這一章是列表ViewModel的具體使用小結(jié)。

Model

比如我們要請(qǐng)求一個(gè)門(mén)票列表，地址為http://www.bigkoo.com/api/list/ticket
參數(shù)page和pageSize分別代表當(dāng)前頁(yè)和一頁(yè)多少個(gè)item，返回格式

{"code":0,"msg":"獲取詳情成功","content":[{"productId":"1200001","spotName":"門(mén)票名稱1"},{"productId":"1200002","spotName":"門(mén)票名稱2"}]}

那么則建立一個(gè)叫Ticket的Model，屬性有productId，spotName

public class Ticket {
    /**
     * productId : 923010086
     * spotName : 藍(lán)水河漂流
     */

    private String productId;
    private String spotName;

    public String getProductId() {
        return productId;
    }

    public void setProductId(String productId) {
        this.productId = productId;
    }

    public String getSpotName() {
        return spotName;
    }

    public void setSpotName(String spotName) {
        this.spotName = spotName;
    }

HttpService里面也加入對(duì)應(yīng)接口

@GET("api/list/ticket")Call<HttpResult<List<Ticket>>> getTicketList(@Query("page") int page, @Query("pageSize") int pageSize);

建立列表ViewModel

TicketListViewModel 就是具體實(shí)現(xiàn)的ViewModel，通過(guò)onLoadListHttpRequest指定請(qǐng)求的接口和返回的類(lèi)型Ticket

public class TicketListViewModel extends BaseRefreshRecyclerViewModel{

    public TicketListViewModel(){
        super(R.layout.item_ticketlist);
        onListRefresh();
    }
    @Override
    public Call<HttpResult<List<Ticket>>> onLoadListHttpRequest() {
        return HttpServiceGenerator.createService().getTicketList(getPage(),getPageSize());
    }

    @Override
    public void onItemClick(View v, int position, View itemView, Object item) {
    }
}

這個(gè)列表item對(duì)應(yīng)的 item_ticketlist.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>

        <variable
            name="viewModel"
            type="com.bigkoo.mvvmframeworkdemo.model.Ticket" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
        <TextView
            android:text="@{viewModel.spotName}"
            android:layout_width="match_parent"
            android:layout_height="50dp" />

    </LinearLayout>
</layout>

這個(gè)列表Activity對(duì)應(yīng)的xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:fitsSystemWindows="true">

    <data>

        <variable
            name="viewModel"
            type="com.bigkoo.mvvmframeworkdemo.viewmodel.TicketListViewModel" />

    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <include layout="@layout/include_recyclerview_refresh"
            app:viewModel="@{viewModel}"/>

    </FrameLayout>

</layout>

然后就是Databinding綁定xml到Activity的知識(shí)了，具體請(qǐng)看源碼例子。

列表的幾個(gè)狀態(tài)可以拓展上面Activity的xml，改為

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:fitsSystemWindows="true">

    <data>

        <variable
            name="viewModel"
            type="com.bigkoo.mvvmframeworkdemo.viewmodel.TicketListViewModel" />

    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <include layout="@layout/include_recyclerview_refresh"
            app:viewModel="@{viewModel}"/>

        <include layout="@layout/include_status_error"
            app:viewModel="@{viewModel}"/>

        <include layout="@layout/include_status_networkerror"
            app:viewModel="@{viewModel}"/>
    </FrameLayout>

</layout>

這里舉一反三，服務(wù)器異常錯(cuò)誤對(duì)應(yīng)的xml，做成include供其他頁(yè)面公用，其他狀態(tài)的xml類(lèi)似。還記得嗎？ViewModel中的callback的時(shí)候已經(jīng)封裝了這些狀態(tài)的改變，所以現(xiàn)在我們不用在ViewModel中加任何代碼就能實(shí)現(xiàn)這些狀態(tài)界面的顯示和隱藏控制。

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

        <variable
            name="viewModel"
            type="com.bigkoo.mvvmframework.viewmodel.BaseViewModel" />
        <variable
            name="emptyTips"
            type="String" />

        <import type="android.view.View" />

    </data>

    <LinearLayout
        android:clickable="true"
        app:setReload="@{viewModel}"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/white"
        android:gravity="center_horizontal"
        android:orientation="vertical"
        android:visibility="@{viewModel.statusError ? View.VISIBLE : View.GONE}">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            android:textSize="20dp"
            android:text="服務(wù)器異常" />

    </LinearLayout>

</layout>

一個(gè)帶下拉刷新，滑動(dòng)到最后一行加載更多，不同狀態(tài)顯示不同界面的列表就這么輕松的實(shí)現(xiàn)了。

Github

MVVMFramework