JAVA代碼實現嵌套層級列表，POI導出嵌套層級列表

要實現POI導出EXCEL形如

--A1(LV1)

----B1(LV2)

----B2(LV2)

------C1(LV3)

------C2(LV3)

----B3(LV2)

--A1(LV1)

 

一.能用到的數據字段

ID(主鍵)、PID（父科目ID）、NAME(名稱)、LEVEL（當前層級）

 

二.思路：

定義一個空的科目列表用來存放已經排好序的科目。創建一個迭代器傳入父節點查出它的所有子節點，遍歷子節點插入到科目列表的同時再次調用這個迭代器，這樣程序能夠在插入一個節點后如果發現有子節點繼續插入子節點。最后返回排好序的科目樹。

 

三.JAVA代碼

 

/**
 * 
 * <p>Description: 根據根節點獲取嵌套科目樹</p>
 * @param root 根節點，只需itemCode
 * @return 嵌套科目樹
 */
public List<Subject> getSubjectListByRoot(Subject root){
    //定義一個空的科目列表
    List<Subject> subjectTree = new ArrayList<Subject>();
    //查詢出根節點的具體信息
    root = this.subjectManager.searchSubjectByCode(root.getItemCode());
    //將根節點插入到嵌套科目樹里，因為迭代出來的科目樹是沒有根節點的
    subjectTree.add(root);
    //調用迭代器
    subjectTree = SubjectIteration(root, subjectTree);
    return subjectTree;
}

/**
 * 
 * <p>Description: 嵌套科目樹迭代器</p>
 * @param subject 父節點
 * @param subjectTree 科目樹
 * @return 嵌套科目樹
 */
public List<Subject> SubjectIteration(Subject subject, List<Subject> subjectTree) {
    //根據父節點查子節點
    List<Subject> subjects = this.subjectManager.searchListSubjectByParent(subject);
    if (subjects != null) {
        //遍歷子節點並迭代
        for (Subject subjectResult : subjects) {
            //將節點插入到嵌套科目樹里
            subjectTree.add(subjectResult);
            SubjectIteration(subjectResult,subjectTree);
        }
    }
    return subjectTree;
}

 

 

四.SQL

根據父節點查子節點的一段SQL只需比對父節點的ID和子節點的PID即可

 

五.POI導出

/**
 * 
 * <p>Description: 科目樹導出</p>
 * @param request
 * @param response
 * @return Excel文件
 * @throws Exception
 */
public ModelAndView downloadExcel(HttpServletRequest request, 
        HttpServletResponse response) throws Exception {
    //文件配置
    String fileName = new String(("科目導出文件.xls").getBytes("UTF-8"), "iso-8859-1");
    response.reset();
    response.setHeader("Content-disposition", "attachment;filename=" + fileName);
    response.setContentType("application/vnd.ms-excel;charset=utf-8");
    //創建POI-workbook文件
    XSSFWorkbook workbook = new XSSFWorkbook();
    XSSFSheet sheet = workbook.createSheet("科目樹");
    //插入抬頭
    PoiUtil.addRowSXSSF(sheet, 0, new String[] { "說明：", "level1", "level2", "level3", "level4", "level5", "level6",
            "level7", "level8" });
    //調整sheet樣式
    //紅
    CellStyle styleRed = workbook.createCellStyle();
    styleRed.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleRed.setFillForegroundColor(IndexedColors.RED.index);
    //綠
    CellStyle styleGreen = workbook.createCellStyle();
    styleGreen.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleGreen.setFillForegroundColor(IndexedColors.LIME.index);
    //灰
    CellStyle styleGrey = workbook.createCellStyle();
    styleGrey.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleGrey.setFillForegroundColor(IndexedColors.GREY_25_PERCENT.index);
    //白
    CellStyle styleWhite = workbook.createCellStyle();
    styleWhite.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleWhite.setFillForegroundColor(IndexedColors.WHITE.index);
    //金黃
    CellStyle styleGold = workbook.createCellStyle();
    styleGold.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleGold.setFillForegroundColor(IndexedColors.GOLD.index);
    //黃
    CellStyle styleYellow = workbook.createCellStyle();
    styleYellow.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleYellow.setFillForegroundColor(IndexedColors.YELLOW.index);
    //亮黃
    CellStyle styleLight = workbook.createCellStyle();
    styleLight.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleLight.setFillForegroundColor(IndexedColors.LIGHT_YELLOW.index);
    //檸檬
    CellStyle styleLemon = workbook.createCellStyle();
    styleLemon.setFillPattern(XSSFCellStyle.SOLID_FOREGROUND);
    styleLemon.setFillForegroundColor(IndexedColors.LEMON_CHIFFON.index);
    //設置抬頭顏色
    XSSFRow row = sheet.getRow(0);
    Cell cell = row.getCell(1);
    cell.setCellStyle(styleRed);
    cell = row.getCell(2);
    cell.setCellStyle(styleGreen);
    cell = row.getCell(3);
    cell.setCellStyle(styleGrey);
    cell = row.getCell(4);
    cell.setCellStyle(styleWhite);
    cell = row.getCell(5);
    cell.setCellStyle(styleGold);
    cell = row.getCell(6);
    cell.setCellStyle(styleYellow);
    cell = row.getCell(7);
    cell.setCellStyle(styleLight);
    cell = row.getCell(8);
    cell.setCellStyle(styleLemon);
    //查詢Excel用科目樹
    List<Subject> subjectTree = new ArrayList<Subject>();
    Subject root = new Subject();
    root.setItemCode("1001");
    subjectTree = getSubjectListByRoot(root);
    //插入數據
    int index = 0;
    for(Subject subject : subjectTree){
        index = index + 1;
        Row dataRow = sheet.createRow(index);
        String lv = subject.getLevel();
        if(lv.equals("1")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleRed);
        }
        else if(lv.equals("2")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleGreen);
        }
        else if(lv.equals("3")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleGrey);
        }
        else if(lv.equals("4")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleWhite);
        }
        else if(lv.equals("5")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleGold);
        }
        else if(lv.equals("6")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleYellow);
        }
        else if(lv.equals("7")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleLight);
        }
        else if(lv.equals("8")){ 
            Cell dataCell = dataRow.createCell(0);
            dataCell.setCellValue(subject.getItemName());
            dataCell.setCellStyle(styleLemon);
        }
    }
    sheet.setColumnWidth(0, 9000);
    //創建輸出流，生成文件
    OutputStream out = new BufferedOutputStream(response.getOutputStream());
    workbook.write(out);
    out.flush();
    out.close();
    return null;
}