RecyclerView使用

JonFullerto 9年前

来自: http://my.oschina.net/gef/blog/607017


android.support.v7.widget.RecyclerView是v7包里的一个widget,非常强大的一个控件,完全可以代替listview,gridview和瀑布流。

这里主要讲三点:

  1. 为recyclerView设置LayoutManager

  2. RecyclerView.Adapter

  3. 删除和添加数据的动画效果展示

1.

RecyclerView中有三种LayoutManager,如下:

LayoutManager
Orientation
LinearLayoutManager HORIZONTAL、VERTICAL
GridLayoutManager HORIZONTAL、VERTICAL
StaggeredGridLayoutManager HORIZONTAL、VERTICAL
解释一下若设置成 LinearLayoutManager,就和ListView的展示效果基本一样,但人家还可以当作水平方向的listView;若设置GridLayoutManager就相当于girdView,同样可以设置成水平方向滑动;若设置成StaggeredGridLayoutManager,就是瀑布流了,同样可以设置成水平方向滑动。

例如:

LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);  linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);  //设置layoutmanager  recyclerView.setLayoutManager(linearLayoutManager);

2.RecyclerView.Adapter

    这个RecyclerView.Adapter可不得了啊,首先可以带范型,看源码:

public static abstract class Adapter<VH extends ViewHolder> {。。。}

然后是个抽象类,举个例子:

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>{        @Override      public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {          View view = View.inflate(parent.getContext(),R.layout.myview,null);          ViewHolder viewHolder = new ViewHolder(view);          return viewHolder;      }        @Override      public void onBindViewHolder(ViewHolder holder, int position) {          holder.content.setText(arrayList.get(position));        }        @Override      public int getItemCount() {          return arrayList.size();      }      public class ViewHolder extends RecyclerView.ViewHolder{            private TextView content;          public ViewHolder(View itemView) {              super(itemView);              content = (TextView) ((FrameLayout) itemView).getChildAt(0);          }      }  }

这里我自定了一个ViewHolder继承RecyclerView.ViewHolder,说一下MyAdapter的执行流程:首先执行onCreateViewHolder方法,返回了我们自定义的ViewHolder,然后onBindViewHolder方法。可以看出RecyclerView.Adapter对ViewHolder进行了封装。

3.删除和添加数据的动画效果展示,如果是baseAdapter怎么刷新呢,调用notifyDataSetChanged()方法,那在使用RecyclerView时呢:

notifyItemInserted(int position);  notifyItemRemoved(int position);

而且还有动画效果。

好了来个例子:

R.layout.activity_recycler_view文件:

<?xml version="1.0" encoding="utf-8"?>  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:tools="http://schemas.android.com/tools"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:paddingBottom="@dimen/activity_vertical_margin"      android:paddingLeft="@dimen/activity_horizontal_margin"      android:paddingRight="@dimen/activity_horizontal_margin"      android:paddingTop="@dimen/activity_vertical_margin"      tools:context="com.sumu.gefdemo.activity.RecyclerViewActivity">        <android.support.v7.widget.RecyclerView          android:id="@+id/recyclerview"          android:layout_width="match_parent"          android:layout_height="match_parent">        </android.support.v7.widget.RecyclerView>  </RelativeLayout>

actiivty中:

package com.sumu.gefdemo.activity;    import android.os.Bundle;  import android.support.v7.app.AppCompatActivity;  import android.support.v7.widget.GridLayoutManager;  import android.support.v7.widget.LinearLayoutManager;  import android.support.v7.widget.RecyclerView;  import android.support.v7.widget.StaggeredGridLayoutManager;  import android.view.Menu;  import android.view.MenuItem;  import android.view.View;  import android.view.ViewGroup;  import android.widget.FrameLayout;  import android.widget.TextView;    import com.sumu.gefdemo.R;    import java.util.ArrayList;  import java.util.Random;    public class RecyclerViewActivity extends AppCompatActivity {      private RecyclerView recyclerView;      private MyAdapter myAdapter;        private ArrayList<String> arrayList = new ArrayList<>();      @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_recycler_view);          recyclerView = (RecyclerView) findViewById(R.id.recyclerview);          /**           * 三种LayoutManager           */          //1          LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);          linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);          //2.          GridLayoutManager gridLayoutManager = new GridLayoutManager(this,4);          gridLayoutManager.setOrientation(GridLayoutManager.HORIZONTAL);          //3.          StaggeredGridLayoutManager staggeredGridLayoutManager = new StaggeredGridLayoutManager(4,StaggeredGridLayoutManager.VERTICAL);          //设置layoutmanager          recyclerView.setLayoutManager(staggeredGridLayoutManager);            Random random = new Random();            for (int i = 0;i < 100;i++){              random.nextInt();              arrayList.add(i + "gefufeng" + random.nextInt(10000000));          }          myAdapter = new MyAdapter();          recyclerView.setAdapter(myAdapter);      }      public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>{            @Override          public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {              View view = View.inflate(parent.getContext(),R.layout.myview,null);              ViewHolder viewHolder = new ViewHolder(view);              return viewHolder;          }            @Override          public void onBindViewHolder(ViewHolder holder, int position) {              holder.content.setText(arrayList.get(position));            }            @Override          public int getItemCount() {              return arrayList.size();          }          public class ViewHolder extends RecyclerView.ViewHolder{                private TextView content;              public ViewHolder(View itemView) {                  super(itemView);                  content = (TextView) ((FrameLayout) itemView).getChildAt(0);              }          }      }        @Override      public boolean onCreateOptionsMenu(Menu menu) {          menu.add(0,1,1,"add");          menu.add(Menu.NONE,2,2,"delete");          return true;        }        @Override      public boolean onOptionsItemSelected(MenuItem item) {          if (item.getItemId() == 1){              arrayList.add(1,"gefufenggefufenggefufenggefufenggefufeng");              myAdapter.notifyItemInserted(1);          }else{              arrayList.remove(2);              myAdapter.notifyItemRemoved(2);          }          return super.onOptionsItemSelected(item);      }  }

R.layout.myview文件:

<?xml version="1.0" encoding="utf-8"?>  <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      >      <TextView          android:padding="10dp"          android:background="#3f3"          android:gravity="center"          android:text="gefufebg"          android:layout_margin="10dp"          android:layout_width="wrap_content"          android:layout_height="wrap_content"           />    </FrameLayout>

效果图(其中之一):