[移动开发]Android 状态模式的运用

状态模式运用

流程图

代码实现

定义登陆状态接口

interface IUserState {
    fun like(context: Context)
    fun comment(context: Context)
}

实现登陆登出状态

class LoginedState : IUserState {
    override fun like(context: Context) {
        Toast.makeText(context, "点赞", Toast.LENGTH_SHORT).show()
    }

    override fun comment(context: Context) {
        Toast.makeText(context, "评论", Toast.LENGTH_SHORT).show()
    }
}

class LogoutState : IUserState {
    override fun like(context: Context) {
        toLogin(context)
    }

    override fun comment(context: Context) {
        toLogin(context)
    }

    private fun toLogin(context: Context) {
        context.startActivity(Intent(context, LoginActivity::class.java))
    }
}

定义管理登陆状态类

object LoginContext {
    public var userState: IUserState = LogoutState()

    fun like(context: Context) {
        userState.like(context)
    }

    fun comment(context: Context) {
        userState.comment(context)
    }
}

定义主界面

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        findViewById<Button>(R.id.like).setOnClickListener {
            LoginContext.like(this)
        }
        findViewById<Button>(R.id.comment).setOnClickListener {
            LoginContext.comment(this)
        }
        findViewById<Button>(R.id.to_login).setOnClickListener {
            startActivity(Intent(this, LoginActivity::class.java))
        }
        findViewById<Button>(R.id.logout).setOnClickListener {
            LoginContext.userState = LogoutState()
        }
    }
}

定义登陆界面

class LoginActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_login)
        findViewById<Button>(R.id.login).setOnClickListener {
            LoginContext.userState = LoginedState()
            finish()
        }
    }
}

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