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Android RecyclerView實(shí)現(xiàn)多種item布局的方法

 更新時(shí)間：2017年12月06日 09:38:45   作者：xiyouZmt  
本篇文章主要介紹了Android RecyclerView實(shí)現(xiàn)多種item布局的方法，小編覺(jué)得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過(guò)來(lái)看看吧

在項(xiàng)目中列表是基本都會(huì)用到的，然而在顯示列表時(shí)，我們需要的數(shù)據(jù)可能需要不止一種item顯示，對(duì)于復(fù)雜的數(shù)據(jù)就需要多種item，以不同的樣式顯示出來(lái)，這樣效果是很棒的，我們先看一下效果

我們可以看到，這個(gè)RecyclerView中有多種item顯示出來(lái)，那么具體怎么實(shí)現(xiàn)呢，其實(shí)在RecyclerView中，我們可以重寫(xiě)方法getItemViewType()，這個(gè)方法會(huì)傳進(jìn)一個(gè)參數(shù)position表示當(dāng)前是第幾個(gè)Item，然后我們可以通過(guò)position拿到當(dāng)前的Item對(duì)象，然后判斷這個(gè)item對(duì)象需要那種視圖，返回一個(gè)int類型的視圖標(biāo)志，然后在onCreatViewHolder方法中給引入布局，這樣就能夠?qū)崿F(xiàn)多種item顯示了，講了這么多我們看一下具體的例子

@Override 
public int getItemViewType(int position) { 
  if(list.size() == 0){ 
    return EMPTY_VIEW; 
  } else if(list.get(position) == null){ 
    return PROGRESS_VIEW; 
  } else if(list.get(position).getType().equals(News.IMAGE_NEWS)){ 
    return IMAGE_VIEW; 
  } else { 
    return super.getItemViewType(position); 
  } 
}

首先我們重寫(xiě)了getItemViewType這個(gè)方法，在這個(gè)方法中根據(jù)position對(duì)item對(duì)象做了一些判斷，如果存儲(chǔ)item對(duì)象的集合大小為空，返回空view標(biāo)識(shí)（這里為1），如果item對(duì)象為null，返回進(jìn)度條標(biāo)識(shí)，這個(gè)主要是用于實(shí)現(xiàn)下拉加載更多，如果item對(duì)象類型屬于圖片類型，就返回圖片類型對(duì)應(yīng)的Item，這個(gè)就是效果圖中的第一個(gè)Item類型，否則就是其它類型，也就是效果圖中的另一種item布局，然后我們?cè)趏nCreatViewHolder中具體的為每一種類型引入其布局

@Override 
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
  View view; 
  if(viewType == PROGRESS_VIEW){ 
    view = LayoutInflater.from(parent.getContext()).inflate(R.layout.progressbar_item, parent, false); 
    return new ProgressViewHolder(view); 
  } else if(viewType == EMPTY_VIEW){ 
    return null; 
  } else if(viewType == IMAGE_VIEW){ 
    view = LayoutInflater.from(parent.getContext()).inflate(R.layout.image_news_item, parent, false); 
    return new ImageViewHolder(view); 
  } else { 
    view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_item, parent, false); 
    return new NewsViewHolder(view); 
  } 
}

上面的代碼就是具體為每種viewType引入其對(duì)應(yīng)的布局，這樣就基本實(shí)現(xiàn)了多種item布局，但是僅僅是這些還不夠，因?yàn)槲覀冞€要對(duì)每種item設(shè)置數(shù)據(jù)，所以還要對(duì)每種item寫(xiě)一個(gè)VIewHolder來(lái)為item顯示數(shù)據(jù)

class NewsViewHolder extends RecyclerView.ViewHolder{  
  @BindView(R.id.news_title)TextView title; 
  @BindView(R.id.news_digest)TextView digest; 
  @BindView(R.id.news_time)TextView time; 
  @BindView(R.id.news_src)ImageView image;  
  public NewsViewHolder(View itemView) { 
    super(itemView); 
    ButterKnife.bind(this, itemView); 
  } 
} 
 
class ImageViewHolder extends RecyclerView.ViewHolder{  
  @BindView(R.id.news_title) TextView title; 
  @BindView(R.id.image_left) ImageView imageLeft; 
  @BindView(R.id.image_right) ImageView imageRight; 
  @BindView(R.id.image_middle) ImageView imageMiddle; 
  @BindView(R.id.news_time) TextView time;  
  public ImageViewHolder(View itemView) { 
    super(itemView); 
    ButterKnife.bind(this, itemView); 
  } 
} 
 
class ProgressViewHolder extends RecyclerView.ViewHolder {  
  @BindView(R.id.progressBar) ProgressBar progressBar; 
  @BindView(R.id.textView) TextView textView;  
  public ProgressViewHolder(View itemView) { 
    super(itemView); 
    ButterKnife.bind(this, itemView); 
  } 
}

上面就是item對(duì)應(yīng)的幾個(gè)ViewHolder，判斷viewHolder屬于那種對(duì)象，然后在onBindViewHolder中根據(jù)對(duì)應(yīng)的ViewHolder對(duì)其控件設(shè)置數(shù)據(jù)并顯示

