编写精美聊天界面，那就肯定要有收到的消息和发送的消息。

首先还是编写主界面，修改activity_chat.xml中的代码，如下所示：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="#d8e0e8"

android:orientation="vertical" >

 

<ListView

android:id="@+id/msg_list_view"

android:layout_width="match_parent"

android:layout_height="0dp"

android:layout_weight="1"

android:divider="#0000" />

 

 

<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

>

 

<EditText

android:id="@+id/input_text"

android:layout_width="0dp"

android:layout_height="wrap_content"

android:layout_weight="1"

android:hint="Type something here"

android:maxLines="2"

/>

 

<Button

android:id="@+id/send"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="send"

/>

 

</LinearLayout>

 

</LinearLayout>

这里在主界面中放置一个ListView用于显示聊天的消息内容，又放置一个EditText用于输入聊天消息，还放置了一个Button用于发送消息。ListView中用到了一个adnroid:divider属性，它可以指定ListView分割线的颜色，这里#0000表示将分割线设为透明色。

然后定义消息的实体类，新建Msg，代码如下所示：

public class Msg {

 

public static final int TYPE_RECEIVER = 0;

public static final int TYPE_SEND = 1;

 

private String content;

private int type;

 

public Msg(String content, int type) {

this.content = content;

this.type = type;

}

 

 

public String getContent() {

return content;

}

 

public int getType() {

return type;

}

 

}

Msg类中只有两个字段，content表示内容，type表示消息的类型。

编写ListView子项的布局

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:padding="10dp">

 

<LinearLayout

android:id="@+id/left_layout"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="left"

android:background="@drawable/ease_chatfrom_bg_focused"

android:visibility="gone"

>

 

<TextView

android:id="@+id/left_msg"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:layout_margin="10dp"

android:textColor="#000"

/>

 

</LinearLayout>

 

<LinearLayout

android:id="@+id/right_layout"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="right"

android:background="@drawable/ease_chatto_bg_focused"

android:visibility="gone"

>

<TextView

android:id="@+id/right_msg"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:layout_margin="10dp"

android:textColor="#fff"

/>

 

 

</LinearLayout>

 

 

</LinearLayout>

编写ListView的适配器

public class MsgAdapter extends ArrayAdapter<Msg>{

 

private int resourceId;

 

public MsgAdapter(Context context, int textViewResourceId, List<Msg> objects) {

super(context, textViewResourceId, objects);

resourceId = textViewResourceId;

}

 

@Override

public View getView(int position, View convertView, ViewGroup parent) {

Msg msg = getItem(position);

View view;

ViewHolder viewHolder;

if(convertView == null){

view = LayoutInflater.from(getContext()).inflate(resourceId, null);

viewHolder = new ViewHolder();

viewHolder.leftLayout = (LinearLayout) view.findViewById(R.id.left_layout);

viewHolder.rightLayout = (LinearLayout) view.findViewById(R.id.right_layout);

viewHolder.leftMsg = (TextView) view.findViewById(R.id.left_msg);

viewHolder.rightMsg = (TextView) view.findViewById(R.id.right_msg);

 

view.setTag(viewHolder);

}else {

view = convertView;

viewHolder = (ViewHolder) view.getTag();

}

 

if(msg.getType() == Msg.TYPE_RECEIVER){

//接收消息 左边的消息

viewHolder.rightLayout.setVisibility(View.GONE);

viewHolder.leftLayout.setVisibility(View.VISIBLE);

viewHolder.leftMsg.setText(msg.getContent());

}else if(msg.getType() == Msg.TYPE_SEND){

//发送消息 右边的消息

viewHolder.leftLayout.setVisibility(View.GONE);

viewHolder.rightLayout.setVisibility(View.VISIBLE);

viewHolder.rightMsg.setText(msg.getContent());

}

 

return view;

}

 

class ViewHolder{

LinearLayout leftLayout;

LinearLayout rightLayout;

TextView leftMsg;

TextView rightMsg;

 

}

 

}

编写ChatActivity

public class ChatActivity extends Activity{

private MsgAdapter msgAdapter ;

private EditText inputText ;

private Button send ;

private ListView mListView ;

ArrayList<Msg> msgList = new ArrayList<Msg>();

 

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

requestWindowFeature(Window.FEATURE_NO_TITLE);

setContentView(R.layout.activity_chat);

initMsgs();

msgAdapter = new MsgAdapter(ChatActivity.this, R.layout.chat_list_item, msgList);

inputText = (EditText) findViewById(R.id.input_text);

send = (Button) findViewById(R.id.send);

mListView = (ListView) findViewById(R.id.msg_list_view);

mListView.setAdapter(msgAdapter);

send.setOnClickListener(new OnClickListener() {

 

@Override

public void onClick(View v) {

String content = inputText.getText().toString();

if(!"".equals(content)){

Msg msg = new Msg(content, Msg.TYPE_SEND);

msgList.add(msg);

msgAdapter.notifyDataSetChanged();//当有消息时刷新listview列表显示

mListView.setSelection(msgList.size());//将listview定位在最后一行

inputText.setText("");//输入框内容清空

}

 

}

});

}

 

private void initMsgs() {

Msg msg1 = new Msg("hello", Msg.TYPE_RECEIVER);

msgList.add(msg1);

 

Msg msg2 = new Msg("hello who is what", Msg.TYPE_SEND);

msgList.add(msg2);

 

Msg msg3 = new Msg("your friend", Msg.TYPE_RECEIVER);

msgList.add(msg3);

 

}

 

}