要求点击登录时，弹出登陆成功，保存成功，同时使用SharedPreferences保存用户名和密码。
下次启动app时，读取保存的用户名密码，直接显示在textview上。
顺便剧透一下明天专业外语测试题：
汉译英：
编译 字节码 分支 脚本 客户端 浏览器
英译汉:
JSP BIOS HTTP platform device (java vitrul machine)
句子翻译：More recently, the Java programming language, a language used in object-oriented
programming, has introduced the possibility of compiling output (called bytecode) that can run on
any computer system platform for which a Java virtual machine or bytecode interpreter is
provided to convert the bjrtecode into instructions that can be executed by the actual hardware
processor
