使用RecyclerView实现多样的View

根据（https://developer.android.com/intl/zh-cn/training/material/lists-cards.html）简单的学习了使用RecyclerView 和 CardView 来创建列表与卡片后，就想怎么让一个RecyclerView 根据数据呈现不同类型的CardView.

第一步

RecyclerView和Cardview 是Support Library的一部分。所以需要在app/build.gradle中添加以下依赖，才能立即使用

compile 'com.android.support:cardview-v7:24.0.0-alpha1'
compile 'com.android.support:recyclerview-v7:24.0.0-alpha1'

第二步

创建cardview 和RecyclerView

cardviewone.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView 
xmlns:android="http://schemas.android.com/apk/res/android"    
xmlns:app="http://schemas.android.com/apk/res-auto"    
android:orientation="vertical"    
android:layout_width="match_parent"    
android:layout_height="160dp"    
app:cardElevation="8dp"    
android:layout_marginTop="4dp"    
android:layout_margin="16dp"    
app:cardBackgroundColor="@color/title_cardview">    
    <RelativeLayout        
      android:layout_width="match_parent"        
      android:layout_height="match_parent">        
   <TextView android:layout_width="wrap_content"            
      android:layout_height="wrap_content"            
      android:textSize="16sp"            
      android:id="@+id/text"            
      android:textColor="@color/white"            
      android:layout_margin="16dp"            
      android:text="日期"/>        
  <TextView              
      android:layout_width="wrap_content"              
      android:layout_height="wrap_content"           
      android:id="@+id/date"            
      android:text="@string/date"            
      android:textSize="16sp"            
      android:textColor="@color/white"            
      android:layout_marginLeft="0dp"            
      android:layout_alignTop="@+id/text"            
      android:layout_toEndOf="@+id/text" />        
   <TextView            
      android:layout_width="wrap_content"            
      android:layout_height="wrap_content"            
      android:textColor="@color/white"            
      android:textSize="32sp"            
      android:text="@string/task"            
      android:layout_below="@+id/text"            
      android:layout_alignStart="@+id/text"           
      android:id="@+id/textView" />        
    <Button           
     android:layout_width="wrap_content"            
     android:layout_height="wrap_content"            
     android:text="添加任务"            
     android:textColor="@color/white"            
     style="?attr/borderlessButtonStyle"            
     android:id="@+id/button"            
     android:layout_above="@+id/textView"            
     android:layout_alignParentEnd="true"            
     android:layout_marginEnd="25dp" />    
  </RelativeLayout>
</android.support.v7.widget.CardView>

cardviewtwo.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView      
  xmlns:android="http://schemas.android.com/apk/res/android"    
  xmlns:app="http://schemas.android.com/apk/res-auto"    
  android:orientation="vertical"    
  android:layout_width="match_parent"    
  android:layout_height="160dp"    
  app:cardElevation="8dp"    
  android:layout_marginTop="4dp"    
  android:layout_margin="16dp">    
  <RelativeLayout        
     android:layout_width="match_parent"        
     android:layout_height="match_parent">  
  <TextView android:layout_width="wrap_content"      
    android:layout_height="wrap_content"      
    android:textSize="24sp"      
    android:id="@+id/text"      
    android:layout_margin="16dp"      
    android:text="我是天气预报哦"/>  
  <TextView      
    android:layout_width="wrap_content"      
    android:layout_height="wrap_content"      
    android:id="@+id/score"      
    android:text="32℃"      
    android:textSize="72sp"      
    android:layout_marginLeft="0dp"      
    android:layout_below="@+id/text"      
    android:layout_alignStart="@+id/text" />    
</RelativeLayout>
</android.support.v7.widget.CardView>

