Java使用POI操作Excel文件

1、简介

　　Apache POI是Apache软件基金会的开放源码函式库，POI提供API给Java程序对Microsoft Office格式文件读和写的功能。

2、依赖的jar包

    <!-- excel 工具类 -->
    <dependencies>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.9</version>
        </dependency>

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.9</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml-schemas</artifactId>
            <version>3.9</version>
        </dependency>
    </dependencies>

3、POI读取EXCEL文件

　　---->读取指定的若干列单元格数据

        /**
         * description:读取xlsx文件指定的若干列单元格数据
　　　　  * args:指定的若干列的序号（列可以任意个）
         */
        @SuppressWarnings({ "resource", "unused" })
        public ArrayList<ArrayList<String>> xlsx_reader(String excel_url,int ... args) throws IOException {
            ArrayList<ArrayList<String>> ans=new ArrayList<ArrayList<String>>();
            File excelFile = null;
            InputStream is = null;
            try {
                 //读取xlsx文件
                XSSFWorkbook xssfWorkbook = null;
                //寻找目录读取文件
                excelFile = new File(excel_url);
                is = new FileInputStream(excelFile);
                xssfWorkbook = new XSSFWorkbook(is);              
                if(xssfWorkbook==null){
                    System.out.println("未读取到内容,请检查路径！");
                    return null;
                }                
                //遍历xlsx中的sheet
                for (int numSheet = 0; numSheet < xssfWorkbook.getNumberOfSheets(); numSheet++) {
                    XSSFSheet xssfSheet = xssfWorkbook.getSheetAt(numSheet);
                    if (xssfSheet == null) {
                        continue;
                    }
                    // 对于每个sheet，读取其中的每一行
                    for (int rowNum = 0; rowNum <= xssfSheet.getLastRowNum(); rowNum++) {
                        XSSFRow xssfRow = xssfSheet.getRow(rowNum);
                        if (xssfRow == null) continue; 
                        ArrayList<String> curarr=new ArrayList<String>();
                        for(int columnNum = 0 ; columnNum<args.length ; columnNum++){
                            XSSFCell cell = xssfRow.getCell(args[columnNum]);                            
                            curarr.add( Trim_str( getValue(cell) ) );
                        }
                        ans.add(curarr);
                    }
                }
            }catch(Exception e) {
                e.getStackTrace();
            }finally {
                  is.close();
            }
            return ans;
        }
        
        //判断后缀为xlsx的excel文件的数据类型
        @SuppressWarnings("deprecation")
        private static String getValue(XSSFCell xssfRow) {
            if(xssfRow==null){
                return "---";
            }
            if (xssfRow.getCellType() == xssfRow.CELL_TYPE_BOOLEAN) {
                return String.valueOf(xssfRow.getBooleanCellValue());
            } else if (xssfRow.getCellType() == xssfRow.CELL_TYPE_NUMERIC) {
                double cur=xssfRow.getNumericCellValue();
                long longVal = Math.round(cur);
                Object inputValue = null;
                if(Double.parseDouble(longVal + ".0") == cur)  
                        inputValue = longVal;  
                else  
                        inputValue = cur; 
                return String.valueOf(inputValue);
            } else if(xssfRow.getCellType() == xssfRow.CELL_TYPE_BLANK || xssfRow.getCellType() == xssfRow.CELL_TYPE_ERROR){
                return "---";
            }
            else {
                return String.valueOf(xssfRow.getStringCellValue());
            }
        }
        
        //判断后缀为xls的excel文件的数据类型
        @SuppressWarnings("deprecation")
        private static String getValue(HSSFCell hssfCell) {
            if(hssfCell==null){
                return "---";
            }
            if (hssfCell.getCellType() == hssfCell.CELL_TYPE_BOOLEAN) {
                return String.valueOf(hssfCell.getBooleanCellValue());
            } else if (hssfCell.getCellType() == hssfCell.CELL_TYPE_NUMERIC) {
                double cur=hssfCell.getNumericCellValue();
                long longVal = Math.round(cur);
                Object inputValue = null;
                if(Double.parseDouble(longVal + ".0") == cur)  
                        inputValue = longVal;  
                else  
                        inputValue = cur; 
                return String.valueOf(inputValue);
            } else if(hssfCell.getCellType() == hssfCell.CELL_TYPE_BLANK || hssfCell.getCellType() == hssfCell.CELL_TYPE_ERROR){
                return "---";
            }
            else {
                return String.valueOf(hssfCell.getStringCellValue());
            }
        }
        
      //字符串修剪  去除所有空白符号 ， 问号 ， 中文空格
        static private String Trim_str(String str){
            if(str==null)
                return null;
            return str.trim();//str.replaceAll("[\s\?]", "").replace("　", "");
        }

4、使用POI设置EXCEL文件单元格格式

     ---->批量修改指定列多行单元格的颜色

        /**
         * description:批量修改指定sheet表中某列的多行单元格格式（颜色）
         */
        public  void setXLSXColor(String url,int sheetNumber,ArrayList<Integer> rowNumbers,int colNumber) throws IOException {//XLSX 的单元格填充颜色
             //读取xlsx文件
            InputStream is = new FileInputStream(new File(url));            
            XSSFWorkbook my_workbook = new XSSFWorkbook(is);        
            XSSFCellStyle my_style = my_workbook.createCellStyle(); // Get access to XSSFCellStyle */
            my_style.setFillPattern(XSSFCellStyle.FINE_DOTS );
            my_style.setFillForegroundColor(IndexedColors.BRIGHT_GREEN.getIndex());
            //my_style.setFillBackgroundColor(IndexedColors.RED.getIndex());
            is.close();      
            XSSFSheet xssfSheet = my_workbook.getSheetAt(sheetNumber);  //拿取xlsx中的sheetNumber,设置单元格颜色
            XSSFCell cellTarge = null;
            for(int i=0;i < rowNumbers.size();i++) {
                cellTarge = xssfSheet.getRow(rowNumbers.get(i)).getCell(colNumber);
                cellTarge.setCellStyle(my_style);
            }     
            FileOutputStream out = new FileOutputStream(new File(url));
            my_workbook.write(out);
            out.close();
        }

5、参考文献

<1> https://blog.csdn.net/qq547276542/article/details/75175289

<2> https://www.oschina.net/code/snippet_12_16825