@Override 
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) { 
  holder.itemView.setOnClickListener(new View.OnClickListener() { 
    @Override 
    public void onClick(View v) { 
      clickListener.onItemClick(v, position); 
    } 
  }); 
  if(holder instanceof NewsViewHolder){ 
    NewsViewHolder viewHolder = (NewsViewHolder)holder; 
    viewHolder.title.setText(list.get(position).getTitle()); 
    viewHolder.time.setText(list.get(position).getTime()); 
    /** 
     * Glide加載圖片 
     */ 
    Glide.with(context).load(list.get(position).getImageUrl().get(0)) 
        .override(dpToPx(72), dpToPx(72)).centerCrop().into(viewHolder.image); 
    if(list.get(position).getType().equals(News.TEXT_NEWS)){ 
      viewHolder.digest.setText(list.get(position).getDigest()); 
    } else { 
      viewHolder.digest.setText(""); 
    } 
  } else if(holder instanceof ImageViewHolder){ 
    ImageViewHolder viewHolder = (ImageViewHolder)holder; 
    viewHolder.title.setText(list.get(position).getTitle()); 
    viewHolder.time.setText(list.get(position).getTime()); 
    setItemImage(viewHolder, list, position); 
  } else if(holder instanceof ProgressViewHolder){ 
    ProgressViewHolder viewHolder = (ProgressViewHolder)holder; 
    viewHolder.progressBar.setIndeterminate(true); 
 
  } 
}

整個(gè)過(guò)程基本就是這樣，這種方式在項(xiàng)目中經(jīng)常會(huì)用到，我們就可以這樣去處理，下拉加載更多就可以這樣實(shí)現(xiàn)，在加載完數(shù)據(jù)后再往對(duì)象集合中傳入null，然后判斷如果出現(xiàn)null就加載progressBar布局，再加上Google官方的SwipeRefreshLayout，下拉刷新，上拉加載就搞定了，其實(shí)很容易，而且也有點(diǎn)Material Design 的感覺(jué)~~~~~~

看下Adapter的全部代碼

package com.zmt.e_read.Adapter;  
import android.content.Context; 
import android.support.v7.widget.RecyclerView; 
import android.util.DisplayMetrics; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ImageView; 
import android.widget.TextView;  
import com.bumptech.glide.Glide; 
import com.zmt.e_read.Module.News; 
import com.zmt.e_read.Module.OnItemClickListener; 
import com.zmt.e_read.R; 
import com.zmt.e_read.Utils.ProgressViewHolder; 
import java.util.Collection; 
import java.util.Collections; 
import java.util.List; 
import butterknife.BindView; 
import butterknife.ButterKnife;  
/** 
 * Created by Dangelo on 2016/9/27. 
 */ 
public class NewsAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> { 
  private final int EMPTY_VIEW = 1; 
  private final int PROGRESS_VIEW = 2; 
  private final int IMAGE_VIEW = 3; 
  private Context context; 
  private List<News> list; 
  private OnItemClickListener clickListener; 
 
  public NewsAdapter(Context context, List<News> list, OnItemClickListener clickListener) { 
    this.context = context; 
    this.list = list; 
    this.clickListener = clickListener; 
  } 
 
  public void addOnItemClickListener(OnItemClickListener clickListener){ 
    this.clickListener = clickListener; 
  } 
 
  @Override 
  public int getItemViewType(int position) { 
    if(list.size() == 0){ 
      return EMPTY_VIEW; 
    } else if(list.get(position) == null){ 
      return PROGRESS_VIEW; 
    } else if(list.get(position).getType().equals(News.IMAGE_NEWS)){ 
      return IMAGE_VIEW; 
    } else { 
      return super.getItemViewType(position); 
    } 
  } 
 
  @Override 
  public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View view; 
    if(viewType == PROGRESS_VIEW){ 
      view = LayoutInflater.from(parent.getContext()).inflate(R.layout.progressbar_item, parent, false); 
      return new ProgressViewHolder(view); 
    } else if(viewType == EMPTY_VIEW){ 
      return null; 
    } else if(viewType == IMAGE_VIEW){ 
      view = LayoutInflater.from(parent.getContext()).inflate(R.layout.image_news_item, parent, false); 
      return new ImageViewHolder(view); 
    } else { 
      view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_item, parent, false); 
      return new NewsViewHolder(view); 
    } 
  } 
 
  @Override 
  public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) { 
    holder.itemView.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
        clickListener.onItemClick(v, position); 
      } 
    }); 
    if(holder instanceof NewsViewHolder){ 
      NewsViewHolder viewHolder = (NewsViewHolder)holder; 
      viewHolder.title.setText(list.get(position).getTitle()); 
      viewHolder.time.setText(list.get(position).getTime()); 
      /** 
       * Glide加載圖片 
       */ 
      Glide.with(context).load(list.get(position).getImageUrl().get(0)) 
          .override(dpToPx(72), dpToPx(72)).centerCrop().into(viewHolder.image); 
      if(list.get(position).getType().equals(News.TEXT_NEWS)){ 
        viewHolder.digest.setText(list.get(position).getDigest()); 
      } else { 
        viewHolder.digest.setText(""); 
      } 
    } else if(holder instanceof ImageViewHolder){ 
      ImageViewHolder viewHolder = (ImageViewHolder)holder; 
      viewHolder.title.setText(list.get(position).getTitle()); 
      viewHolder.time.setText(list.get(position).getTime()); 
      setItemImage(viewHolder, list, position); 
    } else if(holder instanceof ProgressViewHolder){ 
      ProgressViewHolder viewHolder = (ProgressViewHolder)holder; 
      viewHolder.progressBar.setIndeterminate(true); 
 
