import 
import jxl.Cell;
import jxl.CellType;
import jxl.DateCell;
import jxl.NumberCell;
import jxl.Sheet;
import jxl.Workbook;
public class Excel{
public static void main(String args[]) {
   try {
    Workbook workbook = null;
    try {
     workbook = Workbook.getWorkbook(new File("d://test.xls"));
    } catch (Exception e) {
     throw new Exception("file to import not found!");
    }
    Sheet sheet = workbook.getSheet(0);
    Cell cell = null;
    int columnCount = 3;
    int rowCount = sheet.getRows();
    for (int i = 0; i < rowCount; i++) {
     for (int j = 0; j < columnCount; j++) {
      // 注意,这里的两个参数,第一个是表示列的,第二才表示行
      cell = sheet.getCell(j, i);
      // 要根据单元格的类型分别做处理,否则格式化过的内容可能会不正确
      if (cell.getType() == CellType.NUMBER) {
       System.out.print(((NumberCell) cell).getValue());
      } else if (cell.getType() == CellType.DATE) {
       System.out.print(((DateCell) cell).getDate());
      } else {
       System.out.print(cell.getContents());
      }
      // System.out.print(cell.getContents());
      System.out.print("\t");
     }
     System.out.print("\n");
    }
    // 关闭它,否则会有内存泄露
    workbook.close();
   } catch (Exception e) {
   }
}
}
编译通过后,执行时提示一下错误:请问错在哪里?
D:\j>javac Excel.java
D:\j>java Excel
Exception in thread "main" java.lang.NoClassDefFoundError: jxl/Workbook
        at Excel.main(Excel.java:16)
Caused by: java.lang.ClassNotFoundException: jxl.Workbook
        at (Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at (Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)
        ... 1 more