Android應(yīng)用開發(fā)中RecyclerView組件使用入門教程

更新時間：2016年02月24日 18:13:03 作者：SpikeKing

這篇文章主要介紹了Android應(yīng)用開發(fā)中RecyclerView組件使用的入門教程,RecyclerView主要針對安卓5.0以上的material design開發(fā)提供支持,需要的朋友可以參考下

RecyclerView是一種列表容器, 發(fā)布很久了, 才想起來寫點什么.

RecyclerView相比于ListView, 在回收重用時更具有靈活性, 也就是低耦合, 并且提供了擴(kuò)展. 加載多個視圖時, 應(yīng)該多用RecyclerView代替ListView.

那么我們來看看這東西應(yīng)該怎么用? 比如生成一個瀑布流的視圖.

2016224180636421.png (1080×1920)

首先我們從一個HelloWorld寫起, 看看如何構(gòu)建一個RecyclerView.

1. 依賴庫
Gradle配置, 添加Recycler庫

compile 'com.android.support:recyclerview-v7:+'

2. 資源文件
資源文件

 <android.support.v7.widget.RecyclerView
  android:id="@+id/test_recycler_view"
  android:layout_width="match_parent"
  android:layout_height="match_parent"/>

3. 代碼
LayoutManager: 管理RecyclerView的結(jié)構(gòu).
Adapter: 處理每個Item的顯示.
ItemDecoration: 添加每個Item的裝飾.
ItemAnimator: 負(fù)責(zé)添加\移除\重排序時的動畫效果.

LayoutManager\Adapter是必須, ItemDecoration\ItemAnimator是可選.
 /**
  * 初始化RecyclerView
  *
  * @param recyclerView 主控件
  */
 private void initRecyclerView(RecyclerView recyclerView) {
  recyclerView.setHasFixedSize(true); // 設(shè)置固定大小
  initRecyclerLayoutManager(recyclerView); // 初始化布局
  initRecyclerAdapter(recyclerView); // 初始化適配器
  initItemDecoration(recyclerView); // 初始化裝飾
  initItemAnimator(recyclerView); // 初始化動畫效果
 }

4. LayoutManager
管理RecyclerView的布局結(jié)構(gòu).

 private void initRecyclerLayoutManager(RecyclerView recyclerView) {
  // 錯列網(wǎng)格布局
  recyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,
    StaggeredGridLayoutManager.VERTICAL));
 }

提供了多種LayoutManager, 瀑布流使用錯列網(wǎng)格布局.
5. Adapter
適配器, 處理RecyclerView的Item事務(wù).

 private void initRecyclerAdapter(RecyclerView recyclerView) {
  mAdapter = new MyAdapter(getData());
  recyclerView.setAdapter(mAdapter);
 }

對于Adapter, 我們需要展開來說, 先看看類.

public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {

 private List<DataModel> mDataModels;
 private List<Integer> mHeights;

 MyAdapter(List<DataModel> dataModels) {
  if (dataModels == null) {
   throw new IllegalArgumentException("DataModel must not be null");
  }
  mDataModels = dataModels;
  mHeights = new ArrayList<>();
 }

 @Override
 public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
  View itemView = LayoutInflater.from(parent.getContext())
    .inflate(R.layout.item_recycler_view, parent, false);
  return new MyViewHolder(itemView);
 }

 @Override
 public void onBindViewHolder(MyViewHolder holder, int position) {
  DataModel dataModel = mDataModels.get(position);

  // 隨機(jī)高度, 模擬瀑布效果.
  if (mHeights.size() <= position) {
   mHeights.add((int) (100 + Math.random() * 300));
  }

  ViewGroup.LayoutParams lp = holder.getTvLabel().getLayoutParams();
  lp.height = mHeights.get(position);

  holder.getTvLabel().setLayoutParams(lp);

  holder.getTvLabel().setText(dataModel.getLabel());
  holder.getTvDateTime().setText(new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH)
    .format(dataModel.getDateTime()));
 }

 @Override
 public int getItemCount() {
  return mDataModels.size();
 }

 public void addData(int position) {
  DataModel model = new DataModel();
  model.setDateTime(getBeforeDay(new Date(), position));
  model.setLabel("No. " + (int) (new Random().nextDouble() * 20.0f));

  mDataModels.add(position, model);
  notifyItemInserted(position);
 }

 public void removeData(int position) {
  mDataModels.remove(position);
  notifyItemRemoved(position);
 }

 /**
  * 獲取日期的前一天
  *
  * @param date 日期
  * @param i 偏離
  * @return 新的日期
  */
 private static Date getBeforeDay(Date date, int i) {
  Calendar calendar = Calendar.getInstance();
  calendar.setTime(date);
  calendar.add(Calendar.DAY_OF_YEAR, i * (-1));
  return calendar.getTime();
 }
}

（1）onCreateViewHolder創(chuàng)建ViewHolder.

