SXSSFWorkbook的簡單使用

在工做中使用到SXSSFWorkbook來導出Excel，寫一篇博客記錄一下SXSSFWorkbook的使用方法

1.介紹

SXSSFWorkbook是屬於apache基金會的Excel導出工具類，從其官網上能夠看出SXSSFWorkbook實現了Workbook接口

Streaming version of XSSFWorkbook implementing the "BigGridDemo" strategy. 
This allows to write very large files without running out of memory as 
only a configurable portion of the rows are kept in memory at any one time.

SXSSFWorkbook是實現「BigGridDemo」策略的XSSFWorkbook的流媒體版本。SXSSFWorkbook容許編寫很是大的文件而不會耗盡內存，
由於在任什麼時候候，只有可配置的一部分行保存在內存中。

2.使用

 首先咱們定義一個列的實體類，包含列的名稱，樣式等

import org.apache.poi.ss.usermodel.CellStyle; /** * @describe 定義excel列 * */
public class ExcelColumnInfo { private String columnName; private String columnCode; /** * 單元格樣式 */
    private CellStyle cellStyle; } public ExcelColumnInfo(String columnName, String columnCode) { super(); this.columnName = columnName; this.columnCode = columnCode; } public ExcelColumnInfo(String columnName, String columnCode, CellStyle cellStyle) { super(); this.columnName = columnName; this.columnCode = columnCode; this.cellStyle = cellStyle; } public String getColumnName() { return columnName; } public void setColumnName(String columnName) { this.columnName = columnName; } public String getColumnCode() { return columnCode; } public void setColumnCode(String columnCode) { this.columnCode = columnCode; } public CellStyle getCellStyle() { return cellStyle; } public void setCellStyle(CellStyle cellStyle) { this.cellStyle = cellStyle; } }

 

再定義一個Excel寫入單元格數據的工具類

/** * Excel輔助類 */
public class ExcelUtil { public static void setCell(Cell cell, Object obj) { if (obj == null) { cell.setCellValue(""); } else if (obj instanceof Integer) { cell.setCellValue((int) obj); } else if (obj instanceof BigDecimal) { cell.setCellValue(((BigDecimal) obj).doubleValue()); } else if (obj instanceof String) { cell.setCellValue((String) obj); } else if (obj instanceof Double) { cell.setCellValue((double) obj); } else if (obj instanceof Long) { cell.setCellValue((long) obj); } } public static void setCell(Cell cell, Object obj, CellStyle cellStyle) { cell.setCellStyle(cellStyle); if (obj instanceof Integer) { cell.setCellValue((int) obj); } else if (obj instanceof BigDecimal) { cell.setCellValue(((BigDecimal) obj).doubleValue()); } else if (obj instanceof String) { cell.setCellValue((String) obj); } else if (obj instanceof Double) { cell.setCellValue((double) obj); } else if (obj instanceof Long) { cell.setCellValue((long) obj); } else { cell.setCellValue(""); } } }

 

而後開始寫導出的方法

@Service public class ExportSystemLogService{ @Autowired private SystemLogMapper mapper; public SXSSFWorkbook exportExcel(Map<String, Object> params) throws IOException { SXSSFWorkbook wb = new SXSSFWorkbook(1000); //獲取表格列信息
        LinkedHashMap<String, List<ExcelColumnInfo>> excelInfo = getExcelInfo(wb); for(String sheetName : excelInfo.keySet()){ //建立sheet頁
            Sheet sheet = wb.createSheet(sheetName); //獲取該sheet頁的列信息
            List<ExcelColumnInfo> excelColumnInfo = excelInfo.get(sheetName); //生成Excel數據
 generateExcelData(sheet,excelColumnInfo,params); } return wb; } protected LinkedHashMap<String, List<ExcelColumnInfo>> getExcelInfo(Workbook wb) { LinkedHashMap<String, List<ExcelColumnInfo>> excelInfo = new LinkedHashMap<>(); List<ExcelColumnInfo> columns = new ArrayList<>(); CellStyle percentCellStyle = wb.createCellStyle(); //CellStyle wrapStyle = wb.createCellStyle(); //wrapStyle.setWrapText(true); //設置自動換行
 columns.add(new ExcelColumnInfo("日誌編號", "LOG_ID"));    //後面的columnCode與從數據庫中查詢出來的字段名一致
        columns.add(new ExcelColumnInfo("操做時間", "CREATE_TIME")); columns.add(new ExcelColumnInfo("操做人", "CREATE_USER")); columns.add(new ExcelColumnInfo("操做模塊", "OPERATION_MODULE")); columns.add(new ExcelColumnInfo("操做類型", "OPERATION_TYPE")); columns.add(new ExcelColumnInfo("詳情", "OPERATION_DETAIL")); columns.add(new ExcelColumnInfo("日誌級別", "LOG_LEVEL")); columns.add(new ExcelColumnInfo("備註", "REMARK")); excelInfo.put("系統日誌", columns); return excelInfo; } private void generateExcelData(Sheet sheet,List<ExcelColumnInfo> excelColumnInfo,Map<String, Object> params) { //設置列的寬度，第一個參數爲列的序號，從0開始，第二參數爲列寬，單位1/256個字節
        sheet.setColumnWidth(0, 12*256); sheet.setColumnWidth(2, 16*256); sheet.setColumnWidth(5, 12*256); sheet.setColumnWidth(6, 26*256); sheet.setColumnWidth(7, 26*256); //設置開始行和開始列
        int rowIndex = 0; int columnIndex = 0; Row row = sheet.createRow(rowIndex); //建立表頭
        for (ExcelColumnInfo column : excelColumnInfo) { ExcelUtil.setCell(row.createCell(columnIndex++), column.getColumnName()); } //獲取導出數據
        List<HashMap<String, Object>> data = mapper.getSystemLog(params); rowIndex = 1; for (HashMap<String, Object> tmp : data) { Row row1 = sheet.createRow(rowIndex); columnIndex = 0; for(ExcelColumnInfo column : excelColumnInfo){ Cell cell = row1.createCell(columnIndex); //設置單元格樣式
                if (column.getCellStyle() != null) { cell.setCellStyle(column.getCellStyle()); } ExcelUtil.setCell(cell,tmp.get(column.getColumnCode())); columnIndex++; } rowIndex++; } } }

 

其中Mapper接口與xml文件配置以下

@Mapper @Repository public interface SystemLogMapper { List<HashMap<String, Object>> getSystemLog(@Param("params") Map<String, Object> params);
 }

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.XXX.XXX.SystemLogMapper">
    
    <select id="getSystemLog" parameterType="java.util.HashMap" resultType="java.util.HashMap"> SELECT LOG_ID, CREATE_TIME, CREATE_USER, OPERATION_MODULE, OPERATION_TYPE, OPERATION_DETAIL, LOG_LEVEL, REMARK FORM SYSTEM_LOG ORDER BY CREATE_TIME DESC </select>
</mapper>

在調用時，只需在Controller層調用ExportSystemLogService.exportExcel(params)方法便可。