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Kotlin如何实现MVP架构 [复制链接]

2017-8-15 10:29
liujh 阅读:2167 评论:1 赞:1
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最近MVP火的不要不要的,我也来凑盘热闹,其实MVP的文章看了好多了,但是一直还停留在概念阶段,这几天对Google Android的todoapp的代码进行了解析,然后使用Kotlin翻译了一下,算了对MVP有了一个大概的认识,那么MVP究竟是什么,网上一搜一大堆,我就把名字复述一下,MVP的全称为Model-View-Presenter,即模型-视图-协调器(主持者),最重要的功能还是解耦,代码也更容易扩展和维护,下面我们还是来看具体的例子:demo还是做一个干货的列表页:

先看目录结构,


Paste_Image.png

这里单独建了个MVP的包,base中定义了两个接口BaseViewBasePresenter

BaseView

package com.vslimit.kotlindemo.mvp.base

/**
 * Created by vslimit on 17/1/6.
 */
interface BaseView<T> {
    fun setPresenter(presenter: T)
}

BasePresenter

package com.vslimit.kotlindemo.mvp.base

/**
 * Created by vslimit on 17/1/6.
 */
interface BasePresenter {
    fun start()
}

实现Contract

GanksContract

package com.vslimit.kotlindemo.mvp.ganks

import com.vslimit.kotlindemo.model.Gank
import com.vslimit.kotlindemo.mvp.base.BasePresenter
import com.vslimit.kotlindemo.mvp.base.BaseView

/**
 * Created by vslimit on 17/1/10.
 */
interface GanksContract {

    interface View : BaseView<Presenter> {
        fun showGanks(ganks: List<Gank>)
        fun showTip(message:String)
        fun showLoading()
        fun hideLoading()
    }

    interface Presenter : BasePresenter {
        fun loadGanks()
    }

}

接口中定义了需要实现想要展示的View,而Presenter处理交互,下面我们来看具体的实现类:

GanksPresenter

package com.vslimit.kotlindemo.mvp.ganks

import com.vslimit.kotlindemo.model.Gank
import com.vslimit.kotlindemo.model.GankListResult
import com.vslimit.kotlindemo.service.RestfulService
import com.vslimit.kotlindemo.service.ServiceFactory
import rx.Subscriber
import rx.android.schedulers.AndroidSchedulers
import rx.schedulers.Schedulers

/**
 * Created by vslimit on 17/1/11.
 */
class GanksPresenter : GanksContract.Presenter {

    var mGanksView: GanksContract.View? = null

    constructor(ganksView: GanksContract.View) {
        mGanksView = checkNotNull(ganksView)
        mGanksView!!.setPresenter(this)
    }

    override fun loadGanks() {
        mGanksView!!.showLoading()
        val service = ServiceFactory.createRetrofitService(RestfulService::class.java, RestfulService.GANK_SERVICE_ENDPOINT)
        service.loadGanks().subscribeOn(Schedulers.newThread()).observeOn(AndroidSchedulers.mainThread()).subscribe(object : Subscriber<GankListResult>() {
            override fun onCompleted() {
                mGanksView!!.hideLoading()
            }

            override fun onError(e: Throwable) {
                mGanksView!!.showTip(e.toString())
            }

            override fun onNext(result: GankListResult) {
                processGanks(result.results)
            }
        })
    }

    override fun start() {
        loadGanks()
    }

    fun processGanks(ganks: List<Gank>) {
        mGanksView!!.showGanks(ganks)
    }


}

这里只实现了一个交互,即从服务端获取ganks数据,获取数据的实现请参考之前的文章传送门,既然数据OK了,那我们就来看看View是如何展示的:

GanksFragment

package com.vslimit.kotlindemo.mvp.ganks

import android.os.Bundle
import android.support.v7.widget.LinearLayoutManager
import android.view.View
import com.vslimit.kotlindemo.R
import com.vslimit.kotlindemo.adapter.BaseAdapter
import com.vslimit.kotlindemo.extensions.loading
import com.vslimit.kotlindemo.fragment.BaseFragment
import com.vslimit.kotlindemo.model.Gank
import com.vslimit.kotlindemo.util.Const
import kotlinx.android.synthetic.main.fragment_ganks.*
import kotlinx.android.synthetic.main.item_list_gank.view.*
import org.jetbrains.anko.info
import org.jetbrains.anko.onClick
import org.jetbrains.anko.support.v4.act
import org.jetbrains.anko.support.v4.toast

