8.8.2为每个菜单项添加响应事件

// --设置每个菜单点击后出现的窗口和窗口显示的位置--
public void actionPerformed(ActionEvent e) {
         //“用户登录”菜单的响应函数
if (e.getActionCommand() == "用户登录") {
              //创建用户登录窗口
UserLogin userLoginFrame = new UserLogin(this);
Dimension frameSize = userLoginFrame.getPreferredSize();
Dimension mainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的位置和大小
userLoginFrame.setLocation((mainFrameSize.width - frameSize.width)
/ 2 + loc.x, (mainFrameSize.height - frameSize.height) / 2
+ loc.y);
userLoginFrame.pack();
userLoginFrame.show();
} else if (e.getActionCommand() == "添加用户") {
              //“添加用户”菜单的响应函数
UserAdd UserAddFrame = new UserAdd();
Dimension FrameSize = UserAddFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
UserAddFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
UserAddFrame.pack();
UserAddFrame.show();
} else if (e.getActionCommand() == "修改用户") {
              //“修改用户”菜单的响应函数
UserModify UserModifyFrame = new UserModify();
Dimension FrameSize = UserModifyFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
UserModifyFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
UserModifyFrame.pack();
UserModifyFrame.show();
} else if (e.getActionCommand() == "删除用户") {
              //初始化“删除用户“窗口
UserDelete UserDeleteFrame = new UserDelete();
Dimension FrameSize = UserDeleteFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
UserDeleteFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
UserDeleteFrame.pack();
              //显示窗口
UserDeleteFrame.show();
} else if (e.getActionCommand() == "添加书籍") {
              //“添加书籍”窗口
BookAdd BookAddFrame = new BookAdd();
Dimension FrameSize = BookAddFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
             //设置窗口的大小和位置
BookAddFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
BookAddFrame.pack();
              //显示添加书籍窗口
BookAddFrame.show();
} else if (e.getActionCommand() == "修改书籍") {
              //初始化“书籍修改”窗口
BookModify BookModifyFrame = new BookModify();
Dimension FrameSize = BookModifyFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
BookModifyFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
BookModifyFrame.pack();
              //显示“修改书籍”窗口
BookModifyFrame.show();
} else if (e.getActionCommand() == "删除书籍") {
              //初始化“删除书籍”窗口
BookDelete BookDeleteFrame = new BookDelete();
Dimension FrameSize = BookDeleteFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
BookDeleteFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
BookDeleteFrame.pack();
              //显示窗口
BookDeleteFrame.show();
} else if (e.getActionCommand() == "书籍出借") {
              //初始化“书籍出借”窗口
BorrowBook BorrowBookFrame = new BorrowBook();
Dimension FrameSize = BorrowBookFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
BorrowBookFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
BorrowBookFrame.pack();
              //显示窗口
BorrowBookFrame.show();
} else if (e.getActionCommand() == "出借信息修改") {
              //初始化“出借信息修改”窗口
BorrowInfo BorrowInfoFrame = new BorrowInfo();
Dimension FrameSize = BorrowInfoFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
BorrowInfoFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
BorrowInfoFrame.pack();
              //显示窗口
BorrowInfoFrame.show();
} else if (e.getActionCommand() == "书籍还入") {
              //初始化“书籍还入”窗口
ReturnBook returnBookFrame = new ReturnBook();
Dimension FrameSize = returnBookFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
returnBookFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
returnBookFrame.pack();
              //显示窗口
returnBookFrame.show();
} else if (e.getActionCommand() == "书籍还入信息修改") {
              //初始化“书籍还入信息修改”窗口
ReturnInfo returnInfoFrame = new ReturnInfo();
Dimension FrameSize = returnInfoFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
returnInfoFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
returnInfoFrame.pack();
              //显示窗口
returnInfoFrame.show();
} else if (e.getActionCommand() == "书籍列表") {
              //初始化“书籍列表”窗口
BookList BookListFrame = new BookList();
Dimension FrameSize = BookListFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
BookListFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
BookListFrame.pack();
              //显示窗口
BookListFrame.show();
} else if (e.getActionCommand() == "借阅情况表") {
              //初始化“借阅情况表”窗口
BorrowBookList BorrowBookListFrame = new BorrowBookList();
Dimension FrameSize = BorrowBookListFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
BorrowBookListFrame.setLocation(
(MainFrameSize.width - FrameSize.width) / 2 + loc.x,
(MainFrameSize.height - FrameSize.height) / 2 + loc.y);
BorrowBookListFrame.pack();
              //显示窗口
BorrowBookListFrame.show();
} else if (e.getActionCommand() == "用户列表") {
              //显示“用户列表”窗口
UserList UserListFrame = new UserList();
Dimension FrameSize = UserListFrame.getPreferredSize();
Dimension MainFrameSize = getSize();
Point loc = getLocation();
              //设置窗口的大小和位置
UserListFrame.setLocation((MainFrameSize.width - FrameSize.width)
/ 2 + loc.x, (MainFrameSize.height - FrameSize.height) / 2
+ loc.y);
UserListFrame.pack();
              //显示窗口
UserListFrame.show();
} else if (e.getActionCommand() == "退出") {
this.dispose();
              //系统退出
System.exit(0);
}
}