（2）onBindViewHolder綁定每一項數(shù)據(jù).

（3）getItemCount返回列表長度.

（4）RecyclerView強(qiáng)制使用ViewHolder.

public class MyViewHolder extends RecyclerView.ViewHolder {

 private TextView mTvLabel; // 標(biāo)簽
 private TextView mTvDateTime; // 日期

 public MyViewHolder(View itemView) {
  super(itemView);
  mTvLabel = (TextView) itemView.findViewById(R.id.item_text);
  mTvDateTime = (TextView) itemView.findViewById(R.id.item_date);
 }

 public TextView getTvLabel() {
  return mTvLabel;
 }

 public TextView getTvDateTime() {
  return mTvDateTime;
 }

}

在onCreateViewHolder方法, 創(chuàng)建類; 在onBindViewHolder方法, 綁定數(shù)據(jù).
DataModel

public class DataModel {

 private String mLabel;
 private Date mDateTime;

 public String getLabel() {
  return mLabel;
 }

 public void setLabel(String label) {
  mLabel = label;
 }

 public Date getDateTime() {
  return mDateTime;
 }

 public void setDateTime(Date dateTime) {
  mDateTime = dateTime;
 }
}

6. ItemDecoration
項的裝飾, 比如ListView中的分割線, 在本例中, 左右兩條粉線.

 private void initItemDecoration(RecyclerView recyclerView) {
  recyclerView.addItemDecoration(new MyItemDecoration(this));
 }

ItemDecoration, 注意parent和child的使用方式.

public class MyItemDecoration extends RecyclerView.ItemDecoration {

 private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
 private Drawable mDivider;

 public MyItemDecoration(Context context) {
  final TypedArray array = context.obtainStyledAttributes(ATTRS);
  mDivider = array.getDrawable(0);
  array.recycle();
 }

 @Override
 public void onDraw(Canvas c, RecyclerView parent, State state) {
  drawHorizontal(c, parent);
  drawVertical(c, parent);
 }

 // 水平線
 public void drawHorizontal(Canvas c, RecyclerView parent) {

  final int childCount = parent.getChildCount();

  // 在每一個子控件的底部畫線
  for (int i = 0; i < childCount; i++) {
   final View child = parent.getChildAt(i);

   final int left = child.getLeft() + child.getPaddingLeft();
   final int right = child.getWidth() + child.getLeft() - child.getPaddingRight();
   final int top = child.getBottom() - mDivider.getIntrinsicHeight() - child.getPaddingBottom();
   final int bottom = top + mDivider.getIntrinsicHeight();
   mDivider.setBounds(left, top, right, bottom);
   mDivider.draw(c);
  }
 }

 // 豎直線
 public void drawVertical(Canvas c, RecyclerView parent) {

  final int childCount = parent.getChildCount();

  // 在每一個子控件的右側(cè)畫線
  for (int i = 0; i < childCount; i++) {
   final View child = parent.getChildAt(i);
   int right = child.getRight() - child.getPaddingRight();
   int left = right - mDivider.getIntrinsicWidth();
   final int top = child.getTop() + child.getPaddingTop();
   final int bottom = child.getTop() + child.getHeight() - child.getPaddingBottom();

   mDivider.setBounds(left, top, right, bottom);
   mDivider.draw(c);
  }
 }

 // Item之間的留白
 @Override
 public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {
  outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight());
 }
}

本例重寫了listDivider

 <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
  ...
  <item name="android:listDivider">@drawable/divider_bg</item>
 </style>
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
  android:shape="rectangle">
 <solid android:color="#ff00ff"/>
 <size android:height="4dp"/>
 <size android:width="4dp"/>
</shape>

7. ItemAnimator
動畫效果比較復(fù)雜, 使用默認(rèn)動畫. 如要定制的話, 繼承DefaultItemAnimator; 如設(shè)置null, 則不顯示任何動畫.

 private void initItemAnimator(RecyclerView recyclerView) {
  recyclerView.setItemAnimator(new DefaultItemAnimator()); // 默認(rèn)動畫
 }

8. 最終Activity

public class MainActivity extends AppCompatActivity {

 private MyAdapter mAdapter;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
  setSupportActionBar(toolbar);

  FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
  fab.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
    Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
      .setAction("Action", null).show();
   }
  });

  // 初始化RecyclerView
  initRecyclerView((RecyclerView) findViewById(R.id.test_recycler_view));
 }

 /**
  * 初始化RecyclerView
  *
  * @param recyclerView 主控件
  */
 private void initRecyclerView(RecyclerView recyclerView) {
  recyclerView.setHasFixedSize(true); // 設(shè)置固定大小
  initRecyclerLayoutManager(recyclerView); // 初始化LayoutManager
  initRecyclerAdapter(recyclerView); // 初始化Adapter
  initItemDecoration(recyclerView); // 初始化邊界裝飾
  initItemAnimator(recyclerView); // 初始化動畫效果
 }

