以下是工程目录结构：
接下来就是如何实现这个效果的代码：
main.xml，这个是主布局文件，显示listview和上下两部分内容。
代码如下:
然后就是listview中两种类型item的布局文件，分别是接收信息的item效果和发送信息的item效果
chat_from_item.xml是接收信息的item布局：
代码如下:
chat_to_item.xml是发送信息item的布局：
代码如下:
布局完成后新建一个实体类ChatEntity.java：
代码如下:
public class ChatEntity {
private int userImage;
private String content;
private String chatTime;
private boolean isComeMsg;
public int getUserImage() {
return userImage;
}
public void setUserImage(int userImage) {
this.userImage = userImage;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getChatTime() {
return chatTime;
}
public void setChatTime(String chatTime) {
this.chatTime = chatTime;
}
public boolean isComeMsg() {
return isComeMsg;
}
public void setComeMsg(boolean isComeMsg) {
this.isComeMsg = isComeMsg;
}
}
最后就是主Activity，这里面包括了自己写的BaseAdapter：
代码如下:
public class ChatDemoActivity extends Activity {
private Button sendButton = null;
private EditText contentEditText = null;
private ListView chatListView = null;
private List chatList = null;
private ChatAdapter chatAdapter = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
contentEditText = (EditText) this.findViewById(R.id.et_content);
sendButton = (Button) this.findViewById(R.id.btn_send);
chatListView = (ListView) this.findViewById(R.id.listview);
chatList = new ArrayList();
ChatEntity chatEntity = null;
for (int i = 0; i < 2; i++) {
chatEntity = new ChatEntity();
if (i % 2 == 0) {
chatEntity.setComeMsg(false);
chatEntity.setContent("Hello");
chatEntity.setChatTime("2012-09-20 15:12:32");
}else {
chatEntity.setComeMsg(true);
chatEntity.setContent("Hello,nice to meet you!");
chatEntity.setChatTime("2012-09-20 15:13:32");
}
chatList.add(chatEntity);
}
chatAdapter = new ChatAdapter(this,chatList);
chatListView.setAdapter(chatAdapter);
sendButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (!contentEditText.getText().toString().equals("")) {
//发送消息
send();
}else {
Toast.makeText(ChatDemoActivity.this, "Content is empty", Toast.LENGTH_SHORT).show();
}
}
});
}
private void send(){
ChatEntity chatEntity = new ChatEntity();
chatEntity.setChatTime("2012-09-20 15:16:34");
chatEntity.setContent(contentEditText.getText().toString());
chatEntity.setComeMsg(false);
chatList.add(chatEntity);
chatAdapter.notifyDataSetChanged();
chatListView.setSelection(chatList.size() - 1);
contentEditText.setText("");
}
private class ChatAdapter extends BaseAdapter{
private Context context = null;
private List chatList = null;
private LayoutInflater inflater = null;
private int COME_MSG = 0;
private int TO_MSG = 1;
public ChatAdapter(Context context,List chatList){
this.context = context;
this.chatList = chatList;
inflater = LayoutInflater.from(this.context);
}
@Override
public int getCount() {
return chatList.size();
}
@Override
public Object getItem(int position) {
return chatList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public int getItemViewType(int position) {
// 区别两种view的类型，标注两个不同的变量来分别表示各自的类型
ChatEntity entity = chatList.get(position);
if (entity.isComeMsg())
{
return COME_MSG;
}else{
return TO_MSG;
}
}
@Override
public int getViewTypeCount() {
// 这个方法默认返回1，如果希望listview的item都是一样的就返回1，我们这里有两种风格，返回2
return 2;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ChatHolder chatHolder = null;
if (convertView == null) {
chatHolder = new ChatHolder();
if (chatList.get(position).isComeMsg()) {
convertView = inflater.inflate(R.layout.chat_from_item, null);
}else {
convertView = inflater.inflate(R.layout.chat_to_item, null);
}
chatHolder.timeTextView = (TextView) convertView.findViewById(R.id.tv_time);
chatHolder.contentTextView = (TextView) convertView.findViewById(R.id.tv_content);
chatHolder.userImageView = (ImageView) convertView.findViewById(R.id.iv_user_image);
convertView.setTag(chatHolder);
}else {
chatHolder = (ChatHolder)convertView.getTag();
}
chatHolder.timeTextView.setText(chatList.get(position).getChatTime());
chatHolder.contentTextView.setText(chatList.get(position).getContent());
chatHolder.userImageView.setImageResource(chatList.get(position).getUserImage());
return convertView;
}
private class ChatHolder{
private TextView timeTextView;
private ImageView userImageView;
private TextView contentTextView;
}
}
}
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