设计一个简单的图形化界面计算器程序，实现两个实数的四则运算。创建2个文本字段，用于输入操作数；创建1个不可编辑的文本字段，用于输出运算结果；创建4个按钮，用于输入运算符。-Graphical interface to design a simple calculator program, the four operations of the two real numbers. Create two text fields for input operands　create a non-editable text field, used to output the result of the operation　create four buttons for input operator.