取有效数据，开始行和结束行
            int firstRowNum = sheet.getFirstRowNum();
            int lastRowNum = sheet.getLastRowNum();
            // 读取数据
            List<Map<String, Object>> notHeaderList = new ArrayList<>();
            for (int i = firstRowNum; i <= lastRowNum; i++) {
                Row row = sheet.getRow(i);
                if (row == null) {
                    break;
                }
                // 处理表头一行数据
                if (i == firstRowNum) {
                    Map<String, Object> headerRowMap = getHeaderRowData(row);
                    sheetStructure.setSheetTableHeaderDate(headerRowMap);
                } else { // 非表头数据
                    Row headerRow = sheet.getRow(firstRowNum);
                    Map<String, Object> notHeaderRowMap = getNotHeaderRowData(row, headerRow);
                    notHeaderList.add(notHeaderRowMap);
                }
            }
            sheetStructure.setSheetTableList(notHeaderList);
            // 判断当前sheet是否有数据，如果没有，就打印sheetName,否则加入Excel数据结构中
            if (!sheetStructure.getSheetTableList().isEmpty() && !sheetStructure.getSheetTableHeaderDate().isEmpty()) {
                sheetsDate.add(sheetStructure);
            } else {
                System.out.println(sheetStructure.getSheetName());
            }
        }
        xssfWorkbook.close();
        is.close();
        return sheetsDate;
    }

    private static Map<String, Object> getNotHeaderRowData(Row row, Row headerRow) {
        Map<String, Object> rowMap = new HashMap<>();
        for (Cell cell : row) {
            /**
             * 设置单元格的类型是String,防止读取数据方法getStringCellValue()报错
             * 如果单元格中数据格式是数字类型:Cannot get a STRING value from a NUMERIC cell
             */
            cell.setCellType(CellType.STRING);
            String cellValue = cell.getStringCellValue();
            int columnIndex = cell.getColumnIndex();
            Cell currentHeaderCell = headerRow.getCell(columnIndex);
            // 存储：Map<"当前单元格对应的表头中文","当前单元格值">
            rowMap.put(currentHeaderCell.getRichStringCellValue().toString(), cellValue);
        }
        return rowMap;

    }

    private static Map<String, Object> getHeaderRowData(Row row) {
        Map<String, Object> headerMap = new HashMap<>();
        for (Cell cell : row) {
            cell.setCellType(CellType.STRING);
            String cellValue = cell.getStringCellValue();
            int columnIndex = cell.getColumnIndex();
            headerMap.put(String.valueOf(columnIndex), cellValue);
        }
        return headerMap;
    }
}