ListView实现聊天列表之处理不同数据项

作者：袖梨 2022-06-25
通常我们用惯的ListView每一项的布局都是相同的，只是控件所绑定的数据不同。但单单只是如此并不能满足我们某些特殊需求，比如我们常见的QQ、微信的聊天列表，除了有左右之分外，内容更是有很大区别，有文字、语音、图片、视频等等，他们真的是ListView可以实现的吗？答案是肯定的，只要我们做一下类型区别即可。

实现效果如下所示：

    大家不要在意布局，这里为了方便就随意了。大家可以看到，这里有两种布局，一种头像在左，一种头像在右，虽然这是一种简单的情况，但我们只需要了解其中的原理，再复杂的情况都可以迎刃而解。
我们只要将每一种布局划为一种类型进行区分，根据我们所区分的类型在我们自定义的Adapter中加载不同布局即可，代码如下所示： 

if (bean.getType() == 1) { 
      convertView = mInflater.inflate(R.layout.item_chat_left, null); 
      holder.mIvAvatar = (ImageView) convertView.findViewById(R.id.iv_chatLeftItem_avatar); 
      holder.mTvContent = (TextView) convertView.findViewById(R.id.tv_chatLeftItem_content); 
  } else if (bean.getType() == 2) { 
      convertView = mInflater.inflate(R.layout.item_chat_right, null); 
      holder.mIvAvatar = (ImageView) convertView.findViewById(R.id.iv_chatRightItem_avatar); 
      holder.mTvContent = (TextView) convertView.findViewById(R.id.tv_chatRightItem_content); 
  }

是不是发现很简单，最后，我再将所有代码一同贴出来。

item_chat_left.xml

item_chat_right.xml

activity_chat.xml

ChatItemBean.java 

import android.graphics.Bitmap; 
 
public class ChatItemBean { 
  private int type; 
  private String content; 
  private Bitmap avatar; 
  public int getType() { 
    return type; 
  } 
  public void setType(int type) { 
    this.type = type; 
  } 
  public String getContent() { 
    return content; 
  } 
  public void setContent(String content) { 
    this.content = content; 
  } 
  public Bitmap getAvatar() { 
    return avatar; 
  } 
  public void setAvatar(Bitmap avatar) { 
    this.avatar = avatar; 
  } 
}

ChatLVAdapter.java 

import java.util.List; 
 
import android.content.Context; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 
import android.widget.TextView; 
 
public class ChatLVAdapter extends BaseAdapter { 
 
  private List mDatas; 
  private LayoutInflater mInflater; 
   
  public ChatLVAdapter(Context context, List datas) { 
    this.mInflater = LayoutInflater.from(context); 
    this.mDatas = datas; 
  } 
   
  @Override 
  public int getCount() { 
    return mDatas.size(); 
  } 
 
  @Override 
  public Object getItem(int position) { 
    return mDatas.get(position); 
  } 
 
  @Override 
  public long getItemId(int position) { 
    return position; 
  } 
 
  @Override 
  public View getView(int position, View convertView, ViewGroup parent) { 
    ViewHolder holder = null; 
    ChatItemBean bean = mDatas.get(position); 
    if (convertView == null) { 
      holder = new ViewHolder(); 
      if (bean.getType() == 1) { 
        convertView = mInflater.inflate(R.layout.item_chat_left, null); 
        holder.mIvAvatar = (ImageView) convertView.findViewById(R.id.iv_chatLeftItem_avatar); 
        holder.mTvContent = (TextView) convertView.findViewById(R.id.tv_chatLeftItem_content); 
      } else if (bean.getType() == 2) { 
        convertView = mInflater.inflate(R.layout.item_chat_right, null); 
        holder.mIvAvatar = (ImageView) convertView.findViewById(R.id.iv_chatRightItem_avatar); 
        holder.mTvContent = (TextView) convertView.findViewById(R.id.tv_chatRightItem_content); 
      } 
      convertView.setTag(holder); 
    } else { // 通过tag找到缓存的布局 
      holder = (ViewHolder) convertView.getTag(); 
    } 
    holder.mIvAvatar.setImageBitmap(bean.getAvatar()); 
    holder.mTvContent.setText(bean.getContent()); 
     
    return convertView; 
  } 
   
  public final class ViewHolder { 
    public ImageView mIvAvatar; 
    public TextView mTvContent; 
  }

ChatActivity.java 

import java.util.ArrayList; 
import java.util.List; 
 
import android.app.Activity; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.widget.ListView; 
 
public class ChatActivity extends Activity { 
  private ListView mLv; 
  private List mDatas ; 
  private ChatLVAdapter mAdapter; 
   
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_chat); 
     
    mLv = (ListView) findViewById(R.id.lv_content); 
 
    initData(); 
    mAdapter = new ChatLVAdapter(this, mDatas); 
    mLv.setAdapter(mAdapter); 
  } 
 
  private void initData() { 
    mDatas = new ArrayList(); 
    ChatItemBean chat1 = new ChatItemBean(); 
    chat1.setType(1); 
    chat1.setContent("早啊！"); 
    chat1.setAvatar(BitmapFactory.decodeResource(getResources(), R.drawable.ic_item1)); 
    mDatas.add(chat1); 
    ChatItemBean chat2 = new ChatItemBean(); 
    chat2.setType(2); 
    chat2.setContent("早！一大早找我有啥事？"); 
    chat2.setAvatar(BitmapFactory.decodeResource(getResources(), R.drawable.ic_item2)); 
    mDatas.add(chat2); 
    ChatItemBean chat3 = new ChatItemBean(); 
    chat3.setType(1); 
    chat3.setContent("没事就不能找你谈情说爱吗？也没什么事，看你有没有在撸代码。"); 
    chat3.setAvatar(BitmapFactory.decodeResource(getResources(), R.drawable.ic_item1)); 
    mDatas.add(chat3); 
    ChatItemBean chat4 = new ChatItemBean(); 
    chat4.setType(2); 
    chat4.setContent("算了吧，别找我！我害怕。"); 
    chat4.setAvatar(BitmapFactory.decodeResource(getResources(), R.drawable.ic_item2)); 
    mDatas.add(chat4); 
    ChatItemBean chat5 = new ChatItemBean(); 
    chat5.setType(2); 
    chat5.setContent("都被代码撸惨了，我哪敢一早起来找虐。"); 
    chat5.setAvatar(BitmapFactory.decodeResource(getResources(), R.drawable.ic_item2)); 
    mDatas.add(chat5); 
  } 
}

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