编写精美的聊天界面

一、运行效果图

二、核心代码

Mainactivity

public class MainActivity extends Activity {
	
	private ListView msgListView;

	private EditText inputText;

	private Button send;
	
	private MsgAdapter adapter;

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

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		initMsgs(); // 初始化消息数据
		adapter = new MsgAdapter(MainActivity.this, R.layout.msg_item, msgList);
		inputText = (EditText) findViewById(R.id.input_text);
		send = (Button) findViewById(R.id.send);
		msgListView = (ListView) findViewById(R.id.msg_list_view);
		msgListView.setAdapter(adapter);
		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_SENT);
					msgList.add(msg);
					adapter.notifyDataSetChanged(); // 当有新消息时，刷新ListView中的显示
					msgListView.setSelection(msgList.size()); // 将ListView定位到最后一行
					inputText.setText(""); // 清空输入框中的内容
				}
			}
		});
	}

	private void initMsgs() {
		Msg msg1 = new Msg("Hello guy.", Msg.TYPE_RECEIVED);
		msgList.add(msg1);
		Msg msg2 = new Msg("Hello. Who is that?", Msg.TYPE_SENT);
		msgList.add(msg2);
		Msg msg3 = new Msg("This is Tom. Nice talking to you. ", Msg.TYPE_RECEIVED);
		msgList.add(msg3);
	}

}

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_RECEIVED) {
			// 如果是收到的消息，则显示左边的消息布局，将右边的消息布局隐藏
			viewHolder.leftLayout.setVisibility(View.VISIBLE);
			viewHolder.rightLayout.setVisibility(View.GONE);
			viewHolder.leftMsg.setText(msg.getContent());
		} else if(msg.getType() == Msg.TYPE_SENT) {
			// 如果是发出的消息，则显示右边的消息布局，将左边的消息布局隐藏
			viewHolder.rightLayout.setVisibility(View.VISIBLE);
			viewHolder.leftLayout.setVisibility(View.GONE);
			viewHolder.rightMsg.setText(msg.getContent());
		}
		return view;
	}

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

}

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;
	}

}

三、遇到的问题

制作聊天框时刚开始不会操作，后来研究了一下。从网上找的图片制作成功。

新建MsgAdapter这个类时要引入import android.view.View;