聊天界面demo

简易demo：
activity_main:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#d8e0e8"
    android:orientation="vertical"
    tools:context="com.example.chatdemo.MainActivity">

    <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:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:id="@+id/input_text"
            android:maxLines="2"
            android:hint="请输入信息"/>
        <Button
            android:id="@+id/sent"
            android:text="发送"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    LinearLayout>
LinearLayout>

msg_item:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dp"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/left_layout"
        android:layout_gravity="left"
        android:background="@drawable/message_left">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/left_msg"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:textColor="#fff"/>
    LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/right_layout"
        android:layout_gravity="right"
        android:background="@drawable/message_right">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/right_msg"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:textColor="#fff"/>
    LinearLayout>
LinearLayout>

Msg:

public class Msg {
    public static final int TYPE_RECEIVED = 0;
    public static final int TYPE_SENT = 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;
    }
}

MsgAdapter:

public class MsgAdapter extends ArrayAdapter {
    private int resourceId;

    public MsgAdapter(Context context,int textViewResourceId,List 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.leftMsg = (TextView)view.findViewById(R.id.left_msg);
            viewHolder.rightLayout = (LinearLayout)view.findViewById(R.id.right_layout);
            viewHolder.rightMsh = (TextView)view.findViewById(R.id.right_msg);
            view.setTag(viewHolder);
        }
        else {
            view = convertView;
            viewHolder = (ViewHolder)view.getTag();
        }
        if(msg.getType() == Msg.TYPE_RECEIVED){
            viewHolder.leftLayout.setVisibility(View.VISIBLE);
            viewHolder.rightLayout.setVisibility(View.GONE);
            viewHolder.leftMsg.setText(msg.getContent());
        }
        else {
            viewHolder.rightLayout.setVisibility(View.VISIBLE);
            viewHolder.leftLayout.setVisibility(View.GONE);
            viewHolder.rightMsh.setText(msg.getContent());
        }
        return view;
    }

    class ViewHolder {
        LinearLayout leftLayout;
        LinearLayout rightLayout;
        TextView leftMsg;
        TextView rightMsh;
    }
}

MainActivity:

public class MainActivity extends AppCompatActivity {
    private ListView msgListView;
    private EditText inputText;
    private Button send;
    private MsgAdapter adapter;
    private List msgList = new ArrayList();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        initMsg();

        adapter = new MsgAdapter(MainActivity.this,R.layout.msg_item,msgList);

        inputText = (EditText)findViewById(R.id.input_text);
        send = (Button)findViewById(R.id.sent);
        msgListView = (ListView)findViewById(R.id.msg_list_view);
        msgListView.setAdapter(adapter);
        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String content = inputText.getText().toString();
                if(!"".equals(content)){
                    Msg msg = new Msg(content,Msg.TYPE_SENT);
                    msgList.add(msg);
                    adapter.notifyDataSetChanged();
                    msgListView.setSelection(msgList.size());
                    inputText.setText("");
                }
            }
        });
    }

    public  void initMsg(){
        Msg msg1 = new Msg("11111111111",Msg.TYPE_RECEIVED);
        msgList.add(msg1);
        Msg msg2 = new Msg("2222222222",Msg.TYPE_SENT);
        msgList.add(msg2);
    }
}