main_activity.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
   xmlns:tools="http://schemas.android.com/tools"  
   xmlns:app="http://schemas.android.com/apk/res-auto"  
  android:layout_width="match_parent"   
  android:layout_height="match_parent"    
  tools:context=".MainActivity"    
  android:orientation="vertical">    
<android.support.v7.widget.Toolbar        
  android:id="@+id/toolbar"        
  android:layout_width="match_parent"       
  android:layout_height="?attr/actionBarSize"        
  android:background="#ffffff"        
  app:elevation="1dp"        
  app:theme="@style/AppTheme"        >        
<TextView            
  android:layout_width="wrap_content"            
  android:layout_height="wrap_content"            
  android:layout_gravity="center"            
  android:text="我是APP"            
android:textSize="@dimen/abc_text_size_title_material_toolbar">        
</TextView>    
</android.support.v7.widget.Toolbar>    
<android.support.v7.widget.RecyclerView        
  android:id="@+id/recyclerview"        
  android:layout_width="match_parent"        
  android:layout_height="match_parent"        
   >
</android.support.v7.widget.RecyclerView>
</LinearLayout>

在MainActivity中设置RecicylerView

RecyclerView recyclerView = (RecyclerView) 
findViewById(R.id.recyclerview);RecyclerView.LayoutManager layoutManager = new 
LinearLayoutManager(this);recyclerView.setLayoutManager(layoutManager);MyRecyclerAdapter 
myRecyclerAdapter =new MyRecyclerAdapter(itemList,this);recyclerView.setAdapter(myRecyclerAdapter);

itemList是一个 ArrayList<Data>，Data是一个自定义的类，等会我们会根据这里面的状态值来确定我们哪一个CardView

第三步

自定义一个RecyclerView.Adapter
想要让它显示各种各样的View的话,主要靠的是重载getItemViewType函数

@Override
public int getItemViewType(int position) {
    return ItemList.get(position).getType();
} 

为每一种View设置一个ViewHolder类

 public class OneViewHolder extends CustomViewHolder { 
  private TextView date; private TextView task; 
  private Button add; 
  public OneViewHolder(View itemView) { 
    super(itemView); date = (TextView)itemView.findViewById(R.id.date); 
    task = (TextView)itemView.findViewById(R.id.textView); 
    add = (Button)itemView.findViewById(R.id.button); 
    }
   } 
  public class TwoViewHolder extends CustomViewHolder { 
    private TextView date; 
    private TextView temp; 
    public TwoViewHolder(View itemView) { 
        super(itemView); 
        date = (TextView)itemView.findViewById(R.id.text); 
        temp = (TextView)itemView.findViewById(R.id.score); 
     }
    }

重载onCreateViewHolder函数

  private static final int TASK = 1; 
  private static final int WEATHER =2;
  @Override 
  public CustomViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    if(TASK == viewType) {
          View v = LayoutInflater.from(mcontext).inflate(R.layout.cardview_one,parent,false); 
          return new OneViewHolder(v); 
       } else if(WEATHER == viewType) {
          View v = LayoutInflater.from(mcontext).inflate(R.layout.cardview_two,parent,false); 
          return new TwoViewHolder(v); 
      } 
        return null; 
      }

期中 *viewType 就是之前getItemViewType ***返回的拉

最后一步：onBindViewHolder()绑定数据到正确的Item视图上。

 @Override 
public void onBindViewHolder(CustomViewHolder holder, int position) { 
    int type = ItemList.get(position).type; 
    switch (type){ 
    case TASK: 
            OneViewHolder oneViewHolder = (OneViewHolder)holder;     
            oneViewHolder.date.setText(ItemList.get(position).getData1()); 
            oneViewHolder.task.setText(ItemList.get(position).getData2()); 
            break; 
    case WEATHER: 
            TwoViewHolder twoViewHolder = (TwoViewHolder)holder; 
            twoViewHolder.date.setText(ItemList.get(position).getData1()); 
            twoViewHolder.temp.setText(ItemList.get(position).getData2()); 
            break; 
      } 
  }

我自己定义的Data.Class

public class Data{    
  private int type;    
  private String data1;    
  private String data2;    
  public Data(String data1, String data2, int type) {        
  this.data1 = data1;        
  this.data2 = data2;        
  this.type = type;    
  }    
public String getData1() { 
       return data1;   
 }    
public String getData2() {
        return data2;    
  }    
public int getType() {        
  return type;    
  }
 }

效果图：虽然丑了一点，但还可以啦

Paste_Image.png