在一个JFrame的窗体上放置一个文本区,点击“File”下拉菜单中的“Open”项或工具条中的“打开”按钮,弹出打开对话框，选择一个文本文件后，在文本区中显示其内容。单击“Exit”按钮或工具条中的“退出”按钮则关闭整个程序-a JFrame in the Form place a text, Click on the "File" drop-down menu on the "Open" or tools of the "open" button, pop open the dialog box, select a text file, in the text area reveal their contents. Click the "Exit" button or the tools of the "withdrawal" button to turn off the whole process