java基础

错误: 找不到或无法加载主类

参考：https://blog.csdn.net/qq_37958845/article/details/82420976

  1. # CLASSPATH环境变量配置
  2. .;%JAVA_HOME%\lib;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar

错误: 编码GBK的不可映射字符

  1. # 编译时指定编码
  2. javac -encoding UTF-8 test.java
  3. java test

POI操作word、excel…

EasyPoi导入Excel

  • 标题包含行、列合并单元格，具体列名重复，保存格式为List<Map> ，重复列名数据丢失

1.导入Excel标题如图
image.png

EasyPoi4.2.0读取列名方法是，ExcelImportService.getTitleMap(…)

2.读取结果为：
…
高校教师资格证书发证单位（全称）
获奖日期（年月）
…
专业技术职务（最高）等级
名称（全称）
发证单位（全称）——————该标题由于Map的key不能重复，未读取

3.于是，修改ExcelImportService.getTitleMap(…)获取列名方式

读取结果为：**
高校教师资格证书发证单位（全称）
专业技术职务（最高）发证单位（全称）

  1.     //修改ExcelImportService.getTitleMap(...)
  2.     //368行    
  3.     String value = getJoinCellValue(sheet, cell.getRowIndex(), cell.getColumnIndex(), 2);
  5.     /**
  6.      * 判断单元格是否是合并的单元格
  7.      * @param sheet
  8.      * @param row 单元格所在行
  9.      * @param column 单元格所在列
  10.      * @param type 合并：0，行合并：1，列合并：2
  11.      * @return
  12.      * @author chaijin
  13.      * @datetime 2020-08-26 15:29:00
  14.      */
  15.     public JoinCellInfo isJoinCell(Sheet sheet, int row, int column, int type) {
  16.         int sheetMergeCount = sheet.getNumMergedRegions();
  17.         for (int i = 0; i < sheetMergeCount; i++) {
  18.             CellRangeAddress range = sheet.getMergedRegion(i);
  19.             int firstRow = range.getFirstRow();
  20.             int lastRow = range.getLastRow();
  21.             int firstColumn = range.getFirstColumn();
  22.             int lastColumn = range.getLastColumn();
  24.             if (type == 1 && lastRow == firstRow) {
  25.                 continue;
  26.             }
  27.             if (type == 2 && lastColumn == firstColumn) {
  28.                 continue;
  29.             }
  31.             if(row >= firstRow && row <= lastRow){
  32.                 if(column >= firstColumn && column <= lastColumn){
  33.                     return new JoinCellInfo(true, firstRow, lastRow, firstColumn, lastColumn);
  34.                 }
  35.             }
  36.         }
  37.         return new JoinCellInfo(false, 0, 0, 0, 0);
  38.     }
  40.     /**
  41.      * 获取单元格的值
  42.      * @param sheet
  43.      * @param row 单元格所在行
  44.      * @param column 单元格所在列
  45.      * @param type 合并：0，行合并：1，列合并：2
  46.      * @return
  47.      * @author chaijin
  48.      * @datetime 2020-08-26 15:29:00
  49.      */
  50.     public String getJoinCellValue(Sheet sheet, int row, int column, int type) {
  51.         JoinCellInfo joinCell = isJoinCell(sheet, row, column, type);
  52.         if (joinCell.isJoinCell) {
  53.             row = joinCell.getFirstRow();
  54.             column = joinCell.getFirstColumn();
  55.         }
  56.         return sheet.getRow(row).getCell(column).getStringCellValue();
  57.     }
  59.     /*
  60.      合并单元格信息类
  61.      */
  62.     class JoinCellInfo{
  63.         private boolean isJoinCell; //是否是合并单元格
  64.         private int firstRow;       //合并开始行
  65.         private int lastRow;        //合并结束行
  66.         private int firstColumn;    //合并开始列
  67.         private int lastColumn;     //合并结束列
  69.         public JoinCellInfo(boolean isJoinCell, int firstRow, int lastRow, int firstColumn, int lastColumn) {
  70.             this.isJoinCell = isJoinCell;
  71.             this.firstRow = firstRow;
  72.             this.lastRow = lastRow;
  73.             this.firstColumn = firstColumn;
  74.             this.lastColumn = lastColumn;
  75.         }
  77.         public boolean isJoinCell() {
  78.             return isJoinCell;
  79.         }
  81.         public void setJoinCell(boolean joinCell) {
  82.             isJoinCell = joinCell;
  83.         }
  85.         public int getFirstRow() {
  86.             return firstRow;
  87.         }
  89.         public void setFirstRow(int firstRow) {
  90.             this.firstRow = firstRow;
  91.         }
  93.         public int getLastRow() {
  94.             return lastRow;
  95.         }
  97.         public void setLastRow(int lastRow) {
  98.             this.lastRow = lastRow;
  99.         }
  101.         public int getFirstColumn() {
  102.             return firstColumn;
  103.         }
  105.         public void setFirstColumn(int firstColumn) {
  106.             this.firstColumn = firstColumn;
  107.         }
  109.         public int getLastColumn() {
  110.             return lastColumn;
  111.         }
  113.         public void setLastColumn(int lastColumn) {
  114.             this.lastColumn = lastColumn;
  115.         }
  116.     }