 /**
  * 初始化RecyclerView的LayoutManager
  *
  * @param recyclerView 主控件
  */
 private void initRecyclerLayoutManager(RecyclerView recyclerView) {
  // 錯列網(wǎng)格布局
  recyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,
    StaggeredGridLayoutManager.VERTICAL));
 }

 /**
  * 初始化RecyclerView的Adapter
  *
  * @param recyclerView 主控件
  */
 private void initRecyclerAdapter(RecyclerView recyclerView) {
  mAdapter = new MyAdapter(getData());
  recyclerView.setAdapter(mAdapter);
 }

 /**
  * 初始化RecyclerView的(ItemDecoration)項目裝飾
  *
  * @param recyclerView 主控件
  */
 private void initItemDecoration(RecyclerView recyclerView) {
  recyclerView.addItemDecoration(new MyItemDecoration(this));
 }

 /**
  * 初始化RecyclerView的(ItemAnimator)項目動畫
  *
  * @param recyclerView 主控件
  */
 private void initItemAnimator(RecyclerView recyclerView) {
  recyclerView.setItemAnimator(new DefaultItemAnimator()); // 默認(rèn)動畫
 }

 /**
  * 模擬的數(shù)據(jù)
  *
  * @return 數(shù)據(jù)
  */
 private ArrayList<DataModel> getData() {
  int count = 57;
  ArrayList<DataModel> data = new ArrayList<>();
  for (int i = 0; i < count; i++) {
   DataModel model = new DataModel();

   model.setDateTime(getBeforeDay(new Date(), i));
   model.setLabel("No. " + i);

   data.add(model);
  }

  return data;
 }

 /**
  * 獲取日期的前一天
  *
  * @param date 日期
  * @param i 偏離
  * @return 新的日期
  */
 private static Date getBeforeDay(Date date, int i) {
  Calendar calendar = Calendar.getInstance();
  calendar.setTime(date);
  calendar.add(Calendar.DAY_OF_YEAR, i * (-1));
  return calendar.getTime();
 }


 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.menu_main, menu);
  return true;
 }

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
  // Handle action bar item clicks here. The action bar will
  // automatically handle clicks on the Home/Up button, so long
  // as you specify a parent activity in AndroidManifest.xml.
  int id = item.getItemId();

  switch (item.getItemId()) {
   case R.id.id_action_add:
    mAdapter.addData(1);
    break;
   case R.id.id_action_delete:
    mAdapter.removeData(1);
    break;
  }

  //noinspection SimplifiableIfStatement
  if (id == R.id.action_settings) {
   return true;

  }

  return super.onOptionsItemSelected(item);
 }
}

為了測試動畫, Menu額外添加兩個按鈕。

9.運行ReactNative示例
既然感覺ReactNative開發(fā)靠譜, 那么我們就來看看ReactNative都能做哪些好玩的東西, 和原生的有哪些區(qū)別?
示例圖

2016224180350086.jpg (750×1334)

2016224180414706.jpg (1080×1920)

按照文檔安裝一些命令行工具, 再下載Git代碼.
Github: https://github.com/facebook/react-native

內(nèi)容很多, 包含一些依賴庫和示例(Example), 下載的有點慢, 耐心等待.

下載完成后, 在react-native內(nèi), 執(zhí)行npm install.

Android項目執(zhí)行, 參考ReactAndroid的README.md.

在react-native目錄, 新建local.properties

sdk.dir=/Users/wangchenlong/Installations/android-sdk
ndk.dir=/Users/wangchenlong/Installations/android-ndk-r10e

執(zhí)行

cd react-native
./gradlew :ReactAndroid:assembleDebug

再執(zhí)行

./gradlew :ReactAndroid:installArchives

啟動服務(wù)

./packager/packager.sh

安裝項目

cd react-native
./gradlew :Examples:UIExplorer:android:app:installDebug

一定要先啟動服務(wù), 再安裝項目.
出現(xiàn)transforming 100%, 即導(dǎo)入成功.

2016224180504265.jpg (570×366)

在最新版本中, 我的紅米note4無法運行項目.
報錯: Upload package to device fails.
原因是編譯的gradle版本太高, 默認(rèn)1.5.0, 實際1.2.0~1.3.0都可以運行.
我的是1.2.3.
真機(jī)調(diào)試, 本人紅米note(Android 4.2)
搖動手機(jī), 選擇Dev Settings->Debug sever host & port for device. 設(shè)置IP地址, 觀察本機(jī)的IP, 填入即可. 我當(dāng)前的是

192.168.2.202:8081
注意設(shè)置端口8081, 否則無法加載. 有些情況可以直接輸入IP即可.
Android5.0以上, 直接設(shè)置端口即可.