    } 
  } 
 
  public void setItemImage(ImageViewHolder viewHolder, List<News> list, int position){ 
    viewHolder.imageMiddle.setVisibility(View.VISIBLE); 
    viewHolder.imageRight.setVisibility(View.VISIBLE); 
    DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics(); 
    if(list.get(position).getImageUrl().size() == 1){ 
      Glide.with(context).load(list.get(position).getImageUrl().get(0)) 
          .override(displayMetrics.widthPixels - dpToPx(10), dpToPx(90)) 
          .centerCrop().into(viewHolder.imageLeft); 
      viewHolder.imageMiddle.setVisibility(View.GONE); 
      viewHolder.imageRight.setVisibility(View.GONE); 
    } else if(list.get(position).getImageUrl().size() == 2){ 
      int imageWidth = (displayMetrics.widthPixels - dpToPx(20)) / 2; 
      Glide.with(context).load(list.get(position).getImageUrl().get(0)) 
          .override(imageWidth, dpToPx(90)) 
          .centerCrop().into(viewHolder.imageLeft); 
      Glide.with(context).load(list.get(position).getImageUrl().get(1)) 
          .override(imageWidth, dpToPx(90)) 
          .centerCrop().into(viewHolder.imageMiddle); 
      viewHolder.imageRight.setVisibility(View.GONE); 
    } else if(list.get(position).getImageUrl().size() >= 3){ 
      int imageWidth = (displayMetrics.widthPixels - dpToPx(30)) / 3; 
      Glide.with(context).load(list.get(position).getImageUrl().get(0)) 
          .override(imageWidth, dpToPx(90)) 
          .centerCrop().into(viewHolder.imageLeft); 
      Glide.with(context).load(list.get(position).getImageUrl().get(1)) 
          .override(imageWidth, dpToPx(90)) 
          .centerCrop().into(viewHolder.imageMiddle); 
      Glide.with(context).load(list.get(position).getImageUrl().get(2)) 
          .override(imageWidth, dpToPx(90)) 
          .centerCrop().into(viewHolder.imageRight); 
    } 
  } 
 
  @Override 
  public int getItemCount() { 
    return list.size(); 
  } 
 
  public int dpToPx(float dp){ 
    float px = context.getResources().getDisplayMetrics().density; 
    return (int)(dp * px + 0.5f); 
  } 
 
  class NewsViewHolder extends RecyclerView.ViewHolder{ 
    @BindView(R.id.news_title)TextView title; 
    @BindView(R.id.news_digest)TextView digest; 
    @BindView(R.id.news_time)TextView time; 
    @BindView(R.id.news_src)ImageView image;  
    public NewsViewHolder(View itemView) { 
      super(itemView); 
      ButterKnife.bind(this, itemView); 
    } 
  } 
 
  class ImageViewHolder extends RecyclerView.ViewHolder{ 
     @BindView(R.id.news_title) TextView title; 
    @BindView(R.id.image_left) ImageView imageLeft; 
    @BindView(R.id.image_right) ImageView imageRight; 
    @BindView(R.id.image_middle) ImageView imageMiddle; 
    @BindView(R.id.news_time) TextView time;  
    public ImageViewHolder(View itemView) { 
      super(itemView); 
      ButterKnife.bind(this, itemView); 
    } 
  } 
     
  class ProgressViewHolder extends RecyclerView.ViewHolder { 
    @BindView(R.id.progressBar) ProgressBar progressBar; 
    @BindView(R.id.textView) TextView textView;  
    public ProgressViewHolder(View itemView) { 
      super(itemView); 
      ButterKnife.bind(this, itemView); 
    } 
  } 
}

項(xiàng)目地址：https://github.com/xiyouZmt/E-Read

最后說(shuō)一下為什么為什么用RecyclerView取代ListView。

用過(guò)ListView的都知道，在ListView中若要復(fù)用視圖緩存，就要在getView()方法中手動(dòng)判斷convertView是否為空，若不為空則復(fù)用視圖緩存，若為空則重新加載視圖，而RecyclerView相當(dāng)于對(duì)ListView的Adapter進(jìn)行了再次封裝，把ListView手動(dòng)判斷是否有緩存的代碼封裝到RecyclerView內(nèi)部，使這部分邏輯不可見(jiàn)，我們只需要通過(guò)getItemCount()方法告訴RecyclerView有多少項(xiàng)數(shù)據(jù)，然后在onCreateViewHolder()中加載item布局實(shí)例化ViewHolder，然后在onBindViewHolder()中完成數(shù)據(jù)的綁定即可。

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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