/**
 * Created by vslimit on 17/1/10.
 */
class GanksFragment : BaseFragment(), GanksContract.View {
    override val layoutResourceId: Int = R.layout.fragment_ganks

    var mPresenter: GanksContract.Presenter? = null
    var adapter: BaseAdapter<Gank>? = null

    companion object {
        fun getInstance(): GanksFragment {
            return GanksFragment()
        }
    }

    override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val layoutManager: LinearLayoutManager = LinearLayoutManager(act)
        gankListRv.layoutManager = layoutManager
        adapter = BaseAdapter(R.layout.item_list_gank, arrayListOf()) { view: View, item: Gank ->
            view.item_gank_title.text = item.desc
            view.item_gank_who.text = item.who
            view.item_gank_date.text = item.publishedAt
            view.onClick {
                showTip("onclick")
            }

        }
        gankListRv.adapter = adapter

    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
    }

    override fun hideLoading() {
        loading(Const.HIDE)
    }

    override fun showLoading() {
        loading(Const.SHOW)

    }

    override fun showTip(message: String) {
        toast(message)
    }

    override fun setPresenter(presenter: GanksContract.Presenter) {
        mPresenter = checkNotNull(presenter)
        info("demo")
    }

    override fun onResume() {
        super.onResume()
        mPresenter?.start()
    }

    override fun showGanks(ganks: List<Gank>) {
        adapter!!.items = ganks
        adapter!!.notifyDataSetChanged()
    }

}

在这个fragment同样使用了之前文章封装的通用RecycleView.Adapter,有兴趣的朋友可以回头看看之前的文章传送门,最后我们来看看Activity都实现了什么:

GanksActivity

package com.vslimit.kotlindemo.mvp.ganks

import android.os.Bundle
import android.support.design.widget.NavigationView
import android.support.v4.view.GravityCompat
import android.support.v4.widget.DrawerLayout
import android.view.MenuItem
import com.vslimit.kotlindemo.R
import com.vslimit.kotlindemo.activity.BaseActivity
import com.vslimit.kotlindemo.ui.DrawerLayoutManager
import org.jetbrains.anko.find

/**
 * Created by vslimit on 17/1/10.
 */
class GanksActivity(override val layoutResourceId: Int = R.layout.activity_tasks) :BaseActivity(),DrawerLayoutManager{

    override val drawerLayout by lazy { find<DrawerLayout>(R.id.drawer_layout) }
    val navigationView by lazy { find<NavigationView>(R.id.nav_view) }
    var mGanksPresenter: GanksPresenter? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setupDrawerContent(navigationView, R.id.drawLayoutTask)

        val ganksFragment = GanksFragment.getInstance()
        if (savedInstanceState == null) {
            initFragment(ganksFragment)
        }
        mGanksPresenter = GanksPresenter(ganksFragment)

    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        when (item.itemId) {
            android.R.id.home -> {
                drawerLayout.openDrawer(GravityCompat.START)
                return true
            }
        }
        return super.onOptionsItemSelected(item)
    }

}

至此,基于Kotlin的MVP已经实现,从代码中不难看出,modelview实现了解耦,那么问题来了,是不是MVP适用于所有场景,就我个人的感觉,如果页面UI设计复杂,交互多,那应该使用MVP,这样,能达到解耦的目的和效果,并且便于以后的维护和扩展,但是,如果只是单一的交互,比如登录或者像本文的只是个列表展示或详情,那就直接用ActivityFragment即可,毕竟杀鸡用牛刀确实有点小题大做的感觉;至于说项目中究竟用MVC还是MVP要看具体场景以及个人喜好。

哦,对了,效果图(懒得截图,就使用之前的了,不过点击按钮在侧滑菜单中,列表效果是一样的):




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权小阳 2017-8-16 15:17
博主 可以尝试参加安卓巴士第三期博文大赛哦~  http://www.apkbus.com/thread-282214-1-1.html
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