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);
}
}
