十分钟学会kotlin实现Android MVP模式开发

谷歌宣布,将Kotlin语言作为安卓开发的一级编程语言
Google I/O 大会全程视频直播

为什么要学习Kotlin?因为它能使Android的开发更简洁、高效及安全,更因为谷歌的推崇!

不说废话,直入主题。很久之前在看mvp模式的时候,看多很多小例子,这里用kotlin来简单实现一下,完全是入门级的,对于刚刚了解kotlin来开发Android的同学,是个不错的例子。

完整案例和使用Dagger2、Retrofit、RxJava、Kotlin实现MVP的源码欢迎Github查看:
kotlin简单实现MVP之android-mvp源码
Kotlin结合Dagger2等开源项目实现MVP之android-mvp-kotlin源码

案例主要功能是:用户输入用户id、姓名、年龄等信息进行保存,然后通过用户id读取保存的信息。案例很简单,但是涵盖了mvp的各个要素。

MVP: Presenter与Model、View都是通过接口来进行交互的,从而来降低耦合

1.首先,创建一个数据类:
(关于kotlin知识点:1.怎么创建数据类,2.类构造方法)

/**
 * 创建一个数据类
 *
 * Kotlin知识点(data class):http://kotlinlang.org/docs/reference/data-classes.html#data-classes
 *
 * Created by wangdongdong on 17-5-23.
 */
data class User(val userName: String, val age: Int)

2.创建View接口:
(关于kotlin知识点:1.怎么创建一个接口,2.接口方法写法,3.返回值类型,4.方法的参数)

interface IUserView {

    fun getID(): Int
    fun getUsername(): String
    fun getAge(): Int
    fun setUsername(username: String)
    fun setAge(age: Int)
    fun onSaveSuccess()
}

3.创建Model接口

interface IUserModel {
    fun setId(id: Int)
    fun setUsername(username: String)
    fun setAge(age: Int)
    fun save()
    fun load(id: Int): User
}

4.创建Model实现类:
(关于kotlin知识点:1.实现接口的类,2.方法覆写)

class UserModel: IUserModel {

    private var mId: Int = 0
    private var mUsername: String = ""
    private var mAge: Int = 0
    private val mUserArray = SparseArray()

    override fun setId(id: Int) {
        mId = id
    }

    override fun setUsername(username: String) {
        mUsername = username
    }

    override fun setAge(age: Int) {
        mAge = age
    }

    override fun save() {
        mUserArray.append(mId, User(mUsername, mAge))
    }

    override fun load(id: Int): User {
        mId = id
        return mUserArray.get(mId, User("not found", 0))
    }
}

5.创建Presenter接口:

interface IUserPresenter {
    fun saveUser(id: Int, username: String, age: Int)
    fun loadUser(id: Int)
}

6.创建Presenter实现类:

class UserPresenter(val view: IUserView): IUserPresenter {

    private val mUserModel: UserModel = UserModel()

    override fun saveUser(id: Int, username: String, age: Int) {
        Log.d("test_log", "saveUser : $id,$username,$age")
        mUserModel.setId(id)
        mUserModel.setUsername(username)
        mUserModel.setAge(age)
        mUserModel.save()
        view.onSaveSuccess()
    }

    override fun loadUser(id: Int) {
        Log.d("test_log", "loadUser : $id")
        val user = mUserModel.load(id)
        view.setUsername(user.userName)
        view.setAge(user.age)
    }
}

7.创建Activity:

class MainActivity : AppCompatActivity(), IUserView, View.OnClickListener {

    private var mUserPresenter: UserPresenter? = null

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

        mUserPresenter = UserPresenter(this)
        saveButton.setOnClickListener(this)
        loadButton.setOnClickListener(this)
    }

    override fun onClick(v: View) {
        when(v.id) {
            R.id.saveButton -> mUserPresenter?.saveUser(getID(), getUsername(), getAge())
            R.id.loadButton -> mUserPresenter?.loadUser(getID())
        }
    }

    override fun onSaveSuccess() {
        edt_id.setText("")
        edt_username.setText("")
        edt_age.setText("")
        Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show()
    }

    override fun getID(): Int {
        val id = edt_id.text.toString().trim()
        if (id.isNotEmpty())
            return id.toInt()
        else
            return 0
    }

    override fun getUsername(): String = edt_username.text.toString()

    override fun getAge(): Int {
        val age = edt_age.text.toString().trim()
        if (age.isNotEmpty())
            return age.toInt()
        else
            return 0
    }

    override fun setUsername(username: String) {
        Log.d("test_log", "setUsername:$username")
        edt_username.text = toEditable(username)
    }

    override fun setAge(age: Int) {
        Log.d("test_log", "setUsername:$age")
        edt_age.text = toEditable(age.toString())
    }
}

结构很简洁,代码也很简单,相信看完代码后,大家对kotlin的基本使用和mvp模式都能有所了解了!

这里写图片描述

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