确实需要注意加上引号，谢谢各位提醒：

this.setUsername(this.getInitParameter("username"));

this.setPassword(this.getInitParameter("password"));

public void init() throws ServletException {

super.init();//需要加上这条语句就好啦

this.setUsername(this.getInitParameter("username"));

this.setPassword(this.getInitParameter("password"));

}

加了啊

public void init() throws ServletException {

this.setUsername(this.getInitParameter("username"));

this.setPassword(this.getInitParameter("password"));

是不是username和password没有加双引号啊

你是不是同时用了config的初始化？