[Android]RecyclerView的簡單樣本

標籤：android recyclerview

去年google的IO上就展示了一個新的ListView，它就是RecyclerView。

以下是官方的說明，我英語能力有限，不過我大概這麼理解：RecyclerView會比ListView更具有拓展性，使用更有效率，而且更靈活了，具體怎麼樣，時隔一年，我們也發現了它越來越強大，所以有必要去認識一下這個小夥伴了。

The RecyclerView widget is a more advanced and flexible version of ListView. This widget is a container for displaying large data sets that can be scrolled very efficiently by maintaining a limited number of views. Use the RecyclerViewwidget when you have data collections whose elements change at runtime based on user action or network events.

The RecyclerView class simplifies the display and handling of large data sets by providing:

• Layout managers for positioning items
• Default animations for common item operations, such as removal or addition of items

You also have the flexibility to define custom layout managers and animations for RecyclerView widgets.

我們可以在最新版本的support-v7上找到這個玩意兒，本文在v21上找到這個jar的：sdk\extras\android\m2repository\com\android\support\recyclerview-v7\21.0.0，在目錄下將recyclerview-v7-21.0.0.aar解壓，取出classes.jar,你可以更名為：android-support-v7-recyclerview.jar，至少我是這麼乾的。

好了，進入這次demo的主題

1.demo結構

                 

2.樣本

3.讓我們邊看代碼邊瞭解一下，這個控制項吧，首先在介面布局檔案中引入這個組件：

activity_main.xml

<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"    tools:context="${relativePackage}.${activityClass}" >    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:orientation="vertical" >        <RadioGroup            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:checkedButton="@+id/linearlayout_rb"            android:gravity="center_horizontal"            android:orientation="horizontal" >            <RadioButton                android:id="@+id/linearlayout_rb"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="@string/linearlayout" />            <RadioButton                android:id="@+id/gridlayout_rb"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="@string/gridlayout" />        </RadioGroup><span style="white-space:pre"></span>        <android.support.v7.widget.RecyclerView            android:id="@+id/recyclerView"            android:scrollbars="vertical"            android:layout_width="match_parent"            android:layout_height="match_parent" />    </LinearLayout></RelativeLayout>

4.下面就是怎麼使用它，這邊就是簡單的使用方法,在代碼上我已經加上了注釋，簡單理解一下吧。

MainActivity.java

package org.jan.components.demo;import java.util.ArrayList;import org.jan.components.demo.CustomAdapter.OnItemPressedListener;import android.app.Activity;import android.os.Bundle;import android.support.v7.widget.DefaultItemAnimator;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.RecyclerView.RecyclerListener;import android.support.v7.widget.RecyclerView.ViewHolder;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.RadioButton;import android.widget.Toast;/** * android recyclerView的簡單一實例代碼 * @author jan */public class MainActivity extends Activity {private static final String TAG = "MainActivity";private static final String KEY_LAYOUT_MANAGER = "layoutManager";private enum LayoutManagerType {GRID_LAYOUT_MANAGER, LINEAR_LAYOUT_MANAGER}private RadioButton mLinearlayoutButton;private RadioButton mGridLayoutButton;private RecyclerView mRecyclerView;private CustomAdapter mAdapter;private RecyclerView.LayoutManager mLayoutManager;private LayoutManagerType mCurrentLayoutManagerType;//建立的類比資料private ArrayList<String> mDataList;//網格布局中的設定列數private static int SpanCount=3;//類比資料的個數private static int DataSize = 100;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initDatas();initViews(savedInstanceState);}private void initViews(Bundle savedInstanceState) {mLinearlayoutButton = (RadioButton) findViewById(R.id.linearlayout_rb);mLinearlayoutButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {setRecyclerViewManagerType(LayoutManagerType.LINEAR_LAYOUT_MANAGER);}});mGridLayoutButton = (RadioButton) findViewById(R.id.gridlayout_rb);mGridLayoutButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {setRecyclerViewManagerType(LayoutManagerType.GRID_LAYOUT_MANAGER);}});mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;if(savedInstanceState!=null){ mCurrentLayoutManagerType = (LayoutManagerType) savedInstanceState                    .getSerializable(KEY_LAYOUT_MANAGER); Log.i(TAG, "mCurrentLayoutManagerType="+mCurrentLayoutManagerType);}mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);setRecyclerViewManagerType(mCurrentLayoutManagerType);mAdapter = new CustomAdapter(mDataList);mRecyclerView.setAdapter(mAdapter);//設定recycler擁有固定的大小，提高展示效率mRecyclerView.setHasFixedSize(true);//設定預設的動畫，在移除和添加的效果下展現，現在github上可以找到許多拓展，有興趣的可以找找mRecyclerView.setItemAnimator(new DefaultItemAnimator());//實現我們給Adapter監聽的方法，因為recyclerview沒有Listview的OnClick和OnlongClick相似的方法mAdapter.setOnItemPressedListener(new OnItemPressedListener() {@Overridepublic void onItemClick(int position) {Toast.makeText(MainActivity.this, "你點擊了 item-"+mDataList.get(position), Toast.LENGTH_SHORT).show();}@Overridepublic boolean OnItemLongClick(int position) {//這裡類比了刪除的功能removeItemByPosition(position);//insertItemByPosition(position);Toast.makeText(MainActivity.this, "你長按了 item-"+mDataList.get(position), Toast.LENGTH_SHORT).show();return true;}});mRecyclerView.setRecyclerListener(new RecyclerListener() {//資源回收後被調用@Overridepublic void onViewRecycled(ViewHolder viewHolder) {CustomAdapter.ViewHolder vh = (org.jan.components.demo.CustomAdapter.ViewHolder) viewHolder;Log.d(TAG, "onViewRecycled->"+vh.getItemText().getText());}});}//建立類比的資料private void initDatas() {mDataList = new ArrayList<String>();for (int i = 0; i < DataSize; i++) {mDataList.add(String.format(getString(R.string.iamstudent), i));}}/** * 可以改變recycler的布局顯示方式 * @param type */protected void setRecyclerViewManagerType(LayoutManagerType type) {int scrollPosition = 0;if (mRecyclerView.getLayoutManager() != null) {scrollPosition = ((LinearLayoutManager) mRecyclerView.getLayoutManager()).findFirstCompletelyVisibleItemPosition();}switch (type) {//網狀case GRID_LAYOUT_MANAGER:mLayoutManager = new GridLayoutManager(this, SpanCount);mCurrentLayoutManagerType = LayoutManagerType.GRID_LAYOUT_MANAGER;break;//線性，如listcase LINEAR_LAYOUT_MANAGER:mLayoutManager = new LinearLayoutManager(this);mLayoutManager.canScrollHorizontally();mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;break;default:mLayoutManager = new LinearLayoutManager(this);mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;break;}mRecyclerView.setLayoutManager(mLayoutManager);mRecyclerView.scrollToPosition(scrollPosition);}/** * 通過RecyclerView的adapter來移除指定位置的資料 * @param position */protected void removeItemByPosition(int position) {if(mAdapter!=null&&position>0){mAdapter.notifyItemRemoved(position);mDataList.remove(position);mAdapter.notifyItemRangeChanged(position, mAdapter.getItemCount());//你如果用了這個 ，就沒有動畫效果了。//mAdapter.notifyDataSetChanged();}}//對應這是可以新增指定索引的protected void insertItemByPosition(int position) {if(mAdapter!=null&&position>0){mAdapter.notifyItemInserted(position);mDataList.add(position, String.format(getString(R.string.iamstudent), position));mAdapter.notifyItemRangeChanged(position, mAdapter.getItemCount());}}@Overrideprotected void onSaveInstanceState(Bundle outState) {outState.putSerializable(KEY_LAYOUT_MANAGER, mCurrentLayoutManagerType);super.onSaveInstanceState(outState);}@Overrideprotected void onRestoreInstanceState(Bundle savedInstanceState) {super.onRestoreInstanceState(savedInstanceState);}}

