包poi.org.apache.poi.hssf.usermodel不存在

Question

编译代码时，我遇到了这些错误：

CreateWorkBook.java:3: error: package poi.org.apache.poi.hssf.usermodel does not exist
import poi.org.apache.poi.hssf.usermodel.HSSFSheet;
                                        ^
CreateWorkBook.java:4: error: package poi.org.apache.poi.hssf.usermodel does not exist
import poi.org.apache.poi.hssf.usermodel.HSSFWorkbook;
                                        ^
CreateWorkBook.java:13: error: cannot find symbol
                HSSFWorkbook workbook = new HSSFWorkbook(file);
                ^
  symbol:   class HSSFWorkbook
  location: class CreateWorkBook
CreateWorkBook.java:13: error: cannot find symbol
                HSSFWorkbook workbook = new HSSFWorkbook(file);
                                            ^
  symbol:   class HSSFWorkbook
  location: class CreateWorkBook
CreateWorkBook.java:16: error: cannot find symbol
                HSSFSheet sheet = workbook.getSheetAt(0);
                ^
  symbol:   class HSSFSheet
  location: class CreateWorkBook
CreateWorkBook.java:19: error: cannot find symbol
                Iterator<Row> rowIterator = sheet.iterator();
                ^
  symbol:   class Iterator
  location: class CreateWorkBook
CreateWorkBook.java:19: error: cannot find symbol
                Iterator<Row> rowIterator = sheet.iterator();
                         ^
  symbol:   class Row
  location: class CreateWorkBook
CreateWorkBook.java:22: error: cannot find symbol
                Iterator<Cell> cellIterator = row.cellIterator();
                ^
  symbol:   class Iterator
  location: class CreateWorkBook
CreateWorkBook.java:22: error: cannot find symbol
                Iterator<Cell> cellIterator = row.cellIterator();
                         ^
  symbol:   class Cell
  location: class CreateWorkBook
CreateWorkBook.java:22: error: cannot find symbol
                Iterator<Cell> cellIterator = row.cellIterator();
                                              ^
  symbol:   variable row
  location: class CreateWorkBook
10 errors

我该怎么办？我已经在几个地方看过了，但我没有设法纠正这些错误。

我使用：javac CreateWorkBook.java编译我的代码 并使用以下命令运行代码：java CreateWorkBook

（对不起，如果我的英语不好。）