android动态添加布局（基于mvvm和databinding）

android 常常需要动态添加布局例如：


需要后台返回的天数个数来动态添加布局，有一下几种写法：

方式1。 基于recycleView
recyclerView使用了基于mvvm和databinding的框架github地址

xml布局，通过后台返回天数的数量daySize显示多少个布局

<?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>
        <import type="me.tatarka.bindingcollectionadapter2.LayoutManagers"/>
        <variable
            name="viewCtrl"
            type="com.example.example.dynamicAddLayout.DynamicViewCtrl"/>
    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >
        <LinearLayout
            android:id="@+id/layout"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:layout_gravity="center_horizontal">
        </LinearLayout>
       <android.support.v7.widget.RecyclerView
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_gravity="center_horizontal"
           android:gravity="center_horizontal"
           app:itemBinding="@{viewCtrl.viewModel.itemBinding}"
           app:items="@{viewCtrl.viewModel.items}"
           app:layoutManager="@{LayoutManagers.grid(viewCtrl.daySize)}">

       </android.support.v7.widget.RecyclerView>
    </LinearLayout>
</layout>

对于recyclew的使用进行了一定的封装，方便重用

public class BaseRecycleViewCtrl {
    public ObservableField<BaseRecyclerViewVM> viewModel =new ObservableField<>();

}

public abstract class BaseRecyclerViewVM<T> extends BaseObservable{
    /** 数据源 */
    public final ObservableList<T> items = new ObservableArrayList<>();
    public interface OnItemClickListener{
        void onItemClickListener(String dayStr);
    }
    OnItemClickListener listener;
    //绑定布局页面
    protected  abstract void setItemBinding(ItemBinding itemBinding, int position, T item);

    public OnItemBind<T> itemBinding =new OnItemBind<T>() {
        @Override
        public void onItemBind(ItemBinding itemBinding, int position, T item) {
            setItemBinding(itemBinding,position,item);
        }
    };

    public OnItemClickListener getListener() {
        return listener;
    }

    public void setListener(OnItemClickListener listener) {
        this.listener = listener;
    }
}

控制类viewCtrl

public class DynamicViewCtrl extends BaseRecycleViewCtrl{
    public ObservableInt daySize =new ObservableInt(3);
    public DynamicViewCtrl(final List<String> dayList){
        //dayList是后台返回的天数列表,最多显示3个（后台有时也不靠谱，自己限制一下）
        if(dayList.size()>=3){
            daySize.set(3);
        }else{
            daySize.set(dayList.size());
        }
        //绑定布局和监听，由于没有itemClick需要自己在绑定一个（自己想要添加的话可以重写这个框架）
        viewModel.set(new BaseRecyclerViewVM<DynamicItemVM>() {
            @Override
            protected void setItemBinding(ItemBinding itemBinding, int position, DynamicItemVM item) {
                itemBinding.set(BR.viewCtrl, R.layout.add_item).bindExtra(BR.listener,getListener());
            }
        });
        //设置监听，这个监听是自己设置的，对每一项都设置了点击在xml中
        viewModel.get().setListener(new BaseRecyclerViewVM.OnItemClickListener() {
            @Override
            public void onItemClickListener(String dayStr) {
                //单个选择改变背景，其他恢复原样
                for(int i=0;i< viewModel.get().items.size();i++){
                    DynamicItemVM dynamicItemVM = (DynamicItemVM) viewModel.get().items.get(i);
                    if(dayStr!=null){
                        //如果选择的天数和点击传入的天数相等
                        if(dayStr.equals(dynamicItemVM.getDayStr())){
                            //设置已选择
                            dynamicItemVM.setSelectBackground(true);
                        }else{
                            dynamicItemVM.setSelectBackground(false);
                        }
                    }
                }
            }
        });
        //设置数据源
        viewModel.get().items.clear();
        for(int i=0;i<(dayList.size()>=3?3:dayList.size());i++){
            DynamicItemVM vm =new DynamicItemVM();
            vm.setDayStr(dayList.get(i));
            if(i==0){
                vm.setSelectBackground(true);
            }else{
                vm.setSelectBackground(false);
            }
            viewModel.get().items.add(vm);
        }

    }
}

动态添加的子布局文件

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="viewCtrl"
            type="com.example.example.dynamicAddLayout.DynamicItemVM"/>
        <variable
            name="listener"
            type="com.example.example.common.BaseRecyclerViewVM.OnItemClickListener"/>
    </data>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:id="@+id/text"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:background="@{viewCtrl.selectBackground?@drawable/day_button:@drawable/day_button_line}"
            android:text="@{viewCtrl.dayStr}"
            android:onClick="@{()->listener.onItemClickListener(viewCtrl.dayStr)}"
            android:textColor="@color/colorPrimary"
            android:gravity="center"/>
    </LinearLayout>

数据model

public class DynamicItemVM extends BaseObservable{
    private String               dayStr;
    private boolean              selectBackground;
    @Bindable
    public String getDayStr() {
        return dayStr;
    }

    public void setDayStr(String dayStr) {
        this.dayStr = dayStr;
        notifyPropertyChanged(BR.dayStr);
    }
    @Bindable
    public boolean isSelectBackground() {
        return selectBackground;
    }

    public void setSelectBackground(boolean selectBackground) {
        this.selectBackground = selectBackground;
        notifyPropertyChanged(BR.selectBackground);
    }
}

方式2。直接添加布局

 ObservableArrayList<AddItemBinding> items=new ObservableArrayList<>();
  //设置布局
  LinearLayout linearLayout=new LinearLayout(binding.getRoot().getContext());
        RecyclerView.LayoutParams params = new RecyclerView.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        linearLayout.setLayoutParams(params);
        items.clear();
        for(int i=0;i<dayList.size();i++){
        //创建子布局
            AddItemBinding itemBinding = DataBindingUtil.inflate(LayoutInflater.from(binding.getRoot().getContext()),R.layout.add_item,null,false);
            DynamicItemVM dynamicItemVM =  new DynamicItemVM();
            dynamicItemVM.setDayStr(dayList.get(i));
            if(i==0){
                dynamicItemVM.setSelectBackground(true);
            }else{
                dynamicItemVM.setSelectBackground(false);
            }
            itemBinding.setViewCtrl(dynamicItemVM);
            final int finalI = i;
            itemBinding.text.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    for(int j=0;j<items.size();j++){
                        if(finalI ==j){
                            items.get(j).getViewCtrl().setSelectBackground(true);
                        }else{
                            items.get(j).getViewCtrl().setSelectBackground(false);
                        }
                    }
                }
            });
            items.add(itemBinding);
            linearLayout.addView(itemBinding.getRoot());
        }
        binding.layout.addView(linearLayout);
    }