5.這個customAdapter是實現了RecyclerView.Adapter，其中的ViewHolder貌似是給我們自己定義的，我沒看過源碼，但我的直覺告訴我他一定是最佳化了ListView對viewholder的重複利用。

package org.jan.components.demo;import java.util.List;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.View.OnLongClickListener;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.TextView;public class CustomAdapter extendsRecyclerView.Adapter<CustomAdapter.ViewHolder> {private List<String> dataList;private OnItemPressedListener onItemPressedListener;public CustomAdapter(List<String> data) {this.dataList = data;}@Overridepublic int getItemCount() {return dataList.size();}//替換視圖內的內容@Overridepublic void onBindViewHolder(ViewHolder viewHolder, int position) {viewHolder.getDrawableId().setBackgroundResource(R.drawable.school_student);viewHolder.getItemText().setText(dataList.get(position));}//由RecyclerView的Layout manager來產生一個新的ViewHolder@Overridepublic ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.layout_row_item, viewGroup, false);return new ViewHolder(v);}/** * 繼承RecyclerView的ViewHolder來自訂一個視圖內的ViewHolder */public class ViewHolder extends RecyclerView.ViewHolder {private ImageView drawableId;private TextView itemText;public ViewHolder(View itemView) {super(itemView);if(itemView!=null){//這裡我為這個View添加了點擊和長按事件的監聽綁定，為了使本demo更像一個listViewitemView.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {if(onItemPressedListener!=null){onItemPressedListener.onItemClick(getPosition());}}});itemView.setOnLongClickListener(new OnLongClickListener() {@Overridepublic boolean onLongClick(View v) {if(onItemPressedListener!=null){return onItemPressedListener.OnItemLongClick(getPosition());}return false;}});drawableId = (ImageView) itemView.findViewById(R.id.item_image);itemText = (TextView) itemView.findViewById(R.id.item_text);}}public ImageView getDrawableId() {return drawableId;}public TextView getItemText() {return itemText;}}public void setOnItemPressedListener(OnItemPressedListener onItemPressedListener) {this.onItemPressedListener = onItemPressedListener;}protected static interface OnItemPressedListener{void onItemClick(int position);boolean OnItemLongClick(int position);}}

好，代碼都講的很清楚簡潔，主要是為了增加對RecyclerView的認識，現在很多新的app，都已經加入了這組件，很多大牛也寫了對他的強大的拓展。

我在這裡也添加一個有進階性的博文，可供你我有時間學習

Android RecyclerView 使用完全解析 體驗藝術般的控制項

[Android]使用RecyclerView替代ListView（二）

著作權聲明：本文為博主原創文章，未經博主允許不得轉載。

[Android]RecyclerView